The subject tells the goal. Here is the rest of the story. There is no micro available. It is preferred to use a dual comparator such as
393 as one of those is already part of the design and having two of one device is preferable to one of these and one of those.I have tried and failed. Others care to give it a crack?
John
This is normally implemented with a flip-flop (bistable). You should be able to mimic the behavior with two comparators. See any college textbook on basic digital design.
Yes, I am aware of that design. Basically the switch provides a "clock" signal that flips the flop which operates a pass transistor. I may end up with that.
I just got the idea in my head that it could be done with one dual-comparator and am frustrated that I cannot figure out how to do it.
John
Also, another component is needed to debounce the switch. One comparator does that nicely so I was trying to combine two functions.
John
Why not wire up the dual comparator with mutual feedback and hysteresis; then use pulse steering capacitors and diodes (reference bistable multivibrator circuits from 1960's era computing) to effect a state change with an input transition on the trigger line?
Michael
I've used the Temic U6046B for this. It's actually a timer designed for car heated rear windows etc and includes de-bounce and a pretty high drive capability. Sadly no longer made. I've found a use for it on dozens of projects.
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Dave Plowman dave@davenoise.co.uk London SW
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