Energy Meter using VFC

[erikl]

... what i need to construct now is actually a frequency counter? Which means i get the output of VFC (is a pulse with frequency 10-10kHz) and display it with a frequency counter is it? Just want to double confirm is my idea correct?

Sure! The 4521N chip in the left bottom corner of the above schematic creates the time base for the power measurement (various time units accessible thru Q18 .. Q24, s. the 4521 data sheet). For energy measurement disable the time base unit and simply count up (until overflow ;-) ).

 

[Einar M]

I made an ampere-hour meter two years ago. I used an integrator that was reset a fixed amount when ever it reached a certain voltage. This ' reset ' pulse toggled a counter ; 16 bits to make the integration cap a resonable size. By scaling everything correctly I could read Ahrs from the top four bits. This method is easily adapted to Whr.

 

[syee10]

Einar M,

Can you explain more about your circuit? how to adapted your Ah meter to Wh meter?

 

[syee10]

Mr erikl,

Please reply me personal message =)

 

[Einar M]

**broken link removed**I have been busy with other things for a while, but was able to design and test a circuit last week. I remembered seeing a simple watt meter published by Robert Pease several years ago ( may 13 2002 ) and added a VFC similar to the LM331 but using an auto-zero Op-Amp and a CMOS 555 instead. A 74C926 and a LCD display provide four digits of watt-hours. I'm not sure the image will appear; if not go to Photobucket/Einarscircuits and look for it there.

 

[Einar M]

Here is the link again:**broken link removed**