rms to dc converter circuit

[neelam29]

hi
i want to make a true rms to dc converter for a voltmeter in which the input voltage can be any type of signal like triangular,square or sawtooth etc..and the output should be a dc voltage. please help me out to make it work.

also i cant use any costly ics like max536 or lt1966 etc.becuase of cost factor
thanks

 

[Nigel Goodwin]

hi
i want to make a true rms to dc converter for a voltmeter in which the input voltage can be any type of signal like triangular,square or sawtooth etc..and the output should be a dc voltage. please help me out to make it work.

also i cant use any costly ics like max536 or lt1966 etc.becuase of cost factor
thanks

The cost factor will be more if you don't use them, and take a lot of board space - it's a complicated thing to do!.

 

[Paul Obrien]

ther is an old ic the LH0091, I haven't seen a price on one though the LT1966 does look similar. The other way is to get two thermistors attach one to a resistor and leave the other in free air. The difference in resistance will due to the thermistor heating up as RMS is the "working" voltage ie 20VRMS sine is the same as 20VRMS square. Maybe configure the thermistors in a wheatsone bridge config. Well you did ask.