"And a heatsink [for the 7805] "

NOT to beat a dead horse, but what are the power
requirements so far and what is the expected
power budget for any peripherals?

What I am getting at is, the 78xx series (this includes
the 7805) *also* contains internal overload and thermal
protection (at least the data from National Semi shows
this - is this specific *only* to the Natinal Semi
parts?) and with mounting to the board and to any ground
plane on the board this *may* prove as adequate heat sinking
for the PIC on the PBK in normal operation without the
added complexity and noise of a switcher.

I have used the TERN TD-40 (which pulls over 300 mA total with
most of that consumed by a big, fat, 40 MHz 80186 5V processor)
with a 10 to 11 VDC unreg from a wall-wart and used a small
piece of AL sheet (about 3 cm by 6 cm) together with attachment
of the 7805 to the PC board -

- and the 7805 will gets warm but not excessively nor to the
point where it shuts down.

How much does a 20 MHz PIC draw?

RF Jim

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