Infrared emitter and detector pair

Yup. Lookup Rogowski coils.

Or spiral.

--Winston

It means that it's green and putrid-tasting. You have to add balsamic vinegar to cut the taste, and then put it over bad-tasting 'baby greens' to make a modern salad. Ain't progress wonderful. :(

Cheers

Phil "plain lettuce forever" Hobbs

in" means

er.

not

Oh, Honeymoon salad?

"Lettuce alone, undressed."

George H.

t- Hide quoted text -

means

:)

Cheers

Phil Hobbs

I like my salad like I like my women - not dressed. ;-)

Cheers! Rich

I think John was picturing your descritionj being a coil wound round the plug lead. I can see a way to wrap a coil round a plug lead and achieve magnetic coupling, it'd be wrapped in such a way as to form a toroid shape.

Yes, this is how most automotive tachometers work.

anoter way to do it would be to sense the leaking magneic field of the spark coil.

or to put a coil in a magnetic field near the ring gear on the flywheel (or tap the one that's already present in many vehicles)

Several turns of wire around a spark plug wire will work just fine for tachometer purposes. With a simple limiter you can read the RPM directly using a sound card. See "Engine RPM Measurement" at .

Best regards,

Bob Masta DAQARTA v6.00 Data AcQuisition And Real-Time Analysis

Both these statements are right. A 'coil of wire around it' doesn't achieve current sensing unless your winding is not a simple wraparound, because it's parallel windings that have flux coupling. The wire-around sensor is a capacitive (voltage spike) sense transducer, not a current transducer.