Simple AC wattmeter circuit
Power line frequency meter
This is the meter show the frequency of a power generator, which it has voltage 110V-240V at 10-100HZ.
The output sine waves are converted to square waves by the 100k 2 watt resistor and the 6.8V 1watt (1N3829A) zener diode.
Then the square wave is transformed by the 0.22uF capacitor and the current is averaged by the 1N4148 diodes.
The average current is proportional directly to the frequency, so can read on a 100mA amp meter (M1).
To calibrate, book the circuit up to a 60Hz. Power line and adjust the VR1 5K pot to read 60mA.
Simple led watt monitor
This circuit is the principle of divided voltage. And current divided. Before you take the LED display up to 80 Watt. Operation of the circuit when current is flowing into the resistance. It will divide the voltage to suit each watt range. It has a resistance of 100 ohms to reduce the flow before LED. While the LED display will light sort indefinitely. Depending on the number of watts. For example, a 10-watt LED1, LED2, LED3 will light all. Try to see if the observation that even high-watt. Resistance to Divided voltage is more costly too. That is, resistors R1, R4, R7, R9, R11 and R13 determines the area to the circuit watt.
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