TRANSISTOR DRIVER FOR IGNITION COILS |
The principal problem with the ignition coil is the absence of a feedback coil and the big reverse EMP when the power transistor is shut off. The solution is to use a driver signal from a chip or a RC oscillator and a big Vrce transistor (some from the horisontal deflection stage in TVs are very good). |
![]() |
T1 : BD238 (pnp transistor) mounted on a small heatsink T2 : power npn transistor : BUX82, or BU526, or BU204, or BU208A mounted on a big heatsink. With BU transistors the PL150Z diodes are not necessary. The setup works well with BUs, but I had best results using a IRF260 or a BUP307 (IGBT). You can add a fan to cool the heatsink. R1 : 100 ohms @ 1 watt R2 : 330 ohms @ 1 watt C1 : 100 nF @ 1000 V polipropilene. The sparks are stronger if the RC constant is bigger, for C1 values of 1-10 uF (just experiment a bit). D1 : 1N4001. I used 1N4007. The setup works even without the diode. R3 : 2.7 kohms @ 1 watt R4 : 43 ohms @ 10 watts D2, D3 : Zenner diodes PL150 Z (they are not necessary if use a big Vrce transistor from BUs family). C2 : 200 nF @ 1600 V polipropilene Input voltage : 12- 30 VDC full wave rectifyed. Don't go above 45 VDC, or your T2 will be gone. The setup can be used as an electronic ignition in cars, with the platins connected between R2 and ground. |
Sorry for the mess, but I was just currious if the setup does work. |
RESULTS: 1-2 cm sparks (only 20-30 V input -:( ), but nice corona spray in the dark. |
![]() |