# Arduino controlled motor kill switch

I have a small honda clone engine, and I'm wondering how it is I can rig the arduino up to its kill switch. From what I understand (which admittedly is not much) the kill switch only shorts out the magneto in the flywheel to the metal case I have no idea what sort of voltages/amperage I would be dealing with, so I don't know if a small transistor would be sufficient, or if a relay is needed Once again, all help is appreciated! Thanks!

I have no idea what sort of voltages/amperage I would be dealing with

I suggest you find out with a basic multimeter

From the secondary, several thousand volts but low amps (probably a few hundred mA, if that). The primary will likely be low voltage, with slightly higher amperage.

Both will be outputting pulsed DC, and you won't be able to measure the output easily with a multimeter (whatever you measure will likely be a "ballpark average"). What you really want to use is an oscilloscope (at least to know the voltage; regardless of the primary or secondary, the output current is likely small - call it an amp or two). If you are intending on measuring the secondary, you will need a high-voltage probe for the scope (most scopes only go up to a few hundred volts or so of range). The purpose of using a scope to measure the voltage is so you can see the series of voltage pulses over the time-period you have the scope set for; in other words you can see the tops of the peaks, and know the actual "peak voltage" vs the average you would get on a multi-meter between the peaks and the valleys.

Osgeld:

I have no idea what sort of voltages/amperage I would be dealing with

I suggest you find out with a basic multimeter

I have previously tried to find a voltage with a multimeter (primary to case) but I was getting around 1 volt or so. I wasn’t sure if that was a reading or just interference
Unfortunately I don’t own an oscilloscope, so no dice there :
I will see if I can do a little more work with the multimeter to find some info
Although from what I’ve read, assuming the current is low (<500ma) and the voltage on the first stage is low (I would assume it to be so) I should be able to use a transistor (like a 2n2222) in place of the switch, right?