# How to measure AC level of 100 KHz

#### Wendy

Joined Mar 24, 2008
21,914
Most DVMs are rated 40-400 Hz, Any suggestions beside an oscope how to measure this frequency?

Joined Jan 15, 2015
4,749
You can look for an RF Voltmeter or would a scope work? If you have a clean sine wave I would use a scope and look at the peak to peak and do the math. As to an actual RF Voltmeter names like HP and Boonton come to mind.

Ron

#### SLK001

Joined Nov 29, 2011
1,541
A diode and a cap will give you the peak voltage. If a sine wave, multiply by 0.707 to get RMS.

#### Wendy

Joined Mar 24, 2008
21,914
I was thinking about a precision diode. With a Hi freq op amp I'll post the circuit later anyone know of a AC voltmeter that goes into the ultrasonic range?

#### strantor

Joined Oct 3, 2010
5,178
Would an old school analog VOM work?
I don't see why an analog meter movement would care about frequency.
Simpson 260 datasheet doesn't give any frequency stipulation for voltage measurement.

EDIT: actually in the owners manual it gives frequency info:

#### Wuerstchenhund

Joined Aug 31, 2017
187
Most DVMs are rated 40-400 Hz, Any suggestions beside an oscope how to measure this frequency?
What voltage levels are we talking about? And what precision/resolution do you need?

In general, a DMM like the Keysight U1252B which is spec'd for frequencies up to 100kHz in some of its voltage ranges can be used, although there will be a certain amount of error. A RF voltmeter could be another option, provided its frequency range goes down to 100kHz.

But I still think a good DSO (set to average/HiRes/ERES) is probably the best way to measure the AC voltage. Especially if the signal isn't a sine wave.

#### Wendy

Joined Mar 24, 2008
21,914
I have an oscope I won' to able to access for years (most likely) due to my stroke. I'm thinking in terms of a low budget hobbyist bench. this idea started with this,
How to measure an inductance

#### OBW0549

Joined Mar 2, 2015
3,105
I have an oscope I won' to able to access for years (most likely) due to my stroke. I'm thinking in terms of a low budget hobbyist bench.
There's low budget, and then there's LOW budget. Not sure which you're referring to.

#### MrAl

Joined Jun 17, 2014
6,833
Analog Devices makes something very similar in an 8 pin DIP, the AD737 (Also what looks like an 8 pin SO). They were about \$4 each in small quantity. The performance does not approach that of the Linear Technology offerings but it was just fine for audio device R&D.
Hi,

One of the things i liked about the previous chip (LT device) you found was that it goes up to 100kHz and beyond. I think that is a big plus for measuring AC signals which might be 100kHz or a little above.
20kHz wouldnt be too bad i guess.

#### DickCappels

Joined Aug 21, 2008
6,014
At the risk of going too far off topic, the LT chip has 1% additional error gain at 500 kHz.

#### bertus

Joined Apr 5, 2008
20,189

#### Wendy

Joined Mar 24, 2008
21,914
I would aim for schottkey diodes myself

#### DickCappels

Joined Aug 21, 2008
6,014
I think the best approach would be dependent on the amplitude range that needs to be measured and the desired accuracy.