ACV measurement ( dB ) for frequenties between 2500 and 3150 Hz


I want measure AC Voltage (0 to 736 mV or 0 to 150 mV is also OK ) with a frequency of 2500 up to 3150 HZ. Do you have a module for this ?
With thanks

Hi Guy,

Short answer. No.

Long answer. Sort of.
We have a PAC module that has the right back end, we would just need to change the input components.
How many modules do you need? Is it a one off project, or is there an ongoing quantity?
The frequency is not an issue, its just the low voltage that you require… On that note, you mention 0 to 736mV, how does your AC waveform appear at this voltage?? Sounds like it has a DC offset of around 368mV???
If this is correct, this adds another level of difficulty to the module front end… Most AC voltages swing either side of 0v as you know.


Hi Ben,

I have more than 30 independent isolated inputs needed.
The measurement is at the level of a sound signal, to determine whether it is sufficiently strong presence.
0 dB (775 mV) is ok and-40dB (7.7 mV) is ok and more than 0 dB is not ok.
A second measure to prove whether any permanent voltage (mV …) is present or not.
I have the Snap AIVRMS 0-250V AV / DC, but it is not accurate enough between 0 and 1 V.
Can you make a proposal. The AIVRMS (i) has only two inputs, so for 30 inputs, about 15 modules are required?

I have up to 30 independent isolated inputs needed to dB sound signals to measure voltages from 0 to 775 mV.
I did a test with AIVRMS module 0-250V, but this is not accurate enough in the area from 0 to 1 V. This module has two inputs, so I have 15 modules, which you could possibly adapt for this purpose.
Thanks for your quick response.

Since you are talking about audio frequencies, have you considered running a small audio transformer in reverse?
This might step up the signal enough to drive the module hard enough to give you the reading your looking for.
They are only a few dollars each and so you could get one to test very cheaply. It would not take long to hook it up either…

Anyone else got any ideas?


Maybe a voltage divider to bring the signal down to AIMV-4 levels. Or can try to terminate the signals with the appropriate impedence and add a shunt to convert measurement to current and use an AIMA. The eight channel AIMA would save you quite a bit on modules.

With your situation, I think you would be better off with some signal transducers such as this one:

Then interface to Opto22 with an 2,4,8 or 32 channel analog I/O module.