Alternate tachometer output for AVC1 voltage regulator

[Sonex1517]

My GRT Mini shows an almost exact match to my TinyTach at idle on the ground. I’m using the AVC1 now, and once our insane Chicagoland weather settles down I will report back from a flight.

[Spaceman]

Robbie, you mean you're still using the alternator lead for your RPM and it seems to be working, right?

[Sonex1517]

Yes Chris. That is exactly what I mean.

[Spaceman]

Gotcha. Yeah I'm curious why B & C says the voltage regulator would cause the alternator to stop being a good RPM source to begin with... They didn't explain why that is

[T41pilot]

My GRT Mini shows an almost exact match to my TinyTach at idle on the ground. I’m using the AVC1 now, and once our insane Chicagoland weather settles down I will report back from a flight.

I'll be looking forward to your flight report on your Tach readings as well Robbie since I have that regulator installed as well.

[Sonex1517]

Brief, preliminary update. The RPM does not work with the regulator as far as I can tell.

I’m two test flights in after reinstalling the Jabiru 3300. First flight, after three minutes of good reading, the RPMs began to fluctuate and then dropped to zero.

I removed the RPM connection for the second flight (I have a TinyTach) and the regulator does not seem to be charging my battery. It did not appear to be doing so on my first test flight either.

So unfortunately at this point, I’m going back to the original voltage regulator and going to contact the manufacturer of the new one to see if I did something stupid.

[rizzz]

Brief, preliminary update. The RPM does not work with the regulator as far as I can tell.

I’m two test flights in after reinstalling the Jabiru 3300. First flight, after three minutes of good reading, the RPMs began to fluctuate and then dropped to zero.

I removed the RPM connection for the second flight (I have a TinyTach) and the regulator does not seem to be charging my battery. It did not appear to be doing so on my first test flight either.

So unfortunately at this point, I’m going back to the original voltage regulator and going to contact the manufacturer of the new one to see if I did something stupid.

I had the same problem with my Harley Davidson regulator, as soon as the battery is fully charged, the current flowing out of the regulator drops away and so does the signal to the rpm sensor.
I’m no expert but I believe this is just a difference in the design of the regulator and how it behaves when current being drawn drops away to near zero.
If you start your engine with your battery drained a bit more than usual, you’ll probably find you get a functioning rpm indicator for a little longer.

I have an ammeter in my Sonex so I was able to directly observe the correlation between current flowing out of the regulator dropping away, and rpm signal dropping away, so the cause of the problem was very clear to me.
I ended up using a different source to pick up RPM, i.e. a hall effect sensor on my magneto.

[Spaceman]

I guess that makes sense why the RPM output might not work but I wonder why it wasn't charging the battery!?