Engine Speed Sensing from Alternator

[santorta]

Hi,

I would like to know how to sense the engine speed from the Alternator current or voltage?

Thnks,

Santo

 

[zeusfaber]

Neither voltage not current is particularly closely related to engine speed (the regulator is there to ensure that they aren't).

If you're lucky, you might be able to detect the ripple on the output voltage. Turn that into a train of fixed energy pulses, and you'll have a device whose output power is directly proportional to engine speed.

A.

 

[Comcokid]

Sensing engine RPM from the alternator of a engine is done on many older outboard motors and in some diesel engine applications. The signal is picked up from the alternator before the rectifiers and regulation. The signal is a sine-wave with the frequency of the signal varing with the RPM. The relationship between RPM and the frequency of the signal is determined by the number of poles in the alternator and the pulley ratio (or gear ratio). When a belt is involved, the RPM may not be exact due to belt wear and slippage.

I have not searched, but there is probably more information on-line available from companies who make tachometers - Datcon, Teleflex, VDO, Stewart-Warner, Faria, etc.

This is more detail that what was previously posted in thread67-80211