"Phil Allison" wrote in message
...

Trevor Wilson wrote:

I'm looking for a cheap and cheerful bench power supply. Here are the
desired specs:

50-0-50 Volts, variable.
0-3 Amps, variable.
Tracking

Ideally, I would like:

0-5 Amps
Linear rather than SMPS
230/240VAC


** All you need is one of these:

http://product-images.highwire.com/5569873/7432-6.jpg

plus a couple of 1.5V cells.

Gives you a dual tracking supply of 0 to +60V and -60V with single knob
control and heaps of current available.

Hint: you switch the amp to "bridge" first.






I had a very painful learning experience with one of these amps, in my very
early days of repairing stuff.

I'd repaired it, tested fine on the bench. Then reassembled it, stupidly
without re-testing it.

Turns out I'd used a screw somewhere near the mains switch that was slightly
too long.
Caused a short, caused both outputs to become DC.


Gave it back to the customer, he connected it to a pair of these:
http://spurwinkproductions.com/Edit%...res/813C_1.jpg


Fried all 4 cones.




Since then, nothing ever leaves my workshop without a final test, fully
assembled, ready to go.



Gareth.