burglar alarm

[yoursoninoz]

Hi there

I'm trying to build a simple circuit to allow a low powered battery supplied blue LED to flash once the sun has gone down i.e at dusk and the switch off at sunrise (dawn). It's to fit into an imitation home burglar alarm box. I'm sure the circuit is very simple and I asking if you might have any info on what I would need to build such a circuit, I hope you find the time to reply and I'll look forward to hearing your suggestions.

Thanks in advance

Spencer.

 

[gramo]

Maybe the use of a comparator and a LDR (light dependant resistor) could do the trick?

Set the bias on the comparator to the desired voltage out the LDR that represents dusk

 

[House0Fwax]

This may provide the information you require.

**broken link removed**
741 Op-Amp, Light Sensor

You can easily replace the relay with a blue LED and a suitable current limiiting resistor.

 

[HarveyH42]

https://www.allelectronics.com/cgi-...LAR-CELL_W_CHARGING_CIRCUIT_-_1_RED_LED_.html

Guts from a solar yard light, $4.00. Replace the LED with a flashing type. If you'd rather change batteries, instead of solar charge... Remove the panels, and replace the batteries with a couple of C-cells