[sdiy] 4017 input shaping - LM324 alone?

[allanjhall at lineone.net]

> Now Ken, in particular, uses an LM358 opamp to controll the levels of
> both the clock and reset inputs to the chip.  For one, i wish to make

> the enable/disable input also availble from the outside, and also my 
> knowlege is not great enough to understand the additional circuitary going

> on the reset input, namely a 10n cap, and then a capacitor diode selection.

>From what I understand the (10n) cap in series with input has resistors
either side that go to ground this is to control the input pulse duration,
as cmos chips are fussy about trigger length, typically looking for about
2 to 10 ms length. Diodes are just to ensure that positive only pulse gets
to cmos logic chip, and op amp controls pulse level. 

cheers
Allan

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