How does a Strobe Gun work?

[Futterama]

Hi folks,

I would like to know how the pickup on a strobe gun works.

Strobe gun = a device you use when setting the ignition timing on (old?) car engines. You place a pickup on the wire to the spark plug, and the strobe flashes everytime a spark is fired.

I would like to know how the pickup can sense the high voltage going through the sparkplug wire - if possible, I would like to make my own.

I hope someone can help.

Thanks.


Regards,
Futterama

 

[crutschow]

It likely picks up a signal from the capacitance between the wire and the pickup. It doesn't take much capacitance to get a useable signal from the high voltage spark.

If you experiment with coupling this signal into a circuit, be sure you limit the signal amplitude with zener diodes to avoid zapping the circuit.

 

[Futterama]

It likely picks up a signal from the capacitance between the wire and the pickup. It doesn't take much capacitance to get a useable signal from the high voltage spark.

If you experiment with coupling this signal into a circuit, be sure you limit the signal amplitude with zener diodes to avoid zapping the circuit.

The strobe gun is connected to the common ground (the car battery negative terminal).

How is capacitance picked up from the sparkplug wire? I have no idea how this is done. A simple schematic would be great if you have one.

 

[Nigel Goodwin]

Simply with a wire wrapped around the HT lead, or (more professionally) a spring clip (such as a clothes peg) with a metal plate on one side.

 

[Futterama]

Simply with a wire wrapped around the HT lead, or (more professionally) a spring clip (such as a clothes peg) with a metal plate on one side.

The spring clip idea sounds easy. So a metal plate pressed against the wire will do.

How do I then measure the capacitance so I can get a signal into a PIC? Do I need some kind of capacitance sensor chip? Or will there be generated a voltage on the plate with respect to ground?

 

[Boncuk]

Strobe gun

you should read carefully what is said in a reply.

Crutschow suggested you should limit the signal using a zener diode in order not to zap your circuit.

Even a layman would think that there is voltage involved.

RTFA!

Boncuk

 

[Futterama]

you should read carefully what is said in a reply.

Crutschow suggested you should limit the signal using a zener diode in order not to zap your circuit.

Even a layman would think that there is voltage involved.

RTFA!

Boncuk

Sorry, but crutschow did not mention how this signal was picked up.

Also, please don't talk down to me because you know more of this stuff than I do.