Tach testing

[RHB]

Any one ever bench tested an OMC tach. How do I simulate output of motor ie pulse height and frequency. Does 1000 HZ equate to 1000RPM?

 

[petryshyn]

Re: Tach testing

I believe 1000rpm = 100Hz with a 12 pole stator<br /><br />1000rpm X 6 pulses(per rev.)= 6000 pulses per minute/60seconds = 100Hz<br /><br />*if you're thinking of calibrating it to 60Hz, it may be badly skewed in the higher ranges.....

 

[RHB]

Re: Tach testing

Thanks for the info. Will pulse amplitude effect RPM indication?

 

[petryshyn]

Re: Tach testing

only if its below the triggers threshhold.....it'll get intermitent at that point.

 

[RHB]

Re: Tach testing

The tach I tested on bench responds as you stated ie 100Hz = 1000RPM etc. I set pulse height above 9V. The selector is set to 6 (cylenders I assume). The tach respond OK <br />until 3000RPM. Any readings above that RPM are very inaccurate. Any suggestions on how to calibrate the tach.

 

[petryshyn]

Re: Tach testing

Are you using an a/c sine wave or a D/C pulse?<br />How are you connecting the signal leads in respect to tach +,-?

 

[RHB]

Re: Tach testing

I used DC pulse mode, square wave with modified duty cycle (400us pulse width). I guessed pulses were positive with respect to ground.

 

[petryshyn]

Re: Tach testing

since the actual input is an a/c signal, try using 50% duty cycle. Also try using the tach power positive as common for the signal.....