High-Voltage Sensor

Charos

I need to build a sensor that goes high when a spark on a lawn mower engine fires. This will be interfaced with a BASIC Stamp from the kit Radio Shack sells.

Only the timing is important, I don't need to measure the actual voltage.

However, the voltage is somewhere between 10,000 and 20,000 volts.

I believe an inductance coil wrapped around the spark plug wire and an opto-isolator to do the interface.

Does anyone know how many turns of wire needs to be around the spark plug wire. How to prototype and test?

Is there a better way?

Thanks!

- Bill

PJAllen

I think any AM radio, especially if tuned to a spot where there is no station broadcasting,·would give an excellent result.

Post Edit -- The sparking will result impulse noise (static) which the radio will give evidence of, and it won't require any interface to high-voltages, coil winding, etc.

Post Edited (PJ Allen) : 7/21/2008 2:45:56 AM GMT

Charos

You might notice the goal is to interface the signal with the BASIC Spark CPU.

PJAllen

So what's your point?

Post Edit -- The interface would basically·be a patch cord from the radio's earphone jack to the Stamp.

Post Edited (PJ Allen) : 7/21/2008 2:52:09 AM GMT

Charos

Is there a circuit that would not require an AM radio? I use mine to listen to music made by my TRS-80....

whicker

couldn't you just paint a mark on the flywheel, or shaft, and use an optical sensor to see it?

The other thing, is that there are premade current transformers you could just purchase.