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http://www.futurekit.com FUTURE KIT FUTURE KIT HIGH QUALITY ELECTRONIC KITS HIGH QUALITY ELECTRONIC KIT SET FOR HOBBY & EDUCATION R ǧ¨Ã¾‡Ç§àÊÕ§¡ÃÔè§â·ÃÈѾ·‹ TELEPHONE EXTENSION RINGING CODE 304 LEVEL 1 NO.2 Figure 2. Circuit Assembling Figure 1. The Telephone Extension Ringing Circuit NOTE: FUTURE BOX FB03 is suitable for this kit. TRIMMER POTENTIOMETER HORIZONTAL VERTICAL VR ..... KΩ 1 2 3 VR VR VR VR Figure 3. Installing the components RESISTOR ELECTROLYTIC CAPACITOR Watch the polarity! C + + C .....µF R R .....Ω R C + C C .....µF C CERAMIC CAPACITOR D K A D K A DIODE D K A TRANSISTOR TR NPN B E C TR PNP B E C 1 IC IC Watch the position of the notch! 10K + TEL IN + TELEPHONE WALL TELEPHONE VR + + + + + F U T U R E K I T SP 6-9V + - FK304
