On at dusk off at dawn controller

[KenTaylor]

I have converted what was formerly a kerosene burning yard lighthouse to LED (a multi color flasher from superbrightleds). I have a solar PV charger and a 6V gel cell battery. My next step is to add on at dusk off at dawn operation as the solar panel is a little underpowered with the LED burning 24 hrs per day especially during the winter.

I have seen many circuits for such controllers on the Web. However, I am looking for something very simple - sort of like whatever is used in the cheap solar powered driveway maker lights and such which are sold at Wally World, Harbor Freight etc. I find it hard to believe that they contain a sophisticated, adjustable op-amp controlled on/off circuit.

Can anyone point me to such a device or the circuit diagram? I am needing to control about 40 mA at 6 volts.

Thanks,

Ken

 

[Steve K]

I wonder if you could modify the controller circuit from a nightlight? It's just a photoresistor that controls the input to a triac, I believe. Not exactly rocket science. The circuit is designed for AC power at 115 volts, instead of 12vdc or so. I suspect that something similar could be done with a photoresistor and power transistor. I also suspect that it would require some tweaking to get it to work right. Maybe some positive feedback to get it to switch cleanly, instead of a slow turn-on and turn-off.

Steve K.

 

[Chris_Medico]

Why not use the output from the solar panel to shut off the LEDs?

 

[KenTaylor]

I thought of that however, the smallest relay I could find draws more power than the LED I am lighting.

 

[Christexan]

Use a power Mosfet, similar to a basic current regulator circuit, there is a simple one on instructables.com...
step 6...
http://www.instructables.com/id/E7QH8NG8I1EWOF32HJ/
except the "control" leg of the mosfet is turned "off" by input from the solar panel... the more power the panel outputs, the more it "shuts off" the mosfet, cutting off the LED during the day... I'm not where I can diagram it out or detail it more here, but it'd be a very cheap and simple circuit.