read engine rpm from battery/alternator???

[Steve Gorkowski]

I don't recommend this . At work we done this on engine gen. sets and regretted it
the day i started using the charger voltage . It may be done easy on cars but i had
nothing but problems Gen. sets .

Problems found:

1)Place a heavy load on Alt. the ac voltage part of the wave dives.

2) Some of the regulators use a SCR and chop the ac signal to regulate.

3) Aftermarket regulators are built different and cause problems.

Good luck

Steve

Alexander Wenning wrote:

> Recently I´ve seen that Bosch´s latest rolling road reads the engine rpm from
> the battery voltage. When connecting my multimeter to the battery I can read
> different frequencies at different rpm´s caused by the alternator. This seems to
> be easy but when connecting my 20 MHz-oscilloscope to the battery I can only see
> a flat line around 14.0 volts.
>
> Does anybody know how I can read the rpm from the battery using a
> microcontroller like PIC or Basic Stamp II?
>
> Kind regards
>
> Alex Wenning
>
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> e-mail: mail at wenning.de
>
> website: www.wenning.de
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