Hi Guys,

wonder if you can help me? I have very basic electronic skills but need a circuit that will operate a relay every time a 12v car ignition coils sparks, the spark rate of the coil is once every 2 seconds.

Thanks in advance...

Lee

 

I have very basic electronic skills but need a circuit that will operate a relay every time a 12v car ignition coils sparks, the spark rate of the coil is once every 2 seconds.

Hi Lee,
Is it that you need to detect whether a spark is being generated, or would it be sufficient to detect whether the ignition points are opening and closing? (assuming that the coil is being triggered from points/condenser, that is.)

Also, relays are quite slow to react to current being applied or removed from their coils. It might take 40-80mS for the relays' contacts to close once the coil is energized. Additionally, relay contacts "bounce" when making or breaking; it takes a while for them to stop bouncing.

It would help a lot to know more about what you are actually trying to accomplish.

 

Hi

thanks for the fast response. What I need it for is for one of our Armoured Cars, we use an oxygen/propane system to Sim-fire the cannon, this is achieved by solenoid gas valves & an electronic board which triggers the 12v ignition coil. We have just added a pneumatic recoil system for the gun but need a way of starting the recoil as close as possible to the moment plug sparks. At the moment I am activating the pneumatic valves with latching relay board & a momentary switch but this is just for testing the system, I need a way of switching the board when the Gun fires(Sparks).
The spark rate of the coil is very slow as the gun is only fired once every 2-3 seconds.

This is the latching board I am using
http://cgi.ebay.co.uk/Latching-rela...ryZ42899QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Cheers Lee

 

Hi.
Wrap a piece of aluminium foil to a couple of inches on the wire carrying the high voltage to the spark gap.
Connect a neon bulb to that foil and ground.
Glue a phototransistor to the neon bulb. Encapsulate everything so no daylight perturbs it.

You have made a neon optocoupler, and should trigger your circuit properly.

Yes, the opening of the points can also be used to trigger your circuit.

 

OK - does the electronic trigger for the ignition coil apply a momentary ground (earth) to one side of the coil, and the other side of the coil is hooked to 12v?

 

OK - does the electronic trigger for the ignition coil apply a momentary ground (earth) to one side of the coil, and the other side of the coil is hooked to 12v?

I've attached a schematic of the system, the solenoids have a fill time of 1second & then switch off, the coil is triggered 20ms after this..

Cheers Lee

 

Well, you have a +12v trigger signal going to the coil. You could tap off of that.