This video is partly a test of using an iPad2 to record a video at my new workbench, which has been designed to facilitate a camera with suitable lighting. For this video it was just using a temporary setup of two 2W Philips LED lamps. (The actual lighting is ordered and on its way.)
The solar circuit is super simple. Just a transistor, two resistors, a diode and the small solar panel and battery pack of your choice.
The value of the two resistors can be changed to suit your own preferences. One sets the LED current and the other sets the darkness level at which the LEDs will turn on.

16 thoughts on “Simplest solar decorative lighting controller.”
  1. Avataaar/Circle Created with python_avatars Richard Sandwell says:

    Brilliant, the best circuits are the simple ones, the fibre optic wire that lights my toilet bowl when I go for a nightime pee is just a pressure mat, resistor, capacitor, mosfet and a LED with the fibre glued to the chip.

  2. Avataaar/Circle Created with python_avatars John Powell says:

    Just the job – possibly! I know nussink so am, literally and metaphorically, in the dark here.
    Could I substitute a YUASA 12v YTX20CH-BS AMG battery for the NiMH batteries and how would that affect the components?
    I'd like to have permanent strings of LEDs in several rooms, providing a night light/security light. I bought the (new) battery cheaply and have my own soldering iron. And some components. And a sense of adventure. But no insurance.

  3. Avataaar/Circle Created with python_avatars Jim R says:

    wow, great idea – I can't stop dabbling in solar cell outdoor lights and this is a great idea to make something very cheap using my 3D printer for lamp parts and some left over 18650 batteries

  4. Avataaar/Circle Created with python_avatars The wolf of Swingthat says:

    Clive, if I understand this correctly, when there is light, the solar panel generates electricity, but electricity has to pass through a big resistor to get to the base relative to the collector. Since voltage at collector> base. The transistor is off.

    When there is no light, battery pumps power through the diode to the base and then also take a detour through the 22k resistor to the led then to the collector. Since voltage at the base>voltage at collector, transistor is on

    Did I explain it correct?
    I still don't understand how your circuit protects flow of power from battery to solar panel.. will the battery hurt the solar panel since there is no protection?

  5. Avataaar/Circle Created with python_avatars shamem poilgram says:

    Thank you sir give me simple high amp soler street light circuit diagram with mosfet

  6. Avataaar/Circle Created with python_avatars DEADASTRONAUTFX says:

    Hi clive, ive been trying to add solar charge, and auto on at night functionality to a joule thief…….the joule thief runs great and for a few days on its own, adding solar charging and auto on would be brilliant, i jusg cant get my head around it……any ideas, links etc ?.cherrs man. .

  7. Avataaar/Circle Created with python_avatars Eddie Molina says:

    Thanks for the tutorial. It works!!-👊😁

  8. Avataaar/Circle Created with python_avatars John Anderson says:

    If the base doesn't have voltage during the night, how is the transistor going light the LEDs…? Is the base floating…? awesome video, I just did a similar circuit.

  9. Avataaar/Circle Created with python_avatars Talmiior says:

    I took a few electrical courses when I was going through college, but it taught none of the stuff I've been finding on your channel. Even the basics components tutorials you've put out videos on was barely touched in the courses I took. From just watching your vids, I've got to the point where I've understood how to merge two of the circuits you've featured on your channel to make another circuit, which I find quite exciting! I've been wanting to make a kind of battery operated night light that powers a string of low power LEDs. They're currently wired into a 12 hour timing circuit and 4 double A batteries, which the circuit just eats through. Using the joule thief circuit and the circuit you just featured here, I'm pretty sure I can make a circuit that could work using (hopefully) a tiny calculator solar cell simply as a light detector. I guess I could also skip on the double A batteries and just use a lithium ion battery and no joule thief, but where's the fun in that 😉

  10. Avataaar/Circle Created with python_avatars bbulliard says:

    I love the way you explain this in very simple terms. For this reason, it is a 'world class video' and appreciate you creating the video for me and others to learn how these things work. thank you so much….Bob

  11. Avataaar/Circle Created with python_avatars ssgeek45 says:

    No doubt its my clumsey work but-Just constructed this on a pcb. Checked several times everything correct but no voltage at led output acourding to ddm when solar panel is covered.used bc548 tran with 6v solar with a 3.2v lipo.used a 10+12k in series to get 22k. No current limit resistor fitted though.still no voltage at all……Ummm! It's out in sun.perhaps it might delight me when I get home tonight!

  12. Avataaar/Circle Created with python_avatars ssgeek45 says:

    Hi.can I use a 3.2v lipo with a 6 v at full sun brightness panel or would the batt be killed . thanks for you demos.supurb

  13. Avataaar/Circle Created with python_avatars PHB says:

    Nice but how can we avoid one volt drop at LED compaired to battery voltage. I didn't use current limiting resistor at LED.

  14. Avataaar/Circle Created with python_avatars Kanapki 436 says:

    What value or type of diode do you use

  15. Avataaar/Circle Created with python_avatars Ravi Kumar Manem says:

    Good explain. Thank you

  16. Avataaar/Circle Created with python_avatars ziplock9000 says:

    What common MOSFET can I use instead of the transistor for driving a bigger load (say 8v @ 10mA) ?

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