AW: Measuring the current draw of a modular

[Haible Juergen]

> Do you just snip the positive voltage line, strip it and run it through
> your multimeter via alligator clips?

I actually used to do this.
It's not a problem when I measure single modules.

For the whole *system* I will use a different method:
(Speaking of the JH-4 PolySynth)
As I need more current than a simple integrated regulator
would handle, I have to beef it up with an external power transistor
anyway. So I also need an overload protection, i.e. a
resistor which will produce some 0.7 V when the maximum current
flows thru it. Now this resistor is exactly the right place
to check with the meter. Simply measure the voltage across
this resistor, and calculate the current.
The resistor is large enough (by design) to give a reasonable
voltage at the current range of interest, and it's inside the regulation
loop, so you don't cause the output voltage to drop.

You might find this method exotic, but you'll be surprised
how many PSU designs have this current sensing resistor
already built in !

JH.