Electronics Basics: Reading current?

DrSid said:

I did not say anything about holding something in your hands. Some drivers can be used with open circuit, some can't, and capacitors can complicate everything, but that all are different (though relevant) problems.

Imagine you want to measure current-voltage graph of the diode. That can't be done with test load, you need actual diode.

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If you're doing tests of that magnitude of professionality, you're not going to use a DC/DC converter to power a diode, for Christ's sakes. That's what bench current supplies are for - taking very precise measurements and tests.

Or if you're just curious about some of your diodes and doiing a test, LM317 with adjustable current sounds perfectly fine with that.

Not holding it in your hands? Then what, you're going to solder the damned DMM probes to a PCB? And I've seen people do that, if you can believe it.

I believe You could solder a resistor in series with the diode and measure the voltage across it as if it were your test load. You probably shouldn't do it as it will increase the current and voltage draw the diode is seeing by the size of the resistor. At lest that's what I think.

Soldering the DMM leads is a classic.

Not holding it in your hands? Then what, you're going to solder the damned DMM probes to a PCB?

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I could also imagine using tiny crocodile clamps as DMM probes.

anselm said:

I could also imagine using tiny crocodile clamps as DMM probes.

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I would not do that myself either. Mechanical contact is not tolerable in this situation.
Only firm solder connection would be good. Unless you do not consider the diode and driver in question worthy of the trouble.

Seriously guys. Is it just me, or you all keep coming up with excuses not to do some soldering? Just to prove me wrong?

I cannot imagine one situation where a preset-and-forgotten flexdrive with well known testload is not enough, where you have to measure the current into the diode realtime and it must be flexdrive.

I'm not saying you are wrong, in fact I agree with you that between the driver and
the diode is a bad place to put a meter.
I'm just saying that if you'd had to do it, there'd be ways to do it.
Even if normally you wouldn't want to do it.

Oh yeah, well, that is a good point. But with all this, let's hope you never *have* to do it

Have a spare diode waiting in the wings if you try it!

great thread- thnx to all who added the great info- this one needs a (noob) sticky