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How to create a simple on/off toggle button for small LED light?

I have these small LED spoke lights for bicycles. It operates by screwing the black plastic piece down to complete a circuit with the battery. Unscrewing breaks the connection. 

What I want to do is create a button that will complete/break the circuit turning the light on or off. I don't want the end result to be much larger than it is now if possible. The reason for he size constraint is because the light will go inside a small rubber ball. Squeezing the ball will press the button.

This seems like a fairly simple task but my lack of circuit/electronics experience (plus this head-cold) keeps me from thinking of a simple solution.

Maybe a toggle button is asking too much (too large, complex?). If so, I'd resort to have the light come on only while pressed down. This seems simple as well (bending a paperclip just right does the trick, but I'd prefer the on/off toggle.

I appreciate any tips and suggestions. I can also answer any questions to make things more clear if needed.



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-max-2 years ago

There are some simple circuit latches you can make using just a few transistors and a button. the EEVblog did do a video on it demonstrating it as a replacement for a toggle switch.

It used a MOSFET as a pass element, which connected to another transistor which served as positive feedback to the gate of the MOSFET, so that when initially powered, the MOSFETs off, and when a button is pressed to begin to allow a small current flow, the the feedback transistor began to turn on, turning on the mosfet, and then the thing latches on because of that positive feedback. However, that same switch controlled another transistor circuit at the same time to break that feedback temporarily, and then the MOSFET turns off. I do not remember the exact circuit, but I did experiment with it. I am sure you can find it if you search for it.

That will require a few components, and to miniaturize it, you can get the parts in small SOT23 SMD packages and build the whole thing on a custom PCB which you can design on some CAD files. Just send off the gerber files to a PCB production plant to have them make custom PCBs. You cannot get any smaller than that really, unless there is enough room for a physical latching button. like one of these:

http://www.amazon.com/Electronic-Button-Latched-Ma...

HEY BRO, ITS EASY, all you need is a spring a plastic cap and two pieces of metal, just adjust them .....

take two small pieces of metal , bind the two wires two it and then put a spring between them....

Toga_Dan2 years ago

buy a switch. or buy a cheap aluminum led flashlight and pull the switch from it. click on, click off.

Toga_Dan2 years ago

buy a switch. or buy a cheap aluminum led flashlight and pull the switch from it. click on, click off.

Some years ago I experimented with lights in a clear ball for my cats.
I wanted something that has a good battery life and fully sealed.
In the end it was getting a bigger task than expected as I included more and more.

Last was a wireless charger for the battery...

But the switching part was done with a tiny reed contact and magnet, well actually two as one was used to shut off and allow charging.
I used a thin feeler gauge blade to cut the switches and small screws to hold them in place.

Seasick Pirate (author) 2 years ago

Here are the lights and pieces.

image.jpgimage.jpg