May sound stupid...is it?

[petemoore]

Initial testing of circuits with lower pressure er voltage...low battery.

[petemoore]

If I could post a page, I would.
 I'd put stuff like trying rangemasters and FF's with easy to find, cheep transistors till it's working a bit.
 Check for battery shorts across + and - of clip..
 etc.
 Test the Ge in the DMM's Hfe checker to ascertain pinout...

[niftydog]

VERY initial testing, sure!  Like, is this connected to that etc.

Will tell you if anything is short circuit.

But won't help when looking at transistor bias or anything like that.

We sometimes use it at work if we're not sure if we've fixed a catastrophic failure.  Wind it up slow, and if it does blow up, hopefully it will blow before full voltage is applied! (less damage)

[Jason Stout]

Thats not a bad idea, if you are unsure of the wiring it may be good to try your Rangemaster/fuzzface circuit with $0.03 transistors before you put the high dollar germanium transistors in.

[R.G.]

It's a great idea - for power circuits.

One of my favorite tricks for debugging a power amp that blows fuses is to connect it to a variac and bring up the AC slowly, watching the current as it comes up. The other is to insert a 120Vac light bulb in series with the AC line so if it pulls too much current, the light bulb chokes the current off. There are very few fuse blowers that can't be debugged this way.

While it's certainly possible to get enough current from a 9V battery to damage something like a reversed electro cap, I've never seen a component damaged on a 9V battery setup except for a reversed IC package.

You might adapt the light bulb theory to effects by using a 1V/ma ...er... 1K resistor in the power supply line. That will limit current to no more than 9Ma even if you got it really wrong.

But I would not have enough patience to do that. Parts are cheap, time is not.

[petemoore]

I just like the idea that for the first fire up, I use a low battery, and listen for the telltale power on sound that actives make [when they're wired properly enough to turn on] then when they get powered up, to see if signal is passing.
 Without that power up sound [when the battery touches the clip], there's almost certainly a problem.
 Also this probly gives just a few seconds more time before stuff starts burning like wires or Mosfets.