Hello i go by trent or tbone, im a mechanic and just getting into arduino, im looking to make a simple waste spark ignition system with 3 hall sensors and 6 ignition coils to run my 1987 F350 with a straight 6, what im looking for is what transistor and how i would set it up, the hall sensors output a 5v signal when they see a magnet, but the trigger to fire the ignition coils requires a ground signal, i wont be running this engine past 4500 rpm and as for ignition timing control will have the sensors on a circular plate that can freely rotate and use vacuum advance like a normal distributor
Have a look at projects already out there , such as mega jolt - which is a cheap way of doing the whole package .
You need rpm based advance as well as load ( vacuum or throttle position) and then a means of driving a coil pack . If you don’t get that right it will run badly.
For the price of a Megajolt , it’s not worth trying to make your own IMO. Megajolt also comes with PC software to setup your advance curve , and they may already have a curve for your engine .
i will have a look
so for my application im using Coil on plug not a waste spark system, for the advance i was gonna have the ignition pickups on a rotating wheel that will advance with vacuum and retard as things slow down
Hi Tbone, I came across your post as I was thinking of posting something similar. If I understand correctly, you are looking at doing the ignition advance mechanically - i.e. a rotating wheel which effectively mimics what happens inside a conventional distributor? And presumably, if you are using just three hall sensors for six cylinders you are employing the "wasted spark" technique of firing two cylinders at once - one cylinder near TDC on the compression stroke and one near TDC on the exhaust stroke?
I think all you need is a resistor and an NPN (power) transistor between the hall sensor output and the ignition coils. The resistor into the base of the transistor, the collector to the ignition coil and the emitter to ground. It all depends on the current that flows from the coil to ground when you "ground" it through the transistor/emitter. The value of the resistor depends on the gain of the transistor and the maximum current available from the sensor. In case the current required is high it may be cheaper and more effective to use a darlington pair - cascading a low current high gain transitor and a high current, low gain one to get a result.
It's been a while since this post was active so hopefully you've worked out a solution already - please share 
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