VM205 beginner question (probes)


#1

Hi, me again (sorry!). So I’ve happily got a VM205 working on my Raspberry Pi 2, I can connect the analog and ground wires to a simple function generator and see a meaningful result (square, saw, sine etc) - all good.

But it’s a little noisy sometimes, so ideally I’d like to move away from using raw patch wire and use a probe instead. Can I just buy a simple ‘Universal 100MHz Oscilloscope Scope Probe’ type kit, and then wire up a BNC socket to the AI1 and GND pins on the VM205 board?

I’m a complete noob with this, sorry - I’m just fascinated with it and would love to get the most out of it.

On an additional note, see my new post about the software…


#2

[quote]Can I just buy a simple ‘Universal 100MHz Oscilloscope Scope Probe’ type kit, and then wire up a BNC socket to the AI1 and GND pins on the VM205 board?[/quote]Yes, you can do this but there are some problems using a standard oscilloscope probe.
The oscilloscope probes are designed and calibrated for use on oscilloscopes that has an input impedance of 1 MΩ.
The input impedance of the VM205 is 100 kΩ.
So you can use only attenuation ratio setting x1 of the probe but not x10.

radio-electronics.com/info/t … probes.php


#3

[quote=“VEL255”]Yes, you can do this but there are some problems using a standard oscilloscope probe.
The oscilloscope probes are designed and calibrated for use on oscilloscopes that has an input impedance of 1 MΩ.
The input impedance of the VM205 is 100 kΩ.
So you can use only attenuation ratio setting x1 of the probe but not x10.
[/quote]

Understood - thank you, that’s fine. And thanks for the quick reply. :slight_smile: