You can implement a Schmitt trigger with 2 transistors.
Email me privately if you wish to pursue this.

Also. in similar pulse type applications you can often get magical
(*) improvements in pulse shapes with a simple 2 pole active filter
using an emitter follower, 2 R's and 2 C's.

Presumably, "The art of electronics" covers both of the above.


regards


        Russell McMahon

From: Alice Campbell <1502amc@LO.SCSENG.COM>
ive just spent the weekend trying to build an infrared comm link
between the pic and the serial port.  The reciever end is a
radioshack photodiode that switches the base of a 2n2222
transistor which runs through a diode to the rs232 Rx line.  The
problem is that the computer cant decode the characters.  it gets the
right number of gibberishes, in the right order, though.  i think
that the resistor is too sloppy to give clean voltage transitiions.
i looked in catalogs and cant find a shottky device with less than 14
pins, and i only need to clean up one signal, and hopefully cram
everything into a d-9 case.  Does anyone have any sound advice on how
to produce cleaner levels for the port using just a few parts?  or is
sending ir ascii a hopeless approach?
thanks,
alice