Thanks guys, much appreciate all the replies. Some neat ideas to
follow up there.
But even while composing my OP it was nagging away at me that I'd
asked essentially the same question before. Further digging this
morning turned it up:
Subject: 2 pulses from 1
Date: Mon, 28 Feb 2005
Premature senility aside, I'm guessing that the reason it had slipped
my mind was that, although I had two great solutions from Fred Bartoli
and Fred Bloggs, I'd managed to come up with something trivially
simple myself that seemed to do the job. In fact, then and now, I'd
ignored the obvious: simply invert one of the inputs and use a vanilla
RC differentiator on each.
This was the circuit I used then.
http://www.terrypin.dial.pipex.com/Images/CurtainTimerAddOn.gif
I'm pretty sure that was what I implemented, and the gadget has been
working OK in the 16 months or so since.
The key difference *this* time is that I hope to feed these +ve pulses
(or squared up versions of them) not to a 4001 bistable but to a 4013,
as mentioned.
I haven't got around to that stage yet, so would welcome any feedback
- especially if my idea is a non-starter. I want the 4013 to achieve
the following 3 things:
1. +ve pulse A to Set pin 8 always sets or keeps 4013 output high.
2. +ve pulse B to Reset pin 10 always resets or keeps 4013 output low.
3. A +ve pulse T (from another source) to Clock pin 3 always toggles
the 4013 output.
For background, the practical application is a garden lights
controller for my son. At present the lights have an on/off switch
inconveniently located in his shed/garage at the bottom of the rear
garden. My unit should
- Switch (or keep) the lights on at dusk
- Switch (or keep) the lights off at dawn
- Toggle the lights on or off at any time from a radio signal from the
house, improvised from a wireless doorbell adapter.