O-scope question for you old EE's

[Magnus Danielson]

>>>>> "MZ" == Merlin Zener <merlin at ion.com.au> writes:

Hi!

 MZ> Magnus Danielson wrote:
 >> 
 >> [...snip]
 >> If a scope also has a I/V figure
 >> tracker (easilly built) you have a even more powerfull tool. An I/V
 >> tracker is a very easy way of comparing a point between a working and
 >> a failing board, you may see broken inputs due to ESD etc. However,
 >> few scopes come with this property (the I/V). Few scopes lack XY mode
 >> thought (I have one which is nothing but XY, it does not even have
 >> variable input sensitivity).

 MZ> Good point. I used to have an old cro with one of those,
 MZ> now I've got one of those new fangled Tektronics digital
 MZ> ones. It's got a lot of useful functions (voltage & freq
 MZ> measurements on the screen etc) but that's one thing it
 MZ> doesn't have. You wouldn't happen to have a circuit to
 MZ> build the external version, would you?

Not yeat. I intend to dream one up, and that should not be very hard.

It is basically just a matter of

1) Generate a waveform
2) Feed the waveform throught a resistor
3) Differentially measure the voltage over the resistor to get the I part
4) Measure the voltage over the applied position to get the V part
5) Connect this up to a component.

The basics is not at all very difficult, to do it properly one should
allow for diffrent voltage and current ranges as well as diffrent
waveform frequency, all in order to measure diffrent things.
A professional tracker can do these things. It is not tricky cursuits
in itself and can all be built pretty well with fairly cheap
components.

Cheers,
Magnus