Philipp said:
Thanks (I expected it to be more complicated though).
Many of these probes have a resistor between the read-out pin and its
ground. And in case of some Tektronix scopes, they use this resistor
and scope's internal resistor to form a voltage divider to devide some
know internal reference voltage. They look at the divided voltage to
determine the type of probe connected.
Since I had nothing better to do this afternoon at work, I decided to
measure this resistance for probes around me. So the following table
was made.
Probe Series R Type Readout R
----------- -------- ------ ----------------------
TEK P6053 9M x10 INFINITY
TEK P6062B 360/9M x1/x10 INFITITY/12K
TEK P6106 9M x10 11K
TEK P6130 9M x10 11K
TEK P6131 9M x10 11K
TEK P6137 9M x10 11K
TEK P6138A 9M x10 11K
TEK P6139A 9M x10 11K
HP 10073A 900K x10 11K
HP 10441A 900K x10 obviously zero(3-1ohm)
LeCroy PP062 500 x1(?) 11K
This is why when I connect LeCroy PP062 to Tek scope, it thinks it's
a x10 probe, but actually I get ten times bigger waveform.
Then I became even more curious. So I used bunch of 1K ohm and other
resistors to "test" how Tek scopes judge probe types based on this
resistance. To my surprise, somewhat modern TDS684B distinguished 7
different probe types including x1 as default. Following table is the
result.
Readout R TDS684B 2465DMS
--------- ------- -------
11k x10 x10
10k x10 x10
9k x10 x10
8k x10 x100
7k x100 x100
6k x100 x100
5k x100 x1000
4k error x1000
3k x2 x1000
2k x5 x1000
1k x200 x1000
510 x1000 ID mark
I've never seen x2, x5, x200 or x1000 probes myself, as well as I'm not
sure if my afternoon was well spent today.
Atsunori