32
\ \ \ \ \ ‘\ ‘ \\ ct
MAPLIN HOME BURGLAR ALARM PROJECTS MODEL TRAIN CONTROLLER
MULTI-MODE STOPWATCH
14-CHANNEL 2-WIRE
BOOK TWe MILES-PER-GALLON METER 0
‘14 0 s6
S7 001
001
6 e•-• roes
FN RA C c•A
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eat An14 THE M APLI N M AGAZI NE
This project book completely replaces issue 2 of 'Electronics', which is now out of print. Other issues of 'Electronics' will be replaced by project books as they, too, become out of print.
For kit prices, please consult the latest Maplin price list. The price list also contain details of how to obtain a year's subscription to 'Electronics'.
CONTENTS Projects Page Burglar Alarm 3 A home security system offering reliable, long-term protection.
Miles-Per-Gallon Meter 27 Save petrol when you learn to drive economically with the aid of this invaluable meter.
Stopwatch 13 Multi-mode stopwatch with 8-digit readout.
Train Controller 16 Control up to 14 locomotives on one 2-wire circuit — up to four simultaneously.
Editor Doug Simmons Production Manager Sue Clark Technical Editors Robert Kirsch
Dave Goodman
Art Editor Technical Artists
Photography
Peter Blackmore Roy Smith John Dudley Chris Barlow
Published by Maplin Electronic Supplies Ltd, PO Box 3, Rayleigh, Essex
Printed by Mayhew McCrimmon Ltd. Typeset by Quil'set Typesetting
For Personal Service
CALL IN AT ONE OF OUR SHOPS
We have shops in London, Birmingham and Southend
LONDON 159-161 King Street, Hammersmith W6.
Telephone: 01-748 0926.
BIRMINGHAM Lynton Square, Perry Barr (junction of A34 and A4040). Telephone: 021-356 7292.
SOUTHEND 282-284 London Road, Westcliff-on-Sea, Essex.
Telephone: (0702) 554000.
Excellent parking at all locations. All shops open 9 a.m. to 5.30 p.m. Tuesday to Saturday (closed Monday).
Copyright All material is subject to world-wit* Cippyri alprotechein, and reproduction Or imitation in whoteor part is expressly forbidden, All reasonable care is taken to ensure accuracy in p eparation of the magazine but Maplin Publications cannot be held legally responsible for its contents, Where errors occur corrections will be published as soon as possible afterwards. Permission to reproduce printed circuit board layouts commercially or marketing of kits must be sought from the Publisher. ccopyright 1982 Maplin Publications.
HOME SECURITY SYSTEM by Dave Goodman
* Six independent channels with two groups per channel
* Two or four wire operation with line sensing of open or short circuit or resistance change (jumping)
* Tamper-proof main cabinet * External horn loop control has its own open/short circuit and jumping protection
* Presettable entry and exit delay timers
This new home security system offers a high degree of protection for domestic or commercial pre-
mises coupled with excellent long-term reliability. The unit is mains operated, but will run off its small internal nickel-cadmium rechargeable battery pack for 2 to 3 days depending on the size of the system. The internal battery is continuously charged when the mains is present and changeover from mains to battery and vice-versa has no effect on the system. CMOS circuitry is used throughout to minimise current drain. There are sockets for six separate
plug-in channels so that for example all downstairs windows could be connec-ted to one input, all downstairs doors to another, all upstairs windows to another and perhaps shed and garage doors and windows to another. When setting the system you know immediately where to look for the window left open accidentally if the system will not set. Or parts of the system only may be set. For example, during the late evenings, the shed and garage circuit only could be set. Whatever your requirements this system offers the fullest possible flexi-bility for complete security. The external horn is also fully pro-
tected when fitted with dry batteries. Its prominent position alone will deter most burglars, but any attempt to tamper with it will set it off. If the wires to it are cut or tampered with, the horn will sound. Even ripping the box off the wall will not stop the alarm. The recom-mended dry batteries will sound the alarm at full power for at least four hours even if the wires are cut. The alarm is extremely easy to build,
with internal wiring kept to an absolute minimum. Operation is by a single keyswitch and exit and entry delays
Minimum system cost UNDER £50!
may be preset to suit your require-ments. There is an LED for each chan-nel, giving monitoring facilities and an internal sounder giving 'alarm condi-tion' tones. Even the main cabinet is protected, by a microswitch fitted to the PSU pcb.
Circuit Description Mains PCB
The key switch S9, which is shown in Figure 1 with its contacts made, con-trols the 'disarm' and 'set' conditions of the alarm unit. TRI is conducting and thus inhibiting the exit delay timer oscillator IC1c and d, and IC2, a 14 stage counter/divider, is held reset. The oscillator IC1c and d is fre-
quency variable between 25Hz (40ms) and 10kHz (100us). This clock signal is divided down by IC2 by 8192 giving a minimum time out period of 0.8s and a maximum period of 5.5 mins. So allowing for variations in tolerances, IC1c, d and IC2 function as an exit delay timer presettable by RVI giving periods of between 0 and 6 mins. ICI a, b and IC3 function as des-
cribed above but are used as an entry delay timer, presettable by RV2. In the disarm mode IC2 pin 3 is at OV
and D2 is conducting. Consequently exit delay tone modulator IC5 c and d is inhibited. IC10a output is high, holding TR5 and LED9 ('ARM' LED) off. Latch
ICIO band d output is high. Entry delay timer is held off via D4 and IC10b output low. Counter IC3 pin 3 is low and alarm tone modulator IC5a and b is inhibited via D7 conducting. Latches IC7, 8 and 9 have normally
high outputs connected to LED buffer ICII preventing channel LEDs 3 to 8 from turning on. A positive trigger pulse greater than 25ms in duration present at any of the inputs to the latches from switches S3 to 8 allows the channel LEDs to turn on for the duration of the triggering signal. Switch S2 operates TR7 which dis-
charges C13 and operates TR6, the LED display. TR6 remains on for the time constant set by R43 and C13, approxi-mately 90s. Operating switch S9 (contacts Gpen)
in the 'set' mode turns TRI off. This removes the inhibit on the exit delay oscillator IC1c and d allowing it to run at the frequency determined by RVI. IC2 divides this signal and IC2 pin 3 goes high. While IC2 is counting, D2 is not conducting and IC5 c and d run at a frequency of approximately 8Hz. The inhibit on the tone generator IC6 band c is removed allowing it to run at approxi-mately 3kHz modulated at 8Hz. At the end of the timing period, IC2
pin 3 goes high, inhibiting IC5d and IC6d. IC10a goes low, TR5 conducts and the 'ARM' LED turns on. IC10d inhibit is removed and a positive trigger pulse from switches S3 to 8 latches
3
OV
-I 1 10k
TR2 BC548
24
0
+15V
18
C11
Chan 3
04
+5V
SKI
02
12 8 OV
• R4 1k ea
RV1 a 1M C3 MI
27nF Or
IC1a IC1b
IC4d 2 11
All 120k
OV
7 010
011
• Ki •
S3
a "s
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IC3
• 30
OM C7 100nF
29 OV 0
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OV -411- C h a n.1 012
Cs SK2 S4
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Chan.2
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a SK4 4 S6
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in I SK5 o. S7
0 0 '0 - 6 - 0-- i:2I cc 8 t_ 016 °V I
Chan .5
8 IC7c
IC8a
IC8c
10
3
10
IC4a 3
47k
03
OV
IC5c 8 10 13
9 R13
IC5d 12_.D . R15
1M
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2 11
13
07
3
68k DB
09
IC5a 3 5 4 6 IC5b R16
22k 2 R14
1M
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C9 820nF
1N4148
4001BE IC2.3:- 4020BE IC11:- 4050BE
R35
1k
TR4 BC548
IC7b IC1113 R36
o .
13 IC7d
12
5
11 IC11c
7 >6
IC8b IC11a
• 3 > 2
lk
R37
I } lk
R38
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LED3
N.:4k
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LED 4
LEDS
IC8d 1C M 14 >
13 R 39 Nklk-i— r- y;
12
• K) • IC 9b IC11e 10 S8 I IC9a 6 R40
SK6 1 4 11 > 12 3 1
0 0 0 - 0 -0 0 {cNc _ co io •
2 5 1k
Chan 6 I1 0V- 1-OV R30 017
1k LED 6
I • KJ V 100nF
D18 100k
R31 12 IC10d
1M 11 •
13
IC10b
4
3
10k
2 IC10 a
13 10 —_ DID1
12
IC9d
32 4- LED 9
R33
lk 31
OV
9 10
TR6 BC 548
R42 10k
IC11d R41
1k
IC 10c
+5V R43 1M2
Ext. Horn Alarm
1) 7 >, C12 8 1 + 9 • C13 019 BC548
m 7100nF • 47uF
sz
IC6c
R18 10k
9
R17
•-[ }-* R19
10k 470kH :
C10 IC6b NM 330pF
6
TR7
+5V
R20 Int. Horn
I-1 10k IPiezol
+15V 27
H1
TR3 BC 548
OV
23
LED 1
Power
21 +5V .4 - 0
20 +15V -44- -(3
19 OV
+5V to:-Pin1 IC11 Pin 14 ICs1.4-10 Pm16 ICs 2.3
OV Pin 7 ICs1.4 -10 Pin8 ICs 2.3,11
Display ON
25
R45 3k9
020
3k9
R44 1k2
IC10d low. The appropriate IC7, 8 or 9 goes low and latches, operating a channel LED. This same trigger pulse also re-
moves the inhibit on the entry delay oscillator ICla and b via ICIO band d. Consequently it begins to run at the frequency set by RV2. IC3 divides the clock signal and when pin 3 goes high the oscillator stops running, TR2 con-ducts, latching IC4 a and b, and operat-ing LED 2. Alarm tone modulator IC5a and b
runs at 0 to 5 Hz and modulates the 3kHz tone oscillator IC6b and c de-veloping the alarm tone signal at HI.
Power Supply The power supply is shown in Figure
2. Ti, BRI and C2 provide 15V to the LED arrays, speaker output stages and charging circuit. Cl is a 0.1uF inter-ference suppressor, which removes transient spikes from the mains. LEDI, R3, RI, TRI and D1 form a
constant current source for charging the six 1.2V nickel cadmium batteries used for power failure standby. The alarm current requirement is very low so that fully charged batteries will pro-vide enough power for a few days. The trickle charge is set by RI to 4mA and is temperature stabilised by LEDI. The supply voltage at pin 7 is
approximately 15V and the battery supply is 7.5V. 02 will normally be reversed biased when mains voltage is applied and REGI will deliver +5V at 100mA. LEDI also serves as a mains pilot light. Removing the mains supply ex-
tinguishes LED1, removes the charging current and forward biases 02. Pin 7 drops to +7.5V while pin 8 remains at +5V. C3 flizi 4 ensure that no spurious spikes are produced during change-over to battery standby. The batteries should be checked periodically. If standby power is not required, short circuit pins 4 and 5 together to light LEDI.
Break Contact Module The break contact module shown in
Figure 3 works on a balanced line system. The line (contact) inputs, 1 and 2, are set for +2.5V measured on TPA and TPB and adjusted with RV1 and RV2. Up to five switch contacts (and 22k
resistors) are used on each input allowing ten contacts per module as shown on Figure 18. The number used is dependant on the system mode chosen. ICI has R3 connected between
input and inverting output. The gate is therefore used in its linear region and the output (at the test points) will be balanced at half the supply. A high or low voltage swing, at the
inputs, is detected by ICla and d, and the output, normally low, will pulse high for the duration of the input change.
External Horn The external horn circuit is shown
in Figure 4. RI terminates the security
FS1
100-A
Cl 100,,F
ff,t
3
61/
OV
6V
OA
LED 1 1
100 QB
C2 0
2200 i i.0
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RI 2201
III
BC2I4L
DI
03 •15V
70
02
01-3:• 1N4001
13
REG 1
12 10k
SI
11
0.1
GOR10100
•
C4
100nF
tto
6o RECT. uA7BLOSAWC OV
Figure 2. Circuit diagram of PSU.
I/P1 911
+5V
I/P2
RV1 22k
R1 2k2
R2 8 t 2k2
RV2 22k
R6 2k2
Al
2 k 2
R3
100k IC 1c
R8
100k
IC1b
10 TPA
C1 100nF
ov
C2 D1-4:- 1N4148 100nF ,c,:. 4011BE
01 R4
TPB
02
D3
04
100k
R9
100k
1 R5 180k
12
13
'Cl PIN 14
IC1d
+5V
11 0/P
IC1a
IC1 R10 PIN 7 180k
Figure 3. Circuit diagram of Break Contact Module.
Figure 4. Circuit diagram of External Horn PCB.
loop connected from pins 1 and 2 to pins 30 and 29 on the main PCB. A current, set at 3mA, is generated in the loop and cutting, short circuiting or reversing, will bias TRI into conduc-tion. TR2 will switch on and the battery pack then supplies H2. Returning the loop back to its
normal condition would appear to bias TRI off and prevent H2 from operat-ing. This does not happen, owing to detection circuit IC4c, d (Figure 1)
R10, 11, 12 and D6 switching, and dropping the loop current down to 1 mA. The horn will continue to sound until the main alarm key switch is turned off. Please note that with internal bat-
teries connected, the horn will sound immediately, until the security loop is connected. So when fitting the system, the loop must be wired to the main alarm first, and then connect the batteries (see Figure 9).
5
,000,000 009 009- 1 000 009 u. 2 0 4 5 6 7 8 10 11 1 13 14 15 16 17 10
1\ 1\ \
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11\ /11 1116.
BURGLAR ALARM MAIN BOARD GA45Y
29
0
Cl
TR1
5 e 1 6_
I' Minutes RV1 IC2
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RV2
N cc
EXIT DEL AY
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Pic. A Internal view of control box with Main PCB fitted to the door and the PSU mounted in the base of the box.
Construction Assembly and Setting Up Main PCB Refer to the parts list 1 and Figure
10. Use 24 swg BTC (or E/C) wire to make the 28 link straps and fit these first. Next, fit the Veropins and the diodes. (The black tips are shown as white blocks on the legend.) Fit all resis-tors and capacitors. Note that electroly-tic and tantalum types are polarised and have a '+' sign which must be correctly orientated. Fit transistors and IC sockets. Fit the two cermet presets RV1 and 2, and turn fully clockwise, to 0 on the legend. Connect a lkO test resistor RT across pins 29 and 30. (Note - this will be removed when using the exter-nal horn PCB, but must remain in place
if the external PCB is not in use.) Refer to Figures 11 and 13 when
mounting the channel LEDs. LEDs 1 to 8 are mounted to the PCB from the track side. Figure 13 shows the lead designa-tions. Place the correctly orientated LED into position and insert a spacing strip 8mm x 1.5mm (spare Veroboard etc) between the legs. Bend the legs under the PCB, to hold in position and solder one leg only. Repeat for all eight LEDs. Figure 12 shows the mounting
procedure for fitting the PCB to the inside cabinet lid. Place five 1" x 6BA CSK screws through the lid, tighten down with five 6BA nuts and washers. Place five 6BA x 1/4" spacers over the
screws and offer the PCB to the lid, positioning the channel LEDs in the holes provided. With LEDs correctly positioned, remove the PCB and solder the eight remaining LED legs. Re-check all component values and positionings. Check for dry joints, solder splashes and short circuits on the track face. If all is in order, mount the PCB on to the lid and hold with five 6BA washers and nuts. Push switch S2 mounts through the
PCB and lid and is wired to adjacent pins 25 and 26. Mount LED 9 and con-nect to pins 31 and 32 (Figure 10). Mount key switch S9 and piezo horn HI using two 1/4" x 6BA CSK nuts, bolts, washers. Wire HI to pins 27 and 28.
BURGLAR ALARM PSU
MAPLIN
FS1
41:
0.1 0
C3
Ti
D3 TH1 += I—
REG 1 R 2r...\ R1 R3 13
r-+ +15vC4 -1 - = 1 0 V 0 0 0
O b 7 +5V 8 9 10 11
•
Figure 6a. Component overlay of PSU PCB.
7
I— BREAK CONTACT BO (38 TOATI1O'J AA 328
S 281 RV2
I L
RV 1
2 —C:=D•4 L
D4 -4- 1— = 3- R10 ;;
1,3 -mos-
Amic=3- 03 —O E } 115 Ho p- 01 HE:=3.- R4 --CD101— R2
HIE:=3— R1
MAPLIN
OV
+5V o/p
111
BREAK CONTACT BD ISS.2
Figure 7. Track layout and component overlay of Break Contact Module.
Power Supply Unit Next refer to the parts list and Figure
12 and 13 for the PSU assembly. Mount the three resistors, three diodes, BRI, TRI, and REG I. Ensure correct orienta-tion of these components before sold-ering. Fit the 13 Veropins, C2 and C3 noting the polarity. Mount Ti with two 6BA 1/4" bolts, nuts and washers. Mount FSI using a V." x 6BA nut and bolt and three-way terminal block, using two 1" x 6BA bolts, nuts and washers. Wire T 1 to FSI and the terminal block 'N'. Wire the opposite end of FS1 to terminal block 'L'. Place systoflex sleeving over Cl leads, and fit to terminal block 'N' and 'L'. The battery clip (PP3) is connected to pin 5 (+ve lead red) and pin 4 (-ye lead black). The Ti secondaries con-
nect to adjacent pins 1, 2 and 3. Insert three 6BA x 1/2" CSK screws
through the cabinet base holes (Figure 15), at front left, rear left and rear right hand side. The two front right hand side holes are for mounting the micro switch. Insert two 1" x 6BA CSK screws and tighten all five with 6BA washers and nuts. Place the PSU PCB over the five screws and position the micro switch with the roller arm behind the angle bracket. Tighten down with two 6BA washers and nuts. Place a 6BA tag washer over the front left screw, and two 6BA washers over the remainder. Tighten down with three 6BA nuts. Connect a piece of wire from the 6BA (chassis earth) tag washer to terminal block 'E'.Wire the micro switch (Si) to
adjacent pins 12 and 13.
Break Contact Module Refer to the parts list and Figure 7
for the break contact PCB. The board is very simple to construct and requires no explanation. Once assembled, and checked, plug into any one of the six channel sockets on the main PCB. Ensure switches S3 to S8 are 'out' of circuit.
External Horn Refer to the parts list and Figures 8,
9 and 17 for the external horn PCB and wiring. Again, the construction is simple. Note the orientation of the tantalum C2 and FET TR1. The crinkle heatsinks fits over TR2. Do not connect to main PCB at this stage.
BURGLAR ALARM PSU
ISSUE 2
•
• •
•
•
Figure 6b. Track layout of PSU PCB.
8
Testing Place a 20mm, 100mA fuse into FSI
position. Connect a length of three-way mains cable to the PSU terminal block. Ensure Si is fully operated, and that no other wiring is connected to the PSU. Place a voltmeter between OV pin 6
and +15V pin 7. Apply mains power to the PSU, and check for a reading of 15V DC. Check for +5V between pin 6 (OV) and pin 8 and between OV and pin 11 when Si (micro switch) is released (slacken 2BA bolt). Re-operate Si and check for OV on meter. Remove the mains supply. Connect 22" of six-way ribbon cable
between the PSU and main PCB as follows:
PSU To Main PCB (OV) P6 P19 (+15) P7 P20 (+5) P8 P21
LED1 P9 P10 P22 P23 (Si) PI1 P24
Set the meter to 'amps' range and connect to pins 4 and 5 (or battery clip). Re-apply mains power and check for a reading of approximately 4mA and ensure LED 1 lights up. Remove the meter and LED 1 should extinguish. If the standby batteries are to be used, connect the nicad pack to the PP3 clip. A voltmeter connected across pins 4
and 5 should indicate a reading of between 7.2 to 7.8V depending on the batteries state of charge. Note that LED1 will stay on with the batteries part or fully charged, also an incorrectly placed battery, within the pack, will allow LED1 to stay on, but the reading across pins 4 and 5 will be lower than +7V. (Rectify immediately as nicads do not like short circuits or reversed connections placed on them.) For reliability, ensure that the bat-
tery pack is fully charged before use. The trickle charger keeps them topped up over a period of time and is not a fast charger.
Main PCB With power on, and keyswitch dis-
armed, LED1 only should be on, and no alarm tones heard. Ensure RV1 and 2 are both fully clockwise, and turn key to 'set'. A high pitched tone will sound immediately lasting for no more than two seconds. When the tone stops, LED9 ('ARM') comes on, showing that the alarm is now primed and ready. Note that the warble tone, sounds for the duration of the exit timer delay period and is presettable by adjusting RV I anticlockwise. The PCB legend has 'scaled' from 0 to 6 minutes and the small circle, on top of the cermet pot, acts as a pointer. If the exact time out periods are required, check the calibra-tion scale with a watch or clock. Once LED9 has come on, further
adjustment of RV1 will only be effective when the key is turned to 'disarm' and then back to 'set', starting the exit timer again.
Figure 8. Track layout and component overlay of External Horn PCB. Figure 9. External Horn wiring diagram.
S9
LED9
141
00 0 00 0 00 0 00 0 00 0 00 0 1 2 3 4 5 6 78 9 101112 131415 161718
33 34
31 32
29 30
RT
S8 S7 S6 S5 S4
Mins. 3
5. .1
6. •0
RV1
Exit Timer
Mins.
3 27 28 4,, • .2 Entry
5. .1 Timer
8. -0 RV2
25
26
190 200 210 220 230 240
4;70
"Pole
52
6 7 8 9 10 11
Figure 10. Main PCB wiring diagram.
Figure 11. Indicator LED mounting.
1 6BA Csk Screw, 11/4 6BA Spacer, washersI21. nutsI21. in 5 pos'ns
Main PCB
Lid LED
Figure 12. Mounting of Main PCB to cabinet door.
9
NcN C
k a
Keyswitch 59
Figure 13. LED lead outs.
33
Keyswitch S9
0---Artj 0
0
lal
Disarm Mode
34 1- 7 1D---34
33
Spare contacts
o
Ibl
Arm Mode
Spare contacts
Figure 14. Key switch wiring.
Points Connect a length of wire from P21
(+5V) to test point 1 (TP1). Operate S3 to the "IN" position. Press S2, display on and release. Channel 1 LED 3 will come on. Place S3 to the "OUT" position. LED 3 will go out. Repeat the above tests from +5V to TP2 to 6 and S4 to 8 checking channel LEDs 4 to 8. Note that pressing S2 allows the channel LEDs to light up, once triggered, for approxi-mately 90 seconds. S2 will have to be re-operated for a continued display etc. Remove the test lead from the test
point, but leave attached to +5V. Turn the key switch to "set". Once the "armed" LED has come on, place switches S3 to S8 to the "IN" position (note — remove any plug-in PCBs). Check that no tone is heard and that LEDs 1 and 9 only are on. Touch the +5V test lead to test points 1 to 6 in turn, all channel LEDs should come on, followed by a slow, two-tone alarm signal. Ext/Cab alarm, LED 2, will come on, indicating tht the external horn trigger circuit has been operated. This alarm tone continues until the key switch is set to "dis-arm". Leave the alarm sounding and check that after 90 seconds the display goes off (preserv-ing batteries on standby). The alarm tone should still continue. Press S2, check original display is returned.
Connector block 2x V' 6BA Bolts.
/ washers. nuts
\ 3x 1/ 2' 6BA Csk Screws. washers 151. nuts 161
Fuseholder 1x 1/ 6BA Bolt. nut
6BA Tag
Transformer kflicroswoch 2x lie 6BA Bolts. 2x l'6BA Csk Screws washers. nuts washers 14I.nuts 141
PSU PCB
Figure 15. Mounting PSU PCB and components
Temporary Test Connections Only
Break Contact PCB
Channel 1
Figure 16. Testing Break Contact Module.
10
Circuit Monitor Turn the key switch to "dis-arm".
The tone and all displays will be cancelled. Note that in the dis-arm mode and with S2 pressed, the unit gives a useful monitor facility of doors, windows etc, which can be checked before arming the system. Loosen the 2BA bolt holding off micro switch Si. Ensure the roller arm releases, and turn the key switch to "set". After the time out period and LED 9 has come on, the Ext/Cab alarm LED 2 will light, showing that the cabinet has been tampered with, and the alarm tone will sound. Reset the key switch to "dis-arm". The alarm tone will cancel, but LED 2 will remain on for 90 secs; display timeout. Re-operate Si by tightening the 2BA bolt and LED 2 will go out.
Ext. Alarm Place a short circuit across test
resistor RT (1k0) between pins 29 and 30. Press S2, LED 2 will light, indicating that the external loop sensing circuit has been tampered with. Remove the short circuit; LED 2 will go out. Remove one end of resistor RI and press S2. LED 2 will, again, come on. Re-connect RI and LED 2 should go out. Turn the key switch to "set" and
replace the short circuit across resistor RT. When the alarm sounds, remove the short circuit. LED 2 will stay on and the alarm will continue to sound. Return key switch to "dis-arm".
Power Failure Note that if standby batteries are
fitted and mains power is removed, LED I will go out. If the alarm unit is set and armed prior to removal of mains power, the system will stay armed, unless triggered appropriately. When running on standby power, the alarm tones will be slightly quieter than normal.
Entry Timer Set RV2, entry delay timer, for the
required time out period. Turn the key switch to "set" and trigger any channel (+5V to a test point). The selected channel LED should come on and stay on. The alarm tone will not be present until the time out period has been reached, then the alarm tone will sound and LED 2 will light. Reset the key switch.
Break Contact PCB This module may be plugged into
any of the sockets in channels 1 to 6 on the main PCB. Note correct orientation of the module, when fitting; the com-ponent side is to the right and the track side, to the left. Remove all power to the system,
turn the key switch to "dis-arm" and S3 to S8 to the "OUT" position. Connect two test resistors, Rh I and RT2 (22k) between pins 17 and 18 and pins 16 and 18, as shown in Figure 16. These resistors are used for test purposes only and will be removed when the circuit is to be used. Connect a voltmeter between TPA,
on the module, and a convenient OV point, with the +ve lead to TPA. Apply power to the system, and adjust RV1 for a reading of half the supply rail, i.e. +2.5V. Repeat the test on TPB using RV2,
and remove meter. Re-connect the meter between OV and TP1 to 6 (main PCB) depending on channel chosen for setting up the module, and check for OV. Short circuit resistor RTI, and check for +5V on the appropriate test point (main PCB). Remove the short circuit and repeat the test for RT2. Set the chosen channel switch (S3 to S8) to the "IN" position. Turn the key switch to "set" and remove one end of Rh. The appropriate channel LED will come on etc. Re-connect Rh; reset the key switch and repeat the test for RT2. Reset the key switch and remove
test resistors Rh I and 2.
External Horn PCB Figures 8 and 9 show the connec-
tions for using an external horn. For test purposes remove all power from the system (disconnect all batteries) and wire the PCB to pins 29 and 30 (remove resistor RT). Any changes made to these connections will trigger the alarm so ensure correct wiring. Connect the electronic siren to pins 3 and 4; the black lead is negative and the red +ve. Since the siren is inside a box, its own cover is not required and should be removed to assist wiring and make the sound output as great as possible. Connect batteries B1 and B2 to pin 5 (+ve) and 6 (-ye). The battery supply should be 12V and various types of dry cell (6V each) are available. Note that no charging current is available to these batteries.
The horn (H2) will sound im-mediately, so return power to the alarm unit as soon as possible. Place a short circuit across pins 29 and 30 (main PCB); H2 will sound. Remove the short rcuit and H2 will cease. Turn the key switch to "set" and
repeat the test. Both internal and
Continued on Page 31
Siren I louvred cover is omitted for easy wiring I
Ext. Horn Box
Back Panel
Ext Horn PCB
2 x6BA 1/2 Bolt •
washers &nuts
2 x6BA 1 /2 Bolt.
6BA 1/4" Spacer.
washers &nuts
Grommet
10x h106 1/;' Self tappers
Figure 17. Assembly of External Horn Box.
lal 2 wire system for any N2of contacts.
Loops not used
(e°
22k ---C D-01/P 2
1 22k
0 0----- { =1-OV VP1
1
VID2 22k ,OV _)31 liP 1
Ibi 4 wire system for any N2 of contacts.
22k 22k 22k
22k
22k
id i 4 wire maximum
l/P 2 22k QV
i/pi 0
22k
etc.
etc.
These resistors to be positioned close to contacts
security system, upto 5contacts only.
la I With Magnet in place.i.e. door/window closed, switch is operated& contact made.
IbI With Magnet removed i.e. door/window open, switch is released & contact broken.
Figure 19. Reed switch connections.
Window pane
2 x
Foil Terminating blocks YW51F
Foil
YW50E
22k to l/P1 or2
to OV
Figure 18. Methods of wiring alarm contacts. Figure 20. Window foil connections.
11
BURGLAR ALARM MAIN PARTS LIST Resistors — all ¼W 5% carbon unless specified R1,2,12.22-30 100k R3,5.7.17.18, 20.32,42
R4,6.21,33.35-4I R8 R9 RII R13,14.31 R15 R16 R19 R10,34 R43 R44 R45,46 RT (test resistor) RV1,2
Capacitors C1,2.7,11,12 C3,5 C4.6 C8 C9 C10 C13
Semiconductors 01-20 TR1,5 TR2,3,4,6,7 IC1.4-10 IC2,3 ICII
Miscellaneous LED 1-8 LED 9 S2 S3-8 S9 H 1 SKI 6
As required
10k 1k 470R 220R 120k 1M 68k 22k 470k 47k IM2 10% 1k2 3k9 1k 1M cermet
100nF disc ceramic 27nF polycarbonate luF 35V tantalum 82nF polycarbonate 820nF polycarbonate 330pF ceramic 47uF 10V axial electrolytic
IN4148 EIC2141 BC548 4001 BE 4020 BE 4050BE
Mini LED red Chrome LED small HQ push switch SP slide switch Keyswitch Piezo horn 8-way edge connector Burglar alarm main PCB 6BA x 1" csk screw 6BA washer 6BA nut 6BA x V." spacer 6BA x 1/2" csk screw 2BA x 1" bolt Grommet small Burglar alarm boX Veropin 2141 Ribbon cable 10-way 14-pin DIL skt 16-pin DIL skt
Door contact reed Window foil Window foil terminals Surface mounting reed Door loop Pressure mat
For kit see under PSU parts list
12 off (M100K)
8 off (MIOK) 11 off (MIK)
(M470R) (M220R) (M120K)
3 off (MIM) (M68K) (M22K) (M470K)
2 off (M47K) (M1M2) (M1K2)
2 off (M3K9) (MIK)
2 off (WR45Y)
5 off (BX030) 2 off (WW34M) 2 off (WW60Q)
(WW40T) (WW52G) (WX62S) (FB38R)
20 off (QL8013) 2 off (QB62S) 5 off (QB73Q) 8 off (QX01B) 2 off (QX 11M)
(QX22Y)
8 off (WL32K) (YY59P) (YR67X)
6 off (FF77J) (FH40T) (YW52G)
6 off (FL83E) (GA45Y)
5 off (BF13P) 12 off (BF22Y) 12 off (BF18U) 5 off (FW34M) 2 off (BF12N) 2 off (BFO1B) 2 off (FW59P)
(XGO6G) 40 off (FL21X) 1M (X1,106G) 8 off (BLI8U) 3 off (BL19V)
BURGLAR ALARM PSU PARTS LIST Resistors — all VAN 5% carbon unless specified RI 220R R2 10k R3 6k8
Capacitors C 1 C2 C3 C4
Semiconductors 01.2,3 BR I Reg 1 TR1
100nF suppression capacitor 2200uf 25V axial electrolytic 100uF 25V axial electrolytic 100nF disc ceramic
1N4001 W005 uA78L05AWC BC214L
(YW46A) (YW50E) (YW51F) (YW47B) (YW48C) (YB91Y)
Miscellaneous Ti Si FS1
Transformer 6-0-6 100mA Microswitc h 20mm Fuse 100mA Chassis Fuseholder Terminal. block 5A (3 sections) Burglar Alarm PSU PCB 6BA TAG 6BA x 1" bolt 6BA x V bolt 6BA x 1" csk screw 6BA x 1/2" csk screw 6BA washer 6BA nut Insulated sleeving Veropin 2141
Standby Power if required B1 -6 Nicad 'AA' cells
Battery box Battery clip
2 off 3 off 2 off 3 off 13 off 15 on 3" 13 off
(WI300A) (FH950) (WROOA) (RX491)) (HF01 8)• (GA44X) (BF29G) (BFO7H) (BFO5F) (BF13P) (BF12N) (BF22Y) (BF18U) (BF87U) (FL21 X)
6 oft (YGOOA) (HQ01B) (HF28F)
A complete kit is available which includes all the parts in the PSU parts list (including standby power parts) and all the parts in the main parts list excluding those listed under As required.' Order As LW57M (Burglar Alarm Kit) Price £44.95
EXTERNAL HORN PARTS LIST
Resistors — all %W 5% carbon unless specified R1.5 lkO R2,4 100k R3 IMO
Capacitors Cl C2
Semiconductors TR1 TR2
Miscellaneous H2 1312
100nF disc ceramic luF 35V tantalum
2N38I9 BC441
Electronic siren 6V lantern battery Heatsink 5F PCB Veropins 2141 Case Grommet small Screws self tapping No 6 1/2 inch Bolts 6BA 1/2 inch Washers 6BA Nuts 6BA Spacers 6BA 'A inch
2 off (M1K0) 2 off (14.4100K)
(M1M0)
2 off
6 off
10 off 4 off 4 off 4 off 2 off
(BX03D) (WW60Q)
(QR36P) (QB70M)
(XG14Q)
(FL78K) (GA47B) (FL21X) (XGO7H) (FW59P) (BF67X) (BFO6G) (BF22Y) -(BF18U) (FW34M)
A complete kit of all the parts listed above (excluding batteries) is available Order As LW58N (External Horn Kit) Price £29 95
BREAK CONTACT MODULE PARTS LIST Resistors — all i,1W 5% carbon unless specified R1,2,6,7 2k2 R3,4.8,9 100k R5,10 180k RT1.2 (test resist.) 22k RV1,2 22k vert-sub min preset
(M220R) (M10K) Capacitors (M6K8) C1.2
(fF561) (FB90X) (FB49D) (13X030) Miscellaneous
TPA.B
3 off (QL73Q) (QL37S) (QL260) (QB62S)
Semiconductors D1-4 IC1
100nF disc ceramic
1N4148 40118E
Veropin 2141 Break contact PCB 14-pin OIL skt
4 off (M2K2) 4 off (M1OOK) 2 off (M180K) 2 off (M22K) 2 off (WR72P)
2 off (BX030)
4 off (1)L80B) ' '(QX05F)
2 off (FL21X) (GA46A) (BL18U)
A complete kit of parts is available Order As LW59P (Break Contact Kit) Price £2 99
12
Prices shown here may have changed after 14/8/82
MULTI-MODE DIGITAL sroP STOPWATCH wiir cH * Accurate to 100th of a second. * Large, eight digit display. * Times up to 24 hours can be displayed. * Four modes of operation: Standard, Sequential, Split and Rally.
by L. Harrold
This electronic stopwatch is a com-prehensive timer which is more robust than a mechanical stop-watch and can measure accurately to 100th of a second. It has a remote start/stop facility which enables it to be triggered by the interruption of a light beam or the sound of a starting pistol etc. The stopwatch has a large LED
display which can be turned off while the clock is running to save battery power. It has four modes of operation: Standard - each timed event starts from zero, Sequential - the time be-tween each operation of the start/ stop switch is displayed (lap times etc.), Split - the timer counts continuously although timings can be displayed whilst this occurs, Rally - the same as Standard except that the clock is not reset to zero but continues from when it was stopped.
Circuit The circuit diagram of the stop-
watch is shown in Figure 1. The main component is the Intersil ICM 7045 IC which contains an oscillator, high fre-quency divider, low frequency counter, latches, multiplexer, decoder and con-trol circuitry. The oscillator frequency is set by the external crystal and trimmer capacitor to 6.5536 MHz. This is divi-ded down to 100 Hz to drive the low frequency counter. The counter out-puts are connected to the latches so that the display can be held and read while the counter is still running. The outputs from the latches are multi-plexed to drive an eight digit com-mon cathode display. The ICM 7045 also contains the seven segment de-coder and the digit and segment drivers so that the display can be connected directly. The 4093 and associated compo-
nents provide de-bounce circuits for
the push switches. When a push switch is operated it discharges the capacitor in less than one millisecond. The two Schmitt trigger gates change state which takes the appropriate pin of ICI low. The Schmitt triggers are inhibited until the capacitor has re-charged. The time constant of (R1+R2) and Cl is large compared to the bounce time of the switches. The remote control input switches
5V which turns on the transistor and therefore has the same effect as the start/stop switch. The eight digit dis-play can count up to 23 hours 59 minutes 59.99 seconds. After this the display carries on counting from zero. The reset button sets the counter to
zero, i.e. displays two zeros in the decimal part of the seconds. The seconds, minutes and hours part of the display are blank and remain so until that part of the display is not zero. The display switch turns the LED display on and off. With the display on the current con-
sumption is 70 to 130mA. depending
on how many digits are on. When the display is off the consumption drops to a maximum of 2mA. Therefore if nickel cadmium batteries are used, which have a capacity of 500mA hours, this should give a life of several hundred hours. The start/stop switch controls the
counter and the four position switch selects the mode of operation.
Construction The components are mounted on a
single sided PCB and should be fitted as follows. The LED displays first: Note that on the side of the displays, that the 'M' of the code number is nearest to pin 1. IC holders should be used, especially for Id, and these are fitted next. When the click switches are viewed from underneath, one side hasa flat, and the PCB legend shows correct mounting orientation. The crystal and trimmer capacitor C5 are mounted next. The crystal should be folded over flat next to the PCB. Next the resistors can be fitted and the switches wired.
13
3 1 2 10 1718
DISP 4
14 13
8 1516 1 2 3 10 11 17 18 6 s 5 8 16 i
DISP 3
14 13
IC1= ICM7045 IC2 = 4093BE
14
BC 548 Viewed from
below
28
15
1 2 10 1 1718 56 815 16
DISP2
14 13
2 10 1117 18 6 1
DISP 1
14 13
' Cl 1000uF
4
1= Standard 2=Sequential 3=Split 1 4= Rally
8 10
23
412 13 14 16
6 25 24 22 21 18 26 3
iC 1 2
15 17
11 9 20 1928
-1
614
C5 65pF
18pF
IC2b
400 :1_
2
5 6
S4 Mode Select
C4 IC2 C2 C3 111.100nF PIN7 100nF
IC2 PIN 14
1 K.n . 121
8
IC2c
R1 68k
R4
I 1k
IC2a IC2d 2
12 R2 110 1
• (- 1
13 1k
0 8
S3
— 0 0— Reset
R3 68k R5
4k7
BC 548
R6 4k7
10
Display Start/ Stop
9
REMOTE CONTROL I/P
Figure 1. Circuit diagram of stopwatch.
Capacitors C2 to C4 and TR1 should be mounted and bent over at 45 degrees to give enough clearance for a front panel. Finally the wire links are wired and soldered, and Cl fitted underneath the PCB. The LED display is improved considerably when viewed through a red filter and it is recom-mended that one is used.
Setting up For accurate timing the crystal
should run at 6.5536 MHz and is adjusted by C5. If a frequency counter is available, this is easily checked without loading the oscillator as follows. A 10k pull up resistor should temporar-ily be connected between pin 22 of ICI and the positive supply. The display should be switched on and the counter reset. The frequency on pin 22 should be 800Hz. To get the required accuracy, the frequency counter should be switched to period and the period for 14
one cycle measured as 1250.00 micro-seconds. Adjust the trimmer capacitor to give the right frequency. If a fre-quency counter is not available, then C5 should be set half way and the stopwatch checked over several hours, using the radio or speaking clock. C5 can then be adjusted accordingly; more capacitance to slow the stopwatch down.
Operation Standard Mode 1. Press the reset switch to zero the counter.
2. Start the counter by pressing the start/stop switch.
3. Stop the counter by again pressing the start/stop switch. The time is now displayed. When start/stop is pressed again the counter is momentarily reset then starts tim-ing another event. In this mode the display can be turned off.
Sequential Mode 1. Reset the counter. 2. Start the counter. 3. Press start/stop to read the display. This time is held on the display but the counter continues running. When start/stop is next pressed the time since it was last pressed is displayed. This enables lap times to be taken. The display cannot be turned off in this mode, however, if standard mode is selected it can be, but remember to switch back to sequential mode before press-ing the start/stop switch.
Split Mode 1. Reset the counter. 2. Start the counter. 3. Press start/stop to read the display. This time is held on the display but the counter continues running. Each time the start/stop is pressed the display shows the total time since
i DISP 4 DISP 3 DISP2 DISP 1
05
PI
ICI
F:3 R2
R4
5 1
03 L.)
1 1 1) 11)11T1,0
9 ? 9 [I] i 1(2 ij TR1 9 0 0 10 ;
S5
ON/OFF
NB:- For easier wiring, pins should be inserted on component side of PCB
3 2 A 4 12
Os 110 60 Oc
06 100 7 8 9 0 0 0
S4
Mode Select
S3
Reset
Figure 2. Component overlay and wiring diagram of stopwatch
the start/stop was first pressed. The count can only be stopped by pressing reset. The display can only be blanked if
the same procedure as described for the sequential mode is carried out.
STOPWATCH PARTS LIST Resistors — all 'AW 5% carbon unless specified R1,3 68k R2,4 I k0 R5,6 4k7
Capacitors Cl C2,3.4 C5 C6
Semiconductors TR I ICI IC2 XI
1000uF 10V axial electrolytic 100nF polyester Trimmer 65pF 18pF ceramic
BC548 ICM7045 4093 BE Crystal 6.5536 MHz
Rally Mode 1. Reset the counter. 2. Start the counter. The reset switch is now automatically disabled thus preventing accidental resets during long timing intervals.
2 off 2 off 2 off
(M68K) (MIKO) (M4K7)
(FB81C) 3 off (BX76H)
(WL72P) (WX47I3)
(QB73Q) (YY938) (QW53H) (FY90X)
Miscellaneous DISP1 -4 S1,2 S3 84 S5 131-3
3. Stop the counter. 4. Press start/stop again allowing the counter to continue. The display can be turned off in this
mode.
00 display type C Click switch Push switch 3 pole 4 way rotary switch Sub-min toggle 'A' Ni Cad AA 4V5 battery box PP3 clip Veropin 2141 Click cap blue Stopwatch PCB Knob Knob cap blue OIL skt 28-pin OIL skt 14-pin Filter red
4 off (BY68Y) 2 off (FF87U)
(FH59P) (FF75S) (FHOOA)
3 off (YGOOA) (YR6IR) (HF28F)
10 off (FL21X) 2 off (FF89W)
(GA04E) (YG40T) (QYOIB) (B121X) (BL18U) (FR34M)
A complete kit for this project is available Order As LW65V (Stopwatch Kit) Price £.34 95
Price shown here may have changed after 14/8/82
15
DIGITAL MULTI-TRAIN CONTROLLER by Robert Kirsch
* 14 locomotives individually controlled on the same track
* Any 4 locomotives controlled simultaneously
* Automatic short circuit protection
* Supply always present for carriage lighting etc.
* Remote control and computer interfacing
* Low cost, two wire system
Railway enthusiasts have for many years appreciated the need for a control system that enables trains to be driven as if the operator were in the driving cab of the loco-motive. This not only means control of speed and direction of that locomotive, but also the ability to move anywhere on the layout without the need for track isolating or. switching, thus making the wiring of the layout much simpler. The system described in this article
fulfills all these needs by producing a constant 18V DC on the track with digital information superimposed on it, to which only the selected train or trains will respond. The permanent track voltage also means that locomotive headlights, carriage lighting and many accessories may be used unaffected by the speed of the trains. This system can control up to 14
locomotives all on the same track, and any four of these may be driven inde-pendently at one time. Provision is also made for any or all, of the four control units to be operated by a 7 bit digital input, thus enabling remote control either from hand-held units (using wire or radio) or from a home computer, giving full control of direction and speed. Details of the remote control and
computer interfacing will be described in later articles.
Circuit Description Refer to Figures 1 to 5 when follow-
ing the circuit description. The most important consideration
in the design of a system like this is to keep the receiver module as small as practible to enable it to fit in as many 16
locomotives as possible. This has been achieved by using a small 8 pin IC, the ML926/7, IC1 as the receiver. Decoding and control is accomplished by IC2, a 40106 CMOS IC leaving two transistors, TR2 and TR3 as input amplifiers, the six transistors TR4 to TR9 for motor control and one tran-sistor, TR I as a voltage stabiliser. The ML926 and ML927 are pulse
position modulation (PPM) receivers with built-in error detection circuits There are four outputs from each IC, three of which are decoded by IC2 to control one of the seven receivers. (000 is used as the all off condition.) The fourth output is used to control the
4;4;
direction of travel. A fifth bit is trans-mitted by the control unit to select either the ML926 or the ML927 ICs, thus giving fourteen channels. As it is only possible to decode one
signal at a time the receiver is addressed for one period out of four (called its time slot) and it retains the information received until the next address is due. The speed of a locomotive is con-
trolled by allowing any number of coded time slots (from 1 to 10) to be trans-mitted during a period of 10 time slots (TS), thus controlling the on to off ratio of pulses fed to the motor. Minimum speed is with one TS pulse and nine
AC Mains —
Alarm
Reset —
Track 41
P SU
Protect. CCT
Power Transistor
Oscillator
Emmiter Follower
Stabaliser
Ripple Counter
Output Latch
Clock
— V ref
Bridge Rectifier
1111
+192
PPM. Modulator
Input Scanner & Sync.
1 to4 Counter
5 Lines
— TS4 —TS3 —TS2
TS1
1 to 10 Counter
V A
Speed Control
Latch
Gate
Direction
Group
Diode Encoder 1 of 7
Pulse Stripper & Amp.
Voltage Stabaliser
PPM. Receiver
1 of 7 Programmable-10--Decoder
Motor Control
from Control Units
Power Transistor Bridge
Figure 1. Block diagram. (a) Common and control boards. (b) Receiver.
blank periods, half speed is with five TS pulses and five blank periods and full speed is with a continuous string of TS pulses being sent thus keeping the motor driven at full power. The transmitter IC normally used
with the ML926/7 is the SL490 but several of the built in features of that IC make it undesirable to use in this application. The PPM system uses a frame of six
pulses followed by a sync period. Digital information is transmitted by varying the time between two consecutive pulses in the following ratio: DATA 1 = 2, DATA 0 = 3, SYNC = 6. The pulse timing is controlled by
resetting a counter IC4 after 2, 3 or 6 clock pulses have been received de-pending on whether the data to be sent is 1, 0 or sync. In order to transmit each one of the five data bits in their correct
order another counter, IC8 scans the five AND gates IC3c and IC7 in turn and then at the sixth count causes the sync period to be sent at the same time resetting the counter for the next scan. The timing point of the pulse to be transmitted is detected by monitoring the resetting point of this counter. This causes the latch IC3d to be triggered which allows a pulse of twice the clock period to be sent. The ripple counter, IC5 provides all
timing pulses required by the con-troller. It is fed by the CMOS relaxa-tion oscillator formed by IC6 a,b,c and d. This oscillator is divided by 192 by IC5 to produce a IS trigger pulse approximately every 850us. Each frame of data takes about 380us, so that two complete frames can be sent in one TS period. The trigger pulse denoted above is
used to clock the counter IC9 and produce four separate, consecutive output pulses, TS1-4 each approxi-mately 850us long. Each of the four control boards is fed with one of these TS pulses and this pulse is used to step the counter IC1 (control board). The counter steps from one to ten and then resets itself for the next count. The first output from the counter sets the latch IC2b and c which is reset when the counter reaches the number set by the speed control thus holding the latch open for one to ten pulses. The latch gates TS pulses which are fed to the diode encoder. The pulses are con-nected onto one or more of the three data lines depending on the code of the receiver being addressed. If the reverse switch is operated or group 2 is selec-ted the TS pulse is switched onto the appropriate data lines.
17
LEDI
Si FS1 Ti 3 D1
F1N5400 2 9
FS2
RI
1k
03
12V
4 02
N -0
L
E
D5-15 1N4148 ICI uA74Ic IC2 uA78LI2AWC IC3,7 40818E IC4,8,9 40228E IC5 40408E IC6 4001BE
TS1 0
TS2 08 10
TS313
TS4 011
OV
IC5
09 10
4 7
• 13 11
16
R15
10k
IC6d
1N5400 1
2A
0
C1 11111 4700uF
R9
2k2
0 C6 10 u F
04 20V
R8
22k C5 10nF
6
4 ICI
R14 10k
R7
2k2 TR3
C13 100uF
R3
1k
R13 100k
12 IC6a
C10 T 33p,
+12V
OV
7
11 15 14 2
3 16
13
IC9
De
Li 21
2A
TR2 T1P122
Re
C4 220pF
R4
3 5 N • D6 i2 IC3d
11 5 IC3
14 b ;__;j_— )46 4 D i 13
• •
1 D7 RI2 7 —.---4— y _Di _ e_40 _ 4 =
/;1115 33k
16
IC4 2 05 10k IC3a
1k
Ca R10 100nF •1 4k7
0.22R R5 1k
TR1 BC327
R2 2k2[
0 V
IC2 in
joC2
TOOpF 20
c°r" T I out 18
R11
10k
TR4 BC548
ale C7 100nF 1
+12V
IC6b
R17
4—I 1--100k
ICs3.667 PIN]
12
IC6c
D15
Ki IC3c
D14 Ki 10 ( 1 _8
IC7c 8
013 13 K i 11
012
KJ IC7a
D11 4(
IC7b
ICs 3,657 PIN 14
5
R18
100k
R19
100k
R20
1- 1 10011( R21
r— i 10011 R22
100k
s 11
15
2 4 14
8 13
16
IC8
+I2V
OV
19
15
Oc
16 QB
a
> c7)
S2
Reset Power /Test Alarm
Q.
0
Figure 2. Common board. PSU circuit diagram.
Completed control PCB.
18
The DC supply fed to the track is stabilised by ICI (common board) at about 18V and data signals from the emmiter follower TR4 are superim-posed on it and used to control the power Darlington transistor. TR8 which supplies current to the track. In order to protect the controller from damage due to accidental short circuiting of the track the current flowing through R6 is monitored by TR1. When this current exceeds the preset limit the transistor conducts and fires the SCR TR3 thus removing the drive to TR2 and turning off the supply to the track.
A
+12V
0 V
TO TS1,2,3or 4
14 Li
13 0 4 12 0
0 11010 0 6
07
• 0
90
0
• 5
4'
0 -1' 14 8 16 13 Cl 15
3 2 4 10 5 6 9 11
Id 1 47uF
IC2
V CM 0 0 0 0
3 c.,.3. . 15 2,94
2
-03
SZcg,
8 0 4
2
0
56 S2
1
m CV 0
S7g,
2
6 7
0 9
0 80
90-
100,,
0 PIN 14
75
L 2
Speed
R4
I
ZS ZS.,
0
4
2
I
EN °ZS L--4,
6
S1
d, °ZS --.
0
0
E-
--.
ZS
I) 9 0—'• I IC2b 100k 0 O Train Select LKA D15
5 IC2c 4 10
C2
— I
R3 100k
10 ! - -41R1
. 100k 100k
R2 D16
3k32,1 IC2a
12 IC2d
- F )81
08
f ....)
2 13
IC2
D1-26: 1N4148 IC1. 4017BE
III. PIN 7 Group O
S4 S3 Direction
a D14
12 i IC2 . 4001UBE 0 x• 02 ix cc ___ _.r-%_
L KB D13
Figure 3. Control board circuit diagram.
r- 4.4us
Clock ELF111111—L111111J Enable
Tx pulse
Tx latch
1
Clock +192
Figure 4. Timing diagram.
Reset IC441LOGIC 1 trip Tx latch
n LOGIC 0
Advance I/P selector
IC8 1step
IS pulses corresponding to half speed.
Drive to
Loco motor
IS TS IS TS TS
L-0 85ms
Ibl
41RESET
19
10k
R9
R10
R11 4
0
0
c7 ,
Track Pickup
0 0
0
Figure 5. Receiver circuit diagram.
20
The SCR remains latched until it is reset by shorting it with S2. If the fault is still present the circuit will trip imme-diately and cause no damage. When the track supply falls more
than 12V below the power units output, either due to the protection circuit being tripped or due to a fuse failure the indicator LED1 will light. Provision is also made for a buzzer to be fitted if an audible indication of track supply failure is required. A timer may be used to reset the protection circuit auto-matically after a short delay and this will be described in a later article.
Construction Build all PCBs referring to legends
and parts list.
Common Board The track layout and component
overlay for the common board are shown in Figure 6. Fit Veropins and PCB mounting fuse holders and solder. Ir sert and solder all resistors, diodes capacitors and the choke. Insert the tw plastic transistors, regulator and SCR into their correct positions. Push the leads of the power transistor TR2 through the PCB just far enough to allow it to be soldered and bend the leads as shown in Figure 7. Finally, insert and solder all ICs observing the usual CMOS precautions and making sure that they are the correct way round.
MAPLIN TRAIN COMMON PCB
0 0 1 ? nv
. . E 3 r
0 4 "
0
+12V
0 7
0 8
0 9
01° 0 11
012 OV
R20
it 411 0:—°0/ffoi /Ti\!L
20 R2 2 CI 0 19 09 18 b eTR2
Cl —C =1— des‘21 TR3 •
‘.." L1 k a C4 0
R6
IC8
co
co
C3 N. •TR1
I R3 R4
[ ]C9 —
I
II I c-) IC7
ic- 0 D1 4- - ,_
011
cc
1 -1 1— 1: 0 0 0 0 0 R21 T 1 15 16 17
JL
IC1
.1111
IC3 C7 • NTR4
E ri
GA 72 P
IC 5 T1 1)15 R17 = IC10 — C =1— R1t) Figure 6. Common board track layout component overlay.
21
Receiver board 1 installed in diesel locomotive.
Receiver board 1 installed in tender drive locomotive.
Control Board The track layout and component
overlay for the Control Board are shown in Figure 8. Fit and solder all compo-nents in order as described above but in this case fit the Veropins from the component, side of the PCB to enable ease of wiring when the boards are fitted to the front panel. The rotary switch without the click stops is mounted next to IC1. Note the unused component positions on the board are for the remote control option which may be added later.
Assembly Mount the transformer, mains
switch, fuse holder, LED, push button and terminals on the case. Fit the common board and control boards. (Note that only one control board need be fitted initially.) The self-adhesive penal legend may be used as a template for drilling the front panel or the ready drilled case XGO9K may be used. Note that this is not included in the kit. Wire all boards and components
together referring to Figure 13. Insert the fuses noting that the 1 amp anti-surge fuse is fitted in the panel fuse holder. Receiver board There are initially two receiver
boards available to fit varying size locomotives. See Figures 10 and 11. The dimensions of these boards are shown in Figure 9. Fit and solder all capacitors and resistors noting that some resistors do not lay flat on the board. Insert and solder all diodes other than D3 to D8 and fit all transistors
taking special care with the positioning of TR6, 7, 8 and 9 as shown in Figure 10b/1 1 b. Insert and solder IC2. Decide which channel the receiver
is to use and insert the appropriate .diodes referring to Figure 12. If the receiver is to be group A then insert an ML926, if group B an ML927. Carefully check all soldering and positioning of components before testing.
Testing Procedure Controller Switch on power with nothing con-
nected to the output terminals. The neon indicator in the mains switch should now be illuminated. Using a meter set to 20V DC or above check that there is approximately 18V at the output terminals. Press the reset button and the
"Track Supply Fail" LED should light and extinguish when the button is released. If this test is satisfactory, short circuit the output terminals and the LED should again light brightly while the short circuit is present and dimly when the short circuit is re-moved. Press the reset button. The LED should be extinguished and 18V re-stored to output terminals. Receiver Connect the receiver to the control
unit as shown in Figure 14. Select the channel number and group of the receiver on a control unit and advance the speed control. One of the two lamps should light with its brightness de-pending upon the speed set. Switch over the reverse switch to the oppo-site position and repeat the test. In this
case the other lamp should respond. Switch the control unit to the other channels and groups and ensure that the lights remain extinguished. If these tests are satisfactory the module is ready to be inserted in the locomotive.
PCB
Transistor TR2
Mica Washer
Screw
Figure 7. Power transistor mounting.
56
48.3 approx
Receiver 2
109.3
Receiver 1 30 approx. .1
May be trimmed to10
Figure 9. Receiver board dimensions.
22
Figure 8. Control board track layout component overlay.
Receiver board 2 installed in tank locomotive.
11° 3
4 l Z ' fR?6 -
-R22-
-R2I- ,C2 a
TR5
B
-R20- z i ttsc it)
-
1 D10
vsNiso l
ert-Evu: ibti•••#••
04 0300050007 -4
GA74R TRI I DI
1:1 ct C2+ ,7 RI
l lt I **v.
FC CC CC
Receiver BD .1
TR8 1162
TR9 1162
/ in — R19 — 4ir TR1 r- cC• p., cc, -- D1 — IN" 1111, i \ - -9 1TR4.—.. 0 tog- U 3 \
(c) cc fi5 9 7-•\+ 04 0;.- .66 o ,
\ —R 20 -- ." i,Q11‘44,,,..
i cc' g,
.7,) gi31-5 Re
4
ill cC i—
\
/ 9 04 i ' '"" / '• 4110 -. +9 t 00
6 I '9N , gr.i. cio + tc ct cf 4fk )
t4 E cnr? E N. [-sir 0 0 ct
\ D16 1 GA75S C $ —R11. ( )2 cr C 3 i tC1 ct
BC 337
TR7 715
TR6 715
M ode sy mbol
CO4k
represents
BC548
0
2SA715 2SC1162
All viewed from below
- e -c b
Loco Insert Diode
1 04 06 07
2 D4 05 08
3 04 05 07
4 D3 D6 D8
5 03 D6 07
6 D3 D5 08
7 D3 135 D7
Group A ML926
Group B ML927
Figure 12. Receiver code chart.
Figure 11(a) Receiver board 2 track layout co mponent overlay. (b) Receiver board 2 transistor mounting.
Mains in
Mains ON/OFF
Si
FS1
6
Tag ' —
Ti
LED1
Blu &Yel
S2
Reset
Terminals
NC 0 Y 0 w Lij
CLI Cr CO Cr
TR 2
.3 2
Girel 5
+12V 6 • 7
TS1 .8
TS2 -•9 TS3 00 TS4 -. 11
12
15 14 13 12 11 10
OV
20 • 1TF 21 '1918
Common bd.
13 1415 161
I A CB
2.- - - --. 3.-- - _ __. .-- - --. .- - --. __
- 41......-- - -. ,-, , _ _. , • ._ ‘. 5.- _.7 -; 1, , ..- - - -. , i .- , 6 ...... I 1 s_ , I I ....,
9 ' - - - - I • T8 I /8 I i / 8
I I I I i...s ‘ I ,- • I
/ I '... I I I i I _ _
. / i j I ' •
i I I I -_ _ J L _,. L _ _ _ _
_ _ _ to TS2 - - - to TS3 - - - to TS4 Control 2 Control 3 Control 4
Control 1
Existing suppression capacitor
Wheels connected to chassis
Isolated wheels
Chassis connection
Figure 15. Wiring of conventional locomotive.
To pins 3d4 on Rec. module Ringfield type
motor
Remove
chassis connection
Double Worm drive motor
Ensure metal strip
iscut away from brush pivot
Add sleeving to insulate brush from spring
Pin1
Pin2
Figure 13. Controller wiring diagram.
24 Figure 16. Modifications to various motors.
Installing Receivers in Locomotives All locomotives designed for use
with conventional control systems have the two sides of the motor connected directly to the wheels on each side of the locomotive Figure 15. To install the receiver module, the motor must be completely isolated from the wheels. In many modern models this is accom-plished by removing a wire link but in some of the older models there is a permanent connection from one side of the motor to the chassis. In all cases by careful modification this connection
Isolated
wheels
Chassis connection
Wheels connected to chassis
Pins 38.4 Add sleeving to insulate brush from spring
Worm drive motor
spring
brush
can be removed. Some examples are shown in Figure 16. It is most impor-tant to ensure that the motor is com-pletely isolated and it is worth check-ing this with a meter set to ohms before installing the module. In most cases there will be a wire
coming from one of the pickups, this is connected to one input of the module and the other input is connected to the chassis at a suitable point as shown in Figure 17. After installation, if it is found that the locomotive travels in the wrong direction in relation to the controller switch, the wires to the motor should be reversed.
Figure 14 Receiver testing.
KIT PRICES Complete kits are available for the train controller as follows:
All parts in Train Common/PSU Parts List excluding the case (XGO9K) Order As LW61R (Train Common/PSU Kit)
Price £27.50
Ail parts in Train Control Parts List Order As LW625 (Train Control Kit) Price £6.45
Four kits are available to make receiver modules as follows:
Kit for Group A with long PCB Order As LW637 (Receiver 1-M1926 Kit)
Price £5.95
Kit for Group A with square PCB Order As LW64U (Receiver 2-141926 Kit)
Price £5.95
Kit for Group B with long PCB Order As LW68Y (Receiver 1-ML927 Kit)
Price £5.95
Kit for Group B with square PCB Order As LW69A (Receiver 2-ML927 Kit)
Price £5.95
Prices shown here may have changed after 14 8 82
Internal view of main control box.
25
To ensure reliable operation of this system, as with any other, the loco-motives should be in good condition, and it is often worth replacing brushes and cleaning wheels and pickups be-fore use. The track needs to be kept fairly clean although the receiver will respond to signals as long as there is enough power to drive the motor. The next article in this series will
describe the remote control facilities and computer interfacing. Future articles will describe track
circuiting (train position detection) point control and detection of position. interlocking and control of signals, automatic loop switching, and many other useful circuits as well as con-structional hints for the railway modeller. •
Diesel/ Electric Loco's
Chassis connection must be broken
Tender drive Steam Loco's
Rx Module
i i I I I I I L L i
5 co
II II I i ii II IL II
Ribbon cable
•3 Rx Module .4
Figure 17. Installation of receiver in locomotive.
TRAIN CONTROL PCB PARTS LIST Resistors — all '4W 5% carbon unless specified R1,3.4 100k R2 3k3
Capacitors CI C2
Semiconductors D1-26 ICI IC2
Miscellaneous Si S2 S3,4
47uF 25V PC elect lOnF polyester
1N4148 4017BE 4001UBE
Rotary switch 1 pole 12 way Rotary switch 1 pole 12 way special Sub-min toggle 'A' Veropm 2141 Train control PCB Knob K78 (for Si) Knob K7C (for S2)
3 off (M100K) (M3K3)
(FF08J) (BX70M)
26 off (QL80E3) (QX09K) (QL030)
(FF73Q) (XX45Y)
2 off (FHOOA) 15 off (FL21X)
(GA73Q) (YX02C) (YX03D)
TRAIN COMMON/PSU PARTS LIST Resistors — all V3W 5% carbon unless specified R1,3,4,5 lk R2,7.9 2k2 R6 0.22R (3W) wirewound R8 22k R10 4k7 R11,12,14.15 10k R13.17-22 100k R16 33k
Capacitors Cl C2 C3' C4 C5 C6 C7,8,9 CIO
4700uF 25V axial electrolytic 100pF ceramic 100uF 10V axial electrolytic 220pF ceramic lOnF ceramic 10uF 25V axial electrolytic 100nF polyester 33pF ceramic
Semiconductors 01.2 1N5400 D3 BZX61C12 D4 BZY88C20 D5-15 IN4148 TR1 BC327 TR2 TIP122 TR3 MCR102 TR4 BC548 ICI uA741C (8-pin) IC2 uA78LI2 AWC IC3,7 4081 BE IC4,8,9 40228E ICS 4040BE lC 4001E3E
(MIK) (M2K2) (W0.22) (M22K) (M4K7)
4 off (M10K) 7 off (MIOOK)
(M33K)
• (FB96E) (WX56L) (F848C) (WX60Q) (WX77J) (FB22Y)
3 off (BX76H) (WX50E)
Miscellaneous Li Ti LED 1 FS1 FS2 Si S2
RE suppressor choke 2A Torodial transformer 80VA I8V LED red Fuse anti-surge IA Fuse 20mm 2A Dual rocker neon Push switch Safe fuseholder 20 Fuse Clip S/R grommet Veropin 2141 LED dip Quickterm push Train common PCB Mains lead 10-way ribbon cable Wire 3202 black Wire 3202 red Train control case Kit 'Fr plas Bolt 6BA x 1/2" Washer 6BA Spacer 6BA x Ve" Nut 6BA Tag 2BA Small thermpath Train control front panel Stick-on feet
21 off
(HWO5F) (YK17T) (WL27E) (WRI9V) (WRO5F) (YR70M) (FH59P) (RX96E)
2 off (WH49D) (LR490) (FL2IX) (YY40T) (BW71N) (GA72P)
3M (XR04E) 1M (XR06G) 1M (XR32K) 1M (XR36P)
(XGO9K) (WR23A)
7 off (BFO6G) 3 off (BF22Y) 4 off (FW33L) 7 off (BF18U)
(BF27E) (HQ00A) (XX47B) (FW38R)
TRAIN RECEIVER MODULE PARTS LIST Resistors — all '4W 5% carbon unless specified R1.5,8-12 17 18 10k R2,13,14 100k R3,15,16 4k7 R4 47k R6 1k R7 18k (4W) R19-22 470R (14W)
Capacitors CI C2 C3
C5.6
Semiconductors DI
2 off (QL81C) D2 (QF55K) 03-16 (QH2IX) BRI
11 off (Q1808) IC1 (QB66W) (WQ73Q) IC2 (QH43W) TR1-3 (QB73Q) TR4,5 (QL22Y) TR6,7 (WQ77J) TR8.9
2 off (QW48C) 3 off (QW19V) Miscellaneous
(QW27E) (QX018)
10,000pF ceramic 100nF 35V tantalum luF 35V tantalum 100pF ceramic 220nF 35V tantalum
1N4001 BZY88CI5V IN4148 W005 ML926 (Group 'A')
or ML927 (Group 'B') 40106BE BC548 BC337 2SA715 2SC1162
Train receiver 1 PCB or Train receiver 2 PCB
9 off (U10K) 3 off (U100K) 3 off (U4K7)
(U47K) (U1K) (M18K)
4 off (S470R)
(WX77J) (WW54J) (WW60Q) (WX56L) (WW56L)
(QL73Q) (QHI8U)
14 off (Q1.80D) (QL37S) (QR57M) (QR58N) (QW64U)
3 off (Q873Q) 2 off (QB68Y) 2 off (QR56L) 2 off (QR59P)
(GA74R) (GAZ,55)
Details of kits are given on page 25
26
DIGITAL MILES~PER" GALLON METER
* Save petrol with this easy to build device. * Discover your car's most economical cruising speed. * Large easy to read LED display.
With the price of petrol continuing on its upward spiral, any device which can offer some means of economising on fuel consumption must be a winner! This mph meter uses readily available transducers and pro-duces a continuous display of fuel consumption under all driving condi-tions. Using the meter, it is thus possible to compare the petrol used when accelerating and cruising at speed; it is also possible to find the driving conditions which yield the optimum fuel consumption. The basis of the design is two
transducers; one transducer produces a signal in response to the flow of fuel, whilst the other is connected into the speedometer drive cable and gives an output which corresponds to road speed. The meter takes these two signals and produces a continuous digital display of miles per gallon of fuel.
Circuit The signal from the speed trans-
ducer is first "cleaned up" and then used to trigger a monostable, formed by IC1c and id, which has a very short time constant. At the same time, the signal from the fuel transducer is used to clock the divider, IC6. The chosen output from the divider is then used to trigger the dual monostable, IC5, in the following manner; a positive going edge on pin 4 produces an output positive pulse of about lms duration on pin 6;
this is connected both to pin 11 of IC5 and pin 2 of IC6, triggering the second monostable on the falling edge and also resetting the divider. The same output is used as the latch signal for the display counter/driver. The two out-puts, Q2 and Qz, from the second monostable are used to reset the display counter/driwy and inhibit the scaling oscillator circuit via IC2c and IC2d.
The purpose of the oscillator formed by ICla, lb and 2c and the gated flip-flop formed by IC2a, 2b and 2d is to enable the display to be calibrated to give a true reading and provides a means of taking into account the variety of different gearing ratios between engine and road wheels and the speedo drive cable. During the counting period, set
according to the position of link 'A', this oscillator, in combination with IC3 and IC4, produces a series of pulses which are counted by IC7. By selecting a suitable link 'B', a wide variety of gear ratios may be accommodated and the unit calibrated accordingly to give an accurate reading of miles per gallon. The series of pulses counted by IC7 are then displayed at the end of the counting period by applying the latch signal. When IC6 is reset and the whole process commences again. IC7 and the associated transistors TR2, 3 and 4 provides all the necessary signals to drive an LED display.
Construction
.03MPLETE KIT
£44.95
Fuel Flow Transducer This has to be fitted into the fuel line
between the pump and the carburettor; it is not sensitive to the direction of fuel flow but it is recommended that it be positioned with the flow axis vertical to allow air bubbles to escape. It should not be mounted where it will be subjected to excessive heat (obviously!) or where ingress of water could be a problem. The connecting cable is colour coded: Red: to +5V, through a current limiting
Flow
Return
Carb
Return Block off return
Cal
lb)
Figure 2. Pipework for fuel circulation systems.
27
CC 0 CI)
il) < —J
U.
9 R6
4- 0—L_J red 56R
1 GRD 0-1 - scrn
6 GPO 0--silver
I/13 0 5 blue dot
All
red 56N 1/4 dot
R1 +12V 1
2
CIO
11111470OF
•
+5V
10k
C6 BC548 C5 lOnF
12
11
• 9
C*1 6 0 a 5
4
14 2 3
R10 4k7
+5V
IC5
6
IC4 PIN7
7
40988E
1 14 15 11
C9 C8
• * A V •-1 1-10nF lOnF
2R290k 220k - R8
10
12
- •
13 16
D1 In
1OR 4001
Cl 680nF
PEG 1
C3 -4. t C2
680nF
OV
ICI 4001BE IC2.4011BE 1C4.4068BE
uA7805UC 13
15
8
Cl
R7
IC1b C7 15k
6 4 t ylCla 7 470 0
5 9
3 -0
IC2a
97 81 71-. 15 21 716
IC2c
IC3 4520BE
3 4 5 6 11 12 13 14 10
11
IC4
3
17
12
N I MI VI int 40, es1 cOl Cflo CO 03t 03 03i CO COI
0 0 0 0 0 0 0
11
10
3
IC4 .10---•
PIN 14
1--1R18
1- 11:116
r- 11315 = R14
i -11313
i —IR12 •
12 all 10k
74C925
13 14 15 1 2 3 4
11 16 8
9 7
OV TR4
BC 141
6
TR2
TR3
BC141
16
all 22R r-CSI cc
BC 141
120 +5V
14
R20 E22OR
16 15 3 2 1 18 17 1 10 8 6 5 12 7
DISP 1
14 13
7 6 4 2 9 10
DISP 2
Figure 1. Circuit diagra m of mpg meter.
resistor (included in the main circuit). Blue: signal output. Screening: connected to ground (OV). Many modern cars have fitted some
form of continuous fuel circulation between the tank and carburettor. This is to prevent evaporation of fuel and comply with various Federal and European regulations on emission con-trol. In order to give a sensible reading, the fuel flow transducer must only have fuel passing through it which is used by the engine, and not that in continuous circulation. To achieve this it may be necessary to slightly modify the pipe-work, usually by fitting some form of bypass between "flow" and "return" and fitting the transducer in the arm taken from the "flow" side, as in Figure 2. This method may also be used on
cars fitted with fuel injection, by placing the transducer in same position relative to the metering pump, i.e. in the low pressure feed line. (CAUTION: Under no circumstances attempt to fit it in the 28
Flow transducer fitted in fuel line.
i+ Dl 2
- Al - +LA,j+ L.....1 CR 2-A C2 IC5
A-3 -
L TR, R4 11 ,„ (] -c n r,o I
C4
EL E r" 09
IC 1
B46 82 8 1
135
lI
80 13 0
1 120
R19
IC3
MAPLIN GA76H
• ISS.2 \TI mpa METER MAIN BD.
Ait ALIN
inkcitANI plc"' LoIL.--1
Figure 3. Main PCB track layout and component overlay
high pressure injector lines!) Care needs be exercised here as the feed pressure is important to ensure correct filling of the metering pump and without a constant flow through the pump, trapped air or vapour bubbles can present a problem.
Speed Transducer To fit this, remove the speedo cable
and cut the outer sheath at the point where it is intended to fit the trans-ducer; again, keep it away from heat and/or water. Make a second cut, removing 1/2" of the sheath from one of the cut ends and discard. Remove any burrs from the sheath ends. Remove any oil or grease from the inner core and replace it into the short sheath section. Place the transducer cable clamps (not included in the parts list, but use small jubilee clips or similar) on both ends of the transducer. Insert the loose end of the cable core into the single terminal end of the transducer and push through the internal friction bushing. This can be a tight fit, so take care not to kink or distort the inner cable. Tighten the clamp, but make sure the core is still free to rotate; some sheaths will require insulating tape wrapped over the end to make up the diameter to obtain a firm grip. Feed the loose cable core into the long sheath section until it also seats into the transducer and tighten the clamp carefully. Before refitting the speedo cable to the vehicle make sure the inner core does not bind in any way — there should be about 1 mm of free move-ment along the axis of the transducer. Any tightness or binding will cause excessive cable wear or oscillation of the speedo indiGator needle. This is an operation which needs to be performed with care, making sure, for example, that there will be enough room for the transducer in the position it is intended
to fit before cutting the outer sheath. Two PCBs are required. One is a
display board and ideally should be fitted into the car dashboard, the other is the main logic board which holds all the major components and may be mounted in any convenient place out of sight. It is connected to the display board by only 5 wires. Note that one of the corner fixing holes in the main board is in the PCB OV line, so that if the PCB is fixed to the car chassis the OV line will be grounded. Construct the main PCB. First insert
all links (only some of links A1-7 and B1-8 will need to be made). Next fit IC holders, resistors, diode, transistor and capacitors, taking note of polarisation. Mount REG.1 onto the PCB. Smear the mica washer both sides with Therm-path and position onto the vaned heat-sink. Bend REG.1 over onto heatsink and bolt through the PCB. Finally, fit
Veropins and ICs. Now construct the display board. Fit
all links, resistors and transistors, then fit displays noting that on the side of display 1, the 'M' in the code number relates to pin 1 and for display 2 the dot on the display is next to pin 4. Finally fit the IC holder and IC7 and
insert Veropins from the component side so they protrude from the rear for ease of wiring.
Calibration To ensure that the display gives a
true reading, it is necessary to set the links between IC3 and IC4 to give the required scaling factor. To do this accurately the speed of rotation of the speedo cable needs to be known at, say, 30 mph. Sometimes it is possible to obtain such information from the manufacturers, when it is often given as
Speed transducer fitted in speedo cable.
29
Figure 5. Calibration circuit.
17
160 0 ••••••••
1C7 1
R22
R21
R26
R27
TR3 0 18
R75 —1 =F"
R24
R23 —1 =i— R20 •-•1 =.
DISP 1 DISP 2
ii
GA7 7J
Figure 4. Display PCB track layout and component overlay
appropriate links between IC3 and IC4, each link having the following "value":
the number of turns per mile travelled. If this is not known, then the meter itself may be used to measure the required output frequency from the speed trans-ducer. To do this, omit IC6 and set link 'B' temporarily to position 'I'. The circuit shown in Figure 5 can then be used to provide pulses for IC5. Measurement of the output fre-
quency is obtained by first driving the car at a constant speed of 30 mph, indicated by the speedo; the push switch is closed and then opened at the start of a timed interval of 10 seconds. At the end of this time the switch is closed and allowed to open on the ten second mark. The display should then show the required frequency (ignoring the decimal point on the display). The value should be expected to be in the range 100 to 200Hz and it would be a good idea to take an average of several such readings. The scaling factor for the counter
circuit can then be found from the following equation using the appro-priate values:
8.5 x 3000 = n X x Y
where X is the division ratio of the 4024 divider selected, Y is the frequency obtained above and n is the scaling factor. For example, if the divider is set on '8' and the frequency at 30 mph is 140Hz, then
8.5 x 3000 = 22.76 8 x 140
This mast be rounded to the nearest whole number, in this case 23. The factor is set by connecting the 30
LINK 8 2 3 4 5 6 7 8 VALUE 2 4 8 16 32 64 128
So to set a scaling value of 23 the links number 1, 2, 3 and 5 would be made; i.e. value = 1+2+4+16 = 23. If it is chose!" to set the 4024 divider
to some ratio other than 8, then the scaling factor would need to be altered accordingly. The choice is not critical, but it should be remembered that whilst low division ratios will give a more instantaneous reading of mpg, such variations as fuel pump surges will give a fluctuating display; higher division ratios will allow more time for these variations to be averaged out, and a ratio of 8 is suggested as a starting point.
MPG METER PARTS LIST Resistors — all VW 5% carbon unless specified RI R2 R3,10 R4.5,I2-19 R6,11 R7 R8,9 R20 R21-27
Capacitors C1,2 C3 C4,7,10 C5,6,8,9
Semiconductors ICI IC2 IC3 IC4 IC5 IC6 IC7 RE 0.1 01 TRI TR2,3,4
Miscellaneous DISP.1 DISP2
lOR 3W wirewound 47k 4k7 10k 56R thW 15k 220k 220R 22R
6130nF 35V tantalum 100uF 10V axial electrolytic 470pF ceramic lOnF monocap
4001 BE 4011BE 4520BE 4068BE 4098BE 40246E 74C925 uA7805UC 1N4001 BC548 BC141
DD display type C 1/2" display type 4 Vaned heatsink Kit 'P plas Small thermpath DIL skt 14-pin OIL skt 16-pin Veropin 2141 Flow sensor Speed sensor MPG meter main PCB MPG meter display PCB
2 off 10 off 2 off
2 off
7 off
2 off
3 off 4 off
4 off 3 off 18 off
(WIOR) (M47K) (M4K7) (M10K) (556R) (M15K) (M220K) (M220R) (M22R)
(WW59P) (FE348C) (WX64U) (YY08J)
(QX018) (QX05F) (QX33L) (QX24(3) (QX29G) (QX13P) (0Y08J) (QL31J) (QL73Q) (073Q) (QI338R)
(BY68Y) (FR41 U) (FL58N) (WR23A) (HQ00A) (BL18U) (BL19V) (FL21X) (YX£36T) (YX85G) (GA76H) (GA77J)
A complete kit of parts is available Order As LW67X (MPG Meter Kit) Price £44.95 Price shown may have changed after 14/8/82.
HOME SECURITY SYSTEM Continued from Page 11
external horns will sound along with LED 2. Turn the key switch to "dis-arm" and both horns should stop sounding. Note that the 12V external batteries supply the horn only, via TR2. When not in use, the current drain from B1 and B2 is approximately 5uA and will not effect the shelf life of the batteries greatly. If the external horn is not loud enough, make R5 on the external horn PCB& R9 on the main PCB into links.
Using The System Various systems for sensing and
triggering the alarm unit are available and are listed in the parts list. Typical connections are shown in Figures 18, 19 and 20. Note that for maximum security only five switches, each with a 22k resistor, should be used per input (10 switches per module) and connected as in Figure 18(C). With 6 modules in
use, up to 60 switches can be accom-modated, using a two wire system, or 30 switches using the 4 wire system.
Wall mounted External Horn Box.
Whatever method is favoured, refer to the break contact setting up procedure and adjust RV1 and RV2 on each module for half the supply voltage. Any form of shorting, bridging, reversing or cutting connections will trigger the alarm. If one input only, per module, is to be
used, terminate the remaining input with a 22k resistor (see Figure 16) otherwise the alarm will keep sounding, with that channel switched in. Magnetic reed switches can be
mounted into door frames and the magnet into the door directly opposite. Surface type reeds are available for
External Horn has 104 dBA output at 3m
metal frame works. Pressure mats should be placed
under carpets etc ensuring adequate clearance from furniture and metal foil strip can be fitted to glass panels. There will shortly be ultra sonic and micro-wave doppler detectors available and those will interface directly to the break contact module. Finally, remember that setting the
modules to half (+2.5V) supply rail will allow detection of short circuits or open circuits, within the contact loop so make or break contacts may be accom-modated, using suitably placed 22k resistors.
Copies of issue 1 are still available, and include all these interesting projects: Universal Timer. A comprehensive programmable controller for up to 4 mains
appliances. There is storage for up to 18 program times, ons or offs and relay outputs. Complete construction details.
Combo Amplifier. Superb 120W MOSFET power amp with low-noise BI-FET pre-amp having built-in flanger, inputs for guitars, keyboards or microphones, and five step equaliser. Complete construction details.
Temperature Gauge. Coloured LED indication of 10°C to 100°C. Comple
