Measuring low AC voltages with Arduino or ESP32

J

Jordan1

New Member

• May 13, 2019

• #1

Hello.
I am looking for a way to measure AC voltage with frequency from 100 to about 25.000 Hz which is in the range from about 10 mV to about 80 mV which comes from a small coil.
Any suggestion will be appreciated.

 

P

Pommie

Well-Known Member

Most Helpful Member

• May 13, 2019

• #2

Use an opamp to amplify it. BTW, 25.000 is the same as 25 here. Do you mean 25kHz?

Mike.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• May 13, 2019

• #3

Use an opamp to amplify the signal, then an active rectifier to generate a DC voltage that represents the AC voltage - essentially you're making an AC millivoltmeter.

 

J

juam_r

New Member

• May 13, 2019

• #4

Here are some very low noise opamps: MAX4475 or LMV771. The LT1167 instrumental amplifier may be useful and simpler to configure.

 

J

Jordan1

New Member

• May 13, 2019

• #5

Great. Thank You guys. Btw. Is there some ready schematic of some of these amplifiers which I can follow in order not to mess up the things ?
Btw. seems like none of these is available around :'(

 

J

Jordan1

New Member

• May 13, 2019

• #6

Yet. even connecting these amplifiers - how would be the actual measurement occur, since the voltage is high frequency ?

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• May 13, 2019

• #7

Jordan1 said:

Yet. even connecting these amplifiers - how would be the actual measurement occur, since the voltage is high frequency ?

Click to expand...

As I said in post #3, you use an active rectifier to make it DC, exactly like an ac millivoltmeter (which is what you're building, just using an Arduino as the display) - here's one example you could utilise:

**broken link removed**