Checking if a tach works?

[Alan.UK]

Hi,

Is there are way of checking if a tach works when it is out of the car?

Thanks in advance

Alan

[POKDUB]

If you had access to a frequency generator device. This would normally be a device found in a tech college lab, maybe there is one close by, I am sure they wouldnt mind testing it for you.

I had to rebuild my tacho as the circuit was duff. I didnot mind as I have electronics background.

BTW, coincidence, I just bid on your seat belts.

[Alan.UK]

Thanks Peter.

It looks like I may be off to the local uni and ask them in the labs. I am sure they will not mind as I was there myself for 5 years.

Thanks

Alan

[POKDUB]

This table might help when you get there.

Frequency generator calibration ;

4 stroke engines fire every 2 revolutions of the crankshaft, so the conversion from RPM to Hz is divide the number of cyl by two then multiply that result times the desired RPM to get firings per minute and divide by 60 to get firings per second.

Frequency in Hertz (cycles per second)
RPM 8cyl 6cyl 4cyl
1000 66.7 50 33.3
2000 133 100 66.7
3000 200 150 100
4000 267 200 133
5000 333 250 167
6000 400 300 200
7000 467 350 233
8000 533 400 267

[Alan.UK]

That's great, cheers Peter