>
> Somewhat inspired by Byron's TLVP I've wondered how trivial it was
> possible to make a HVP.  Here's what I came up with for your scrutiny
> (see attachment)

Well thanks for the encouragement.

* You need a current limiting resistor from the output of your IC1D to the
base of the transistor.

* Double check the input impeadance required on the 13V line. I always read
that MCLR should be tied via a 100 ohm resistor or so.

* And like my TLVP you need a 1k resistor or so
right after the output of IC1A so that the PIC can overdrive the output
of the parallel port. Otherwise you'll burn out the buffers on either the
PIC, IC1A, or both.

>
> Replacing the PIC-VDD control line with a straight connection to VDD
> might be a better option.

Could be. I always worry about hot plugging PICs into a socket.

>  Other than that, well, there's not much
> draw on the +13V line, so why bother with a complex circuit to
> control it?

True.

Cool circuit. Make sure to note as described that it'll only work with a short
cable. I have a developer who is working on a transmission line termination
scheme that I plan to incorporate for longer cables.

BAJ

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