[sdiy] Rectifier for logic level pulse?

[Tim Parkhurst]

On Mon, Sep 28, 2009 at 6:00 PM, Harry Bissell <harrybissell at wowway.com> wrote:
> Hmmm... rectifying the pulse might be tough... how wide is the pulse ?
>
> If its a square wave it would be easy with passive components, if its a narrow pulse
> its quite tough. One side would have to reset very quickly.
>
> H^) harry
>

My original intent was to work with a square wave, or even perhaps
with the relatively slow pulse you'd get from a manual push button.
The solutions suggested here seem to generally work by inverting the
pulse, and getting one positive-going pulse from the original input,
and the other positive-going pulse from the inverted version. I can
see how this would work, but I could swear that I had seen a passive
solution that used a few diodes to full wave rectify the
negative-going pulse (prolly should have stated that at the
beginning). I mean, if you can rectify AC to produce a positive only
waveform, couldn't you do the same with the negative pulses you get
from the cap in a differentiator? Still, if adding an inverter is the
simplest solution, then that's hardly the end of the world.

Tim (relatively slow) Servo
-- 
"Sire, the church of God is an anvil that has worn out many hammers."
- H.L. Hastings