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.
Sensor for illuminated house sign
- Thread starter dstill
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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!
Kind Regards, John
Well I did envisage just a single relay at the end.
But 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.
But 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.
. In that case, I don't quite understand what you meant by "...the time switch, photo switch and PIR in parallel....".
Yes, that ought to work pretty well (with "TOY" as well as TOD!) - but it might be 'more fun' with lots of inputs
Kind Regards, John
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On reflection, the battery might well be to just keep the clock going, with mains required to operate the relay.
Kind Regards, John
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.
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"?
Jest ye not - I still make good and frequent use of such animals or, at least, CMOS equivalents
Kind Regards, John
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.
I may have mentioned this before.
Tesco car park lights are mostly via contactors via a combined merlin gerin timer/photocell unit ( they do exist) and lights were on all night.
To conserve energy aprox 40% of the lamposts had an aditional din rail timer fitted inside the post.
Although it seems odd, they lose power for hours every day , but still spring into life and memory retained over 3 years since fitted and only a few appear to have failed, but possibly due to the envirement and damp issues
Tesco car park lights are mostly via contactors via a combined merlin gerin timer/photocell unit ( they do exist) and lights were on all night.
To conserve energy aprox 40% of the lamposts had an aditional din rail timer fitted inside the post.
Although it seems odd, they lose power for hours every day , but still spring into life and memory retained over 3 years since fitted and only a few appear to have failed, but possibly due to the envirement and damp issues
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!
Kind Regards, John
They're connected to one thing (the logic).
And none of them have their individual input/output connected to another's output/input.
And none of them have their individual input/output connected to another's output/input.
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.
Indeed.
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.
Kind Regards, John
All very true - but what has that got to do with what we are discussing?
Kind Regards, John
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