Project 11: Running light with 3 LEDs
Make 3 LEDs without control light up successively
Required parts: 9V battery*, 3x1Kresistor (brown black red gold), 3x100K resistor (brown black yellow gold), 3 x red LED, 3x BC547 transistor, 3x10|jF electrolytic capaci-tor, 2x wirejumper
This circuit makes each LED light up shortly in succession. The circuit consists of 3 identical channels. It is theoretically possible to expand: per LED a similar circuit is needed in séries with the previous. The capacitor of the next channel is charged when the transistor of the previous channel is not conducting. As long as a certain transistor is not conducting, the relevant LED will light up. Capacitor C4 is added to the circuit to create a certain starting condi-
Time to experiment: What happens when you change the value of R1, R2 and R3 to 10k?