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ContinuousWave: Small Boat Electrical
Tachometer Frequency Calibration: E-TEC 75-HP
|Author||Topic: Tachometer Frequency Calibration: E-TEC 75-HP|
posted 01-26-2008 01:25 PM ET (US)
I have a 75-HP E-TEC. I am putting in the boat [a SystemCheck Tachometer]. [What is the proper setting of the tachometer frequency calibration setting?] Number 5 or number 6 on the [SystemCheck Tachometer] ? Or 10 or 12 pole?
posted 01-26-2008 02:00 PM ET (US)
posted 01-26-2008 06:51 PM ET (US)
Thanks for the 6.
posted 01-27-2008 04:19 PM ET (US)
Tachometer frequency calibration adjustments are matched to the number of poles in the alternator, and this is not directly related to the number of cylinders in the engine.
The tachometer pulse output is usually derived from a half-wave rectifier tap in the engine battery charging circuit. For more information, see:
posted 04-30-2009 03:55 AM ET (US)
Have you had your device calibrated at a UKAS accredited lab for example http://www.lambda-cal.co.uk?
posted 04-30-2009 08:38 AM ET (US)
Since my boat is in North America, it would be difficult to transport to the U.K. for calibration of its tachometer.
Assuming that I had a frequency generator with known accuracy, I ought to be able to calibrate the tachometer using these principles:
Assume a motor is turning at 1,000-RPM and has a 6-pole alternator. The tachometer circuit will generate
6 pulses/1-rev x 1000-rev/1-min x 1-mi/60-sec = 100 pulses/sec, or
1,000-RPM = 100-Hz
and in a similar manner
2,000-RPM = 200-Hz
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