Author Options:

How can I build a Slow, Rotating, Solar, Low Power LED for Mother-In-Law's garden lighthouse? Answered

I bought my mother-in-law a couple fiberglass lighthouses (hollow interior) that stand about four feet tall in her garden.  Is there any possible way that I could manage a low-power LED light (that doesn't bother neighbors), and not only make it slowly rotate, but power it from a solar cell off of.... say an old solar light?  Thanks!



5 years ago

Cunning trick to get a pseudo-rotating LED beacon of any reasonable height, which looks exactly as though it is being projected through a Fresnel lens (pronounced fray-nell after the inventor), use up to 20 strips of self-adhesive 3528 LEDs, stuck vertically around a piece of (say) 40 mm plastic pipe, inside an inverted plastic drink bottle. Drive opposite strips of LEDs from a 4017 decade counter via a transistor to ensure sufficient current. Best to use 120 LED per metre strip, from ebay, your choice of color, each 3-LED section draws about 16 mA. Use a 555 timer with adjustable time constant to clock the 4017 and get the speed right. There are plenty of schematics showing how to do it. Brilliant effect!


Answer 5 years ago

Well described, perhaps we can see a cool instructable from you soon ;)


7 years ago

Even a small motor will draw lots of power from a little solar charged battery.
I recommend you put a bunch of eight LEDs in a circle see the picture.
Only one LED lights at a time giving the illusion of light house motion.
It is absolutely Quiet.

If you like the concept we can change values for a lower voltage for solar day
charging and lighting at night.



Hi ICeng,

Apologies for highjacking this thread but I wonder whether you'd mind explaining how I'd build this circuit?

I have another post (my first) here https://www.instructables.com/community/Looking-for-LED-help/ and another member has suggested this set up might help me.


No problem,
This circuit is not acting exactly as you want.
The circuit lights one LED then the next, only one at a time, to simulate a rotating
light house beacon.
I thought you wanted, what I call a barber pole light.
This is where each added light stays on until at some point the lights
back down or reset to no lights at all.

I can probably show you a circuit for both, let me know ?
Either way people like to understand.



Thanks for responding. Yes what I'd like is a circuit which would light each LED at a time and remains on till all are lit (from left to right). Once they are all lit then I'd want them to all switch off in one action.

Thanks a lot for offering to help with the guide

One more circuit for 16 LEDs that get turned on by pulsing the SCR from
the sequential 017 singular outputs.
The SCRs must be chosen for a low value of Holding Current about 10ma.


Here is a pointer to  LM3916 Dot / Bar display easily does 10 LED any color
display which can respond to a pot or voltage input change.
I will follow  this up later with a16 LED circuit.
Of course you know a microprocessor is the way to go.........  A


Thanks for this. I'm going to give this a go in the next day or so. Although I'm a bit of a novice this looks pretty straightforward. Many thanks again!

I do like that idea; never even thought about it that way. I would enjoy it being solar-powered, if at all possible. Even if it only lasts a couple hours into the night. My biggest question, then, is if the lights alternate it a circular pattern, is it possible to dim on and off so that it's not such a sharp transition onto each light? Basically to still smoothly emulated a rotating lighthouse light?


Three ways to go,
  1. Add 8 more for a total of 16 LEDs and one more 017 IC, half as much movement per step.
  2. Use a micro processor and you can dim one led while starting the next LED.
  3. You have reached the point where a single LED shines up or down at a rotating mirror, is becoming the more feasible alternative.