Mr. Marley wrote:
> I would also like to know if there is any protective circuit I can
> build to guarantee I won't fry my onboard ports fiddling with this
> thing.

I've built a DT-001 too.

Power it up without the chips plugged in, and without it being plugged
in to the computer.  Measure the voltages at every point you can get
your probes into.  Check the 5V bus first, then the 13V programming
voltage.  If they are not right, turn off and figure out why.

Then test that the voltages on the connector that will be plugged into
the computer are all within the range zero to six volts relative to the
ground line on that connector.  If they are, then you haven't got any
pathological conditions yet that would cause damage, provided you aren't
using a power supply that is not isolated.

Run it from two nine volt alkaline batteries rigged in series if you
don't have any known isolated power supply.

I would also manually raise and lower the inputs to the board and verify
that the corresponding PIC programming line goes the right way.

If you have a spare parallel port card, use it instead of a built-in
parallel port on your computer.

--
James Cameron                                      (cameron@stl.dec.com)

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