[sdiy] Rectifier for logic level pulse?

[Ian Fritz]

>>... 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). ...

I've done this with (a) a high-gain differentiator followed by (b) an 
inverter, then diodes to select the positive pulses from each of these.

Ian