On 2/13/2012 2:26 PM, Dwayne Reid wrote:
> You CAN make your own power supply - its a great early project that=20
> will last you for years. I built several small power supplies while I=20
> was a teenager (or even before) - the best units were based on LM723=20
> regulator chips with external pass devices. You can build a 1A or 2A=20
> supply easily but the heatsink starts to get HUGE as you exceed 2A.=20
> And - its hard to find power transformers that have multiple secondary=20
> taps at the proper ratios to do any good for auto-switching into your=20
> linear regulator. Most transformers have an available center-tap but=20
> you really need 4 taps or so to keep the heat sink small. dwayne=20

One easy solution is to move to a switching circuit for the conversion=20
from high voltages to lower ones. The LM2576 series of parts is probably=20
the easiest switching device I ever used.  Add a diode and an inductor=20
and it handles up to 3A.
Mark

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