> 2) The power supply is an old Motorola cell phone wall wart
> charger. It gives me about 4.6V @ up to 1.5 A

BTW James, is that a regulated supply ? I imagine it is, given
the end use, but you have to be very careful with wall warts and
you should measure the output before connecting it to any circuit

You might even want to characterise the voltage vs load

If this were an unregulated PSU, it might have 10V on the output
when unloaded (and a PIC is not going to draw significant current)
dropping to 4.6V ONLY when the current draw is 1.5A. I have
PSUs like that, some have a load warning label, some don't. A 12V
1A wall wart I use often actually puts out 19V unloaded. In most
applications I'll use a series resistor to dissipate some of the wattage
before a regulator. Rather a resistor heat up than the regulator


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