Wiring up Ignition Systems

Distributor Ignition

In this setup i wired up a 12v supply to the coil and it was grounded by the module. The secondary of the coil was connected to the spark plugs. the trigger was connected to the distributor. As we spun the distributor the primary circuit was grounded and ungrounded. The magnetic field collapsed across the secondary winding when the circuit was ungrounded. Spark happened at the spark plug as the circuit was ungrounded. We had to spin the distributor pretty fast to see the spark because this was a magnetic distributor and we need to turn it fast enough for it to trigger.

Coil Over Ignition

This is the coil over ignition setup. This type has a coil for each spark plug. The coil secondary is directly connected to the spark plug. We used a 5v function generator to trigger the module for the circuit to ground and unground.As we played with the function generator and speed it up, the spark came on faster.

Single Coil and function Generator

This setup is a single coil and function generator triggering the module. The module had 4 pins. A 12v supply, trigger, coil ground and battery ground. We wired it up according to my wiring diagram above. The function generator triggered the module to ground and unground. As there was 5v at the module it would let the coil ground. when the 5v was turned off,the primary winding could not ground therefore the magnetic field collapsed across the secondary winding creating a spark at the spark plugs.

Building an Ignition Module

Firstly to find the  base resistor at the base to switch on collector emitter we have to find out about our transistor.

Maximum current at base is ! amp.

The function generator will give 5v.

we will also minus the voltage drop across the base and emitter.

5v - 0.7v - 4.3v.

R = V / I therefore 4.3v / 1amp = 4.3 ohms.

Then we would calculate the resistor R3.

power supply 12v - voltage drop at vce of 0.5v = 11.5v

resistance in ignition coil 3.8 ohms.

12v / 3.8 ohms =  3.16amps

11.5v / 3.16amps = 3.63 ohms.

I used a 4 ohm resistor.

When the function generator gives 5v to the base the primary winding is then grounded through the collector an emitter. When the 5v signal at base is taken away, the magnetic field collapses across the winding into the secondary winding and creats a spark at the spark plug.