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Posted Jan 31, 2012 at 3:58 pm
Figure 1
Measuring the power drawn by electrical appliances accurately is achieved by this Enerjar project which is an easy-to-build device.
The voltage and current traveling through the mains is measured by the analog circuit. These are converted from large voltages of 120VAC and currents of 20A to small voltages that can be read by the microcontroller and then displayed on the LED display.
Any type of 5VDC power supply can be used for this device since an old 5V cell phone charger was used as the power supply in the original prototype. A low resistance shunt is used by the EnerJar to measure the current while a high-precision amplifier is used to amplify the voltage. This chip can amplify several thousands of times with almost no distortion or noise. The EnerJar can be modified to operate with 240V AC by changing the values of some resistor.
A PIC16F877A microcontroller runs the software since there are some people have programmer device which connects the computer to the microcontroller to upload programs and data. All of the signals are connected to the analog to digital converters of the PIC. The LED allows one digit at a time.
Rest of the project
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2 years ago: I was searching for such a great DIY Power Meter. Buying a power meter was the easiest way but I tried my chance to do one on my own. Construction of this DIY Power Meter is so nice and it is good looking. A bottle is enough for casing it and it has no danger. Thank you very much!
2 years ago: I want to build this DIY Power Meter project. Could you plese send me more detailed information about this DIY Power Meter? I need PCB files and in case connections. And what is the maximum reading can be taken by this DIY Power Meter?