At 08:03 AM 3/17/2004, jisak wrote:
>Hello Dwayne,
>I tried to search in piclist archives your"stoopid buffer circuit", but
>can't find it !
>Can you help me ?
>Thank you

Sure:  From Mar 7 2003:

You can try my stoopid (tm) buffer on the lines from the PS+: just haywire
up a couple of complimentary followers (1 each for clk & data).  I use
2n4401 / 2n4403: emitters connected together, bases connected together, PNP
C to gnd, NPN C to +5V, 330R between E & B, 100n Mono cap between the 2 Cs
for bypassing.  Bases go to the PS+, emitters go to the PICs being
programmed.  You really only need the 330R resistor between E & B on the
data line buffer but I put it on both lines in my setup.

When the PS+ is reading data, it does so via the 330R resistor.  When the
PS+ is sending data, the buffers help clean up the signal and provide
significant drive current if you are fighting other loads connected to the
programming pins.

Make the ground line from your board to the PS+ as heavy and low inductance
as you can.  Solder wick or the braided shield removed from RG-58 makes a
good ground line (shrink some tubing over it).

<end of copy>

dwayne

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Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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