<VV> Tachometer Test Signal

[Gary Mierzwa]

Another viewpoint on tachometer test signals. Does this help?
 
Given:
 
- RPM = Revolutions per minute
- Hz = Hertz, or cycles per second (cps)
- a.c. source = Sine wave, alternating current/voltage. Common  residential power in the USA is 60 Hz
- Half-Wave Rectification = 1 pulse per Hz, only the positive half of the a.c. source makes output pulses
- Full-Wave Rectification = 2 pulses per Hz, both positive and negative halves of the a.c. source makes pulses  
- Hz x 60 = cycles per minute
- Standard, 6-cylinder, 4-stroke cycle, internal combustion, engine produces 3 ignition pulses per revolution
 
Then:
 
For a Half-Wave rectified a.c. source
60 Hz x 1 pulse per Hz x 60 seconds = 3600 pulses per minute
3600 pulses per minute divided by 3 pulses per revolution = 1200 RPM
 
For a Full-Wave rectified a.c. source
60 Hz x 2 pulses per Hz x 60 seconds = 7200 pulses per minute
7200 pulses per minute divided by 3 pulses per revolution = 2400 RPM
 
Gary Mierzwa
WFCC
Chapter 325
 
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