I want to make a circuit that turns on and off the light (LED) of a given time (eg. on 9 pm and off 6 am). I also want it to be adjustable.
My idea about the design: I will be using an ATX computer power supply and 3 w LEDs. Control circuit is connected to +3.3 V or +5 V line for voltage conveniency. This part of the circuit will be responsible of opening the relay (switching on the light) at a given time of day and close it at a different time. It have to be adjustable, so I can change time settings.
The LEDs I'll be using is a cool white LED and a warm one, connected in groups like in drawing (one group being the same LED part).
Since the voltage of the LEDs is varying from 2-3 V I want to put 3-4 LEDs in serial, but I need to lower the voltage somehow (and regulate current?), because +12 V is too much.
(Cooling and heat sinks is no problem, I'll just connect fans to the +12V line and add a resistor.)
Since the PSU is a switched-mode PSU, is the linear regulator not needed? How can I connect these LEDs in very safe and efficient way?
I don't think NE555 is the right IC for this project. The best thing would probably be to buy a micro controller (àla Arduino) and program it (I'd have to read up on that). Or do you have an idea of how I can make the timer circuit?
Should I use the Panasonic TX-S reed relay? I've also looked at TI TS5A3157, but I don't think that is what I need (The TI is an analog switch).
Archived: Old, messy design drawing, newest drawing below: