[sdiy] Rectifier for logic level pulse?

[Dave Kendall]

Hi Tim.

If I understand you right, how about a CD/HC4538 or HC123 dual 
monostable?
They can trigger from rising or falling edges.

Or possibly the one-shot circuits here;

http://www.musicfromouterspace.com/analogsynth/mmlogic.html

They look like they might do the trick, with a second gate used in 
series to re-invert for the rising-edge-to-trigger.
You get 3 free gates too :-)

cheers,
Dave




On Sep 29, 2009, at 00:22, Tim Parkhurst wrote:

> Hello Y'all,
>
> I'm looking for a circuit that SHOULD have been a simple thing, but it
> it escaping me. I have a circuit that take a CMOS level pulse,
> differentiates it, and uses a diode to lop off the negative pulse that
> occurs when the CMOS input goes low. Simple: one cap, one R, one D.
> What I'd like to do is add another diode (or three) and "rectify" the
> negative pulse. Essentially, what I need is a circuit that produces a
> short positive-going pulse when the input goes low to high (that's the
> easy part) AND another positive-going pulse when the input goes from
> high back to low (the not so easy part). This should be simple, and I
> can swear I've seen this done, but I just can't find it for the life
> of me. Should be just like a full-wave rectifier, right? I'm sure it
> will be a "D'OH!" moment when the solution is pointed out, but I can
> live with that.
>
>
> Tim ("Rectifier? I hardly even know her!") Servo
> -- 
> "Sire, the church of God is an anvil that has worn out many hammers."
> - H.L. Hastings
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