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darkmoebius 2nd March 2004 09:00 PM

Anyone ever use solderless breadboards for circuit testing?
I've been thinking about picking up one for testing out different powersupply filtering schemes (<36V battery only) and caps/filters in the GC signal path.

It seems like a good way to quickly try out all the different configurations everyone posts around here. :smash:

johnnyx 2nd March 2004 09:29 PM

solderless breadboard for power supply testing
I wouldn't use one for power supplies. The contact resistance could swamp differences in your filtering methods. I made measurements with MOSFETS switching 500mA on a solderless breadboard at college, and this was the source of the measurement errors compared to my calculations. I've never forgotten it. It would be better to point-to-point hardwire connections for power circuits, then you could be sure of your conclusions.

darkmoebius 2nd March 2004 09:47 PM

Thanks Johnnyx...
I figured there was a good reason why I'd never seen anyone mention them around here and it makes sense. :whazzat:

I'll just stock up on some decent perf board and wire. I'm not going to be doing anything too complext anyway.

Instead, I'll build a rotating bracket on stands that will hold the perf board and allow me to easily roll the board over for soldering on the bottom. I could even attach a few multi-jointed, locking, arms (like Pana-Vise) with alligator clips to hold components in place while I'm soldering below.

I'm sure they already exist, I just can't think of a name for them or where to buy.

orbital 4th March 2004 12:51 AM

About a year back I made up a LM3875 breadboard to try out a few configurations, with the output from a 25V 300VA toriodal rectified and connected onto the power tracks at the top of the breadboard.

I though it would also be a quick way to see the effect of different PSU caps. I soon noticed the huge difference in noise between different configurations - then realised this was due to component location - not the components themselves.

With the PSU caps next to IC, it sounded better than my previous amp, no hum at all. With the caps at the other end of the breadboard, the 100Hz mains hum was worse than any amp i've ever heard.

This finally convinced me how important it is to get your power/grounding arrangements correct - especially for a gainclone.

Anyway the upshot is that breadboard can be a good way of debugging dumb circuit errors, particularly for line level signal work.
It's not so good for power work, I built a big PSU that worked perfectly on breadboard but oscillated like mad on a PCB without the 'benefit' of parasitic capacitances between adjacent tracks on the breadboard, but I'd still recommend it as a starting point.

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