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Dark Detector

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tytower

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I got a circuit but I want a circuit that runs on 12 volts DC for a solar garden light project run on battery and solar panel.
To conserve power I would prefer to switch the light on with a transistor or darlington setup. I need it to be adjustable to come on when dark.
Here is the circuit I am starting with . Can anyone assist with a revamp with useable resistor , trany and LDR values please?
 

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Hero999

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For the benefit of other people that might want help with this, here's a link to the thread on the site where the circuit that the OP is discussing.

Dark Detector
 

tytower

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OK so I decided to keep the voltage divider at 10K either side and put a 3.3K resistor in series with the LDR I have . That gives me a 6V output for the comparitor and from 2V in daylight to 7.5V in darkness. That should work OK and multimeter tests show it does what I expect. Now for the comparitor and output
 

colin55

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Why don't you let the solar panel let you know the light-level.
When the output voltage from the solar panel is very low, the lights will come on.
If this is ok, you will only need a few components.
 

tytower

Banned
Why don't you let the solar panel let you know the light-level.
When the output voltage from the solar panel is very low, the lights will come on.
If this is ok, you will only need a few components.
Hadn't considered that ! Yes like a zener , say 10V , and take its output which is low bbelow 10V to an inverter ? but then still needs a tranny or relay setup.
Is that what you had in mind?
 

colin55

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You don't need anything exotic like a zener or inverter. Just two voltage dividers and a couple of trannys (trannys are transvestites where we live).
 

tytower

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Trannys are just switches I was taught when they started getting used in the early sixties . But then you are in Melbourne .

So how do you envisage using two votage dividers to get a low voltage?
 
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