This is Electronic Siren circuit diagram. The sound produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors are off. When the push button switch is pressed to 10u capacitor will charge via the 22k resistor. This voltage is applied to the base of the BC108B which will turn on slowly. When the switch is released the [...]
This is LED flashing circuit, the circuit is quite simple. Alternatively, you could be create another shape, not just heart shape. Schematic diagram: Component list: Resistors R1, R2 - 470 ohm, 1/2-watt R3-R5 - 100 ohm, 3-watt R6-R8 - 1000 ohm, 1.4-watt R9 - 5000 ohm potentiometer Capacitors C1, C2 - 100uF, 16 volts, electrolytic radial Semiconductors IC1 - 4047, low power monostable/astable multivibrator Q1-Q3 - 2n3643 NPN transistor or [...]
