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how can i turn leds on and off with a photoswitch? Answered

I wan t to turn 5volt  leds on and off .  They are on an outdoor project and I would like to turn them on at dark then off during the day to recharge the battery.  



8 years ago

Your project is a bit tricky, since you need 5 volts, and you want to power an LED (maybe several), but you need it to be solar powered and have a rechargeable battery. Here is an example of a 5 volt, solar-powered, battery-charging circuit:


I found this via discovercircuits.com, always a good starting point, but there are many other sources of schematics out there.

Anyway, the limit of the above circuit is that it's made from a cheap solar garden light, with one little 1.2v NiCd battery, and its tiny solar cells. This thing can only generate about 10mA of current at 5v, so multiple high-power LEDs are not going to work. This is for powering low-draw CMOS circuits or something. However, the principles behind this circuit - rechargeable battery driving oscillator producing AC power, and then being rectified into 5vDC power - can be your starting point to design a higher-powered version.

One thing to be careful of - this concept generates DC power by running its battery power through an oscillator and a transformer, stepping up the voltage, and rectifying it to higher voltage DC (5 volts). Depending on the circuit values and construction, this may also generate a lot of EMF that can interfere with other electronic stuff around, so building it within a shielded (and grounded) enclosure would be best (high-brightness LED flashlights are banned from my place of work for this reason).

Cheers and best of luck!



8 years ago

Start looking at this. If this is not what you want google "light operated switch schematic"

Whatever you build is going to drain some amount of power all of the time.