probe in a robe Re: [sdiy] I have seen the light (litteraly)

[Ingo Debus]

Am Sonntag, 23.01.05 um 01:22 Uhr schrieb anthony:

> So the probe I made out of a broken soldering iron handle, a DMM probe 
> with a 1Mohm resister and a 30 pf trimmer cap with some wire and a 
> clip thrown in is OK? Cuz I made it and never used it (and I wonder if 
> I can find it) because I figured if that crap would work then just 
> some wire and RCA adapters work.

Hm, the typical 10x scope probe has a 9 Megohms resistor in it, not 1 
Megohm. In series with the usual 1 Megohm input resistance of a scope 
this will give you 10 Megohms.
DIYed or commercial, such a probe has a much better performance than a 
wire-only "probe". The trimmer cap compensates for the capacitance of 
the cable. Is there a test generator (rectangle) in your scope? Use it 
to calibrate the trimmer such that the scope shows a true rectangle.

I once tried to DIY a scope probe. It was so flimsy that I immediately 
went out and bought a probe ;-)

Ingo