You could always have the time switch, photo switch and PIR in parallel, with logic at the back end to decide whether to turn the light on or not.
Well, come to that, you could have a light sensor and PIR (and any other sensor you wanted) feeding into a bit of programmable processing jiggery-piggery (which also contained a clock) and then just have a single relay on the output to turn the lights on and off as desired/required!You could always have the time switch, photo switch and PIR in parallel, with logic at the back end to decide whether to turn the light on or not.
. In that case, I don't quite understand what you meant by "...the time switch, photo switch and PIR in parallel....".Well I did envisage just a single relay at the end.
Yes, that ought to work pretty well (with "TOY" as well as TOD!) - but it might be 'more fun' with lots of inputsBut if you're going to get into programmable processing jiggery-piggery, you could almost certainly do without the light sensor. TOD ± an offset as an allowance for possible weather conditions would probably be fine.
On reflection, the battery might well be to just keep the clock going, with mains required to operate the relay.Even with an electronic time switch with battery backup, I'm not sure that it would necessarily work, particularly during summer - with (in my case) the relay having to be powered for anything up to ~7 hours per day whilst it was running on its battery alone.
Ah - did you stop reading, and not see "with logic at the back end to decide whether to turn the light on or not"?. In that case, I don't quite understand what you meant by "...the time switch, photo switch and PIR in parallel....".Well I did envisage just a single relay at the end.
Might be more fun if you built your own h/w using 7400 series ICs, but....Yes, that ought to work pretty well (with "TOY" as well as TOD!) - but it might be 'more fun' with lots of inputs
Yes, I did read it all. I guess that I don't properly understand what you meant by "in parallel".Ah - did you stop reading, and not see "with logic at the back end to decide whether to turn the light on or not"? I took it as read that the logic would not be able to directly switch the light.In that case, I don't quite understand what you meant by "...the time switch, photo switch and PIR in parallel....".
Jest ye not - I still make good and frequent use of such animals or, at least, CMOS equivalentsMight be more fun if you built your own h/w using 7400 series ICs, but....
I meant that the programmable processing jiggery-piggery (or the hard wired 7400 / 4000 logic) would have the external sensors connected in parallel, i.e. to 2 or 3 inputs.Yes, I did read it all. I guess that I don't properly understand what you meant by "in parallel".
I guess it's just another of those semantic issues! If they were connected to two or three different inputs, I wouldn't call that "in parallel". To me, "in parallel" would require that they were all connected to the same input - which would clearly be useless!I meant that the programmable processing jiggery-piggery (or the hard wired 7400 / 4000 logic) would have the external sensors connected in parallel, i.e. to 2 or 3 inputs.Yes, I did read it all. I guess that I don't properly understand what you meant by "in parallel".
Indeed.They're connected to one thing (the logic).
Again, indeed - which is why I personally would not describe them as being connected "in parallel". As I said, we obviously use that word to have different meanings.And none of them have their individual input/output connected to another's output/input.
All very true - but what has that got to do with what we are discussing?A logic output "fans out" to the inputs that are connected to it. A typical TTL logic device has a fan-out of 10 meaning it can drive 10 standard TTL inputs where these inpits each have a fan in of 1. Or the same output could drive 20 Low Power TTL inputs whose fan in value is 0.5 (of standard fan in). Or a mixture provided the total fan in is less or equal to the fan out of the driving output.
Whatever.Again, indeed - which is why I personally would not describe them as being connected "in parallel". As I said, we obviously use that word to have different meanings.
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