Disturbed readings PCS10/K8047 Voltmeter

Instruments General
1

Hello,

Used PCS10/K8947 in DVM display mode and checked readings with a digital voltmeter.

Results with 3 V scale :

CH 1 - PCS10 00,00 V - Voltmeter 0,187 V
CH 2 - PCS10 00,00 V - Voltmeter 0,015 V
CH 3 - PCS10 00,11 V - Voltmeter 0,202 V
CH 4 - PCS10 00,00 V - Voltmeter 0,000 V

Furthermore, calibrated known potential difference of 1 V does not show this difference amount between connected channels.

So, what’s going on ?

Thanks…

Thanks,

2

At very low input voltages the error may be more than +/-3%.
For more details please see: viewtopic.php?f=10&t=3572

3

Thanks. Measurements being false even at 200 mV, which is 6% of 3V scale, does this means the 3V scale is not reliable at all ? I measure datas between 0 and 1V. May I amplify the signals and if yes, with what item ?

4

[quote]Measurements being false even at 200 mV, which is 6% of 3V scale, does this means the 3V scale is not reliable at all ?[/quote] On all scales you get better accuracy if you use the upper part of the scale.

[quote]May I amplify the signals and if yes, with what item ?[/quote]Yes, if you need high accuracy at very low voltage levels. You may use operational amplifier.

5

I do appreciate your quick responses.

I need to measure values between 0 mV and 1500 mV with a +/- 5 to 10 mV precision. I am not familiar with electronics at all. What kind of op. amplifier must I use and how shall I connect it to the voltmeter ? Is it a single apparatus between signal cable and voltmeter input ? Do I need 4 of them for each channel ?

Thanks again.

6

Operational amplifier is just an electronics component. You have to add some resistors and the power supply to get it working.
en.wikipedia.org/wiki/Operational_amplifier

I think you prefer a ready built amplifier module.
Using a web search I found this amplifier module:
labjack.com/support/ljtick-inamp/datasheet
labjack.com/sales

You need two of them for 4 channels and a power supply.