I'm a software guy and I'm trying to understand this line frequency meter circuit (on my way to trying to replicate a passive component only tachometer circuit):
The same circuit (different semiconductors) appears in multiple sites:
http://circuit-diagram.hqew.net/Power$2dline-frequency-meter_17270.html
http://www.next.gr/meter-counter/frequency-meter/power-line-frequency-meter-l12726.html
http://circuit-diagram.hqew.net/Power$2dfrequency-meter_16885.html
http://circuit-diagram.hqew.net/Power-line-frequency-meter_10894.html
http://www.eleccircuit.com/simple-ac-wattmeter-circuit/
If the input was DC, 110V thru 100KΩ would only be 1.1mA (and 240V would be 2.4mA), so I don't understand how 60Hz AC input would deliver 60mA to the movement!!
And if 1A = 1 Coulomb / second, and 1 Coulomb = 1 Volt * 1 Farad, I expect that capacitor charging current seen by the meter would be:
Volts * Capacitance * Hz.
For 6.8V, 0.22μF and 100Hz, this only comes to 149.6μA
What am I missing???
The same circuit (different semiconductors) appears in multiple sites:
http://circuit-diagram.hqew.net/Power$2dline-frequency-meter_17270.html
http://www.next.gr/meter-counter/frequency-meter/power-line-frequency-meter-l12726.html
http://circuit-diagram.hqew.net/Power$2dfrequency-meter_16885.html
http://circuit-diagram.hqew.net/Power-line-frequency-meter_10894.html
http://www.eleccircuit.com/simple-ac-wattmeter-circuit/
If the input was DC, 110V thru 100KΩ would only be 1.1mA (and 240V would be 2.4mA), so I don't understand how 60Hz AC input would deliver 60mA to the movement!!
And if 1A = 1 Coulomb / second, and 1 Coulomb = 1 Volt * 1 Farad, I expect that capacitor charging current seen by the meter would be:
Volts * Capacitance * Hz.
For 6.8V, 0.22μF and 100Hz, this only comes to 149.6μA
What am I missing???