Re: signal leads that pick up less ambient noise?

On 19/02/2025 23:42, Christopher Howard wrote:

Martin Brown <'''newspam'''@nonad.co.uk> writes:
 

What sort of noise and at what sorts of frequency?

 Looking at in on the scope, the noise is thick, like a solid bar of
spikes around the real signal. When I zoom in on it, it seems like it
has a beat of around 40 Khz.

That could be magnetic coupled from a nearby switched mode PSU.
Does it look like a PWM square wave or a sine wave?
I only ever see ripple if I stick my finger on an probe and my environment is really rather electrically noisy.
You haven't got one of those ultrasonic humidifiers nearby?
What happens if you put a 0.1uF capacitor in series with the coax shield coax so that there can be no DC current flow on the earth connection?
--
Martin Brown