Talk:Test probe

x1/x10 probes - why?

Lots of passive scope probes have a x1/x10 switch. In all my years of engineering work, I have never switched one of these probes to x1. The only reason I can think of for having this switch is in case your scope doesn't have a x10 probe setting, but then I've never seen such a scope. Is there any technical reason why you would ever want to use a probe in x1 mode? --Heron 16:14, 26 July 2006 (UTC)

I never have either. As for the scope, I thought that's what the extra pin was that makes contact when you connect the scope (the gold ring around the socket) - if you insulate that, the scope doesn't know it is a 10x scope. My only hypothesis is extremely low voltage signals - but then you don't use a standard probe. For example, when I had to do some super low voltage at 1x, I used a cable that went from SMA right to the scope... — RevRagnarok ^{Talk Contrib} 16:49, 26 July 2006 (UTC)

When all the gain you had was 50 mV/division and you were trying to look at low-level signals, you bet you switched your probe to 1X! ;-) It's a lot less of an issue nowadays where ranges such as 1, 2, or 5 mV/division are common.

By the way, on most Tek scopes, "that ring" isn't just binary. Certain values of resistors between BNC ground and that ring will also cue a 100x attenuation factor. Nowadays, of course, TekProbe and whatever they call the newest probe interface have far more capability, with the 'scopes routinely displaying things like probe model numbers and serial numbers.

Atlant 18:04, 26 July 2006 (UTC)

1x is used for low level measurements like power supply ripple measurement. --Faixu (talk) 09:16, 2 June 2010 (UTC)

Z₀ probes

Heron just switched the Z₀ discussion into the present tense and, while I'm sure these probes are still used and I agree with those edits, they lead me to wonder: Are new Z₀ probes still being sold by anyone? They're certainly obsolete; I was looking at the specs on one of our FET probes and in every area except dynamic range, it blows the Z₀ probes away:

Tek P7240:

• <120 ps t_r
• 4.0 GHz bandwidth
• 0.85 pF
• 20 KΩ
• +/- 2V dynamic range and
• +/- 5V dc offset, so
• +/- 7V working range
• 30 V peak absolute max

Again, except for the price (probably) and the fact that the Z₀ could withstand ac signals of about 15 volts RMS or so, the FET probe wins hands down. And the particular one I cited is wonderfully miniaturized with an integrated ground foot.

Atlant 12:29, 8 December 2006 (UTC)

I just cleaned up the Z₀ section. Z₀ probes are certainly not obsolete and still sold (Agilent 54006A, Lecroy PP066 and Tektronix P6150). Advantages include bandwidth (Tek P6150 is 9GHz in 10x mode) and input capacitance (<0.15pF for Tek P6150). At high frequencies, the impedance of the parasitic capacitance is much more significant than the resistance. The other advantage is that the impedance doesn't change much over the bandwidth (500 ohm at DC to ~100 ohm at 9GHz, as opposed to 20 kohm at DC to ~50 ohm at 4GHz for the P7240). Other advantages are listed here and here.

Faixu (talk) 09:16, 2 June 2010 (UTC)

Passive probes

In this extract:

"At low frequencies (where the resistance of R is much less than the reactance of C), the
circuit looks like a resistive divider; at high frequencies (resistance much greater than
reactance), the circuit looks like a capacitive divider.[1]"

I think at low frequencies the resistance is dominant, thus it looks like a resistive divider, and at high frequencies the reactance is dominant, thus it looks like a capacitive divider.

I have not made the edit because I may be wrong and would like others to confirm. — Preceding unsigned comment added by 118.209.58.71 (talk) 10:02, 13 July 2014 (UTC)

Sperate source test on Transformer

Why the voltage difference in a high voltage transformer with measurement of high voltage side through a capacitive divider and low voltage side with a multi meter — Preceding unsigned comment added by 180.211.96.58 (talk) 07:13, 11 December 2015 (UTC)