How Can I Change the Flashing Rate of a Battery-Powered LED?

[brian04]

Hey team i need some simple electrical engineering advice. I am a surgery resident and I need battery powered LED that flashes at 8 times a minute. Research funding is about as easy to find as health insurance so I am trying it on my own. I thought about just taking apart a flashing light that I use when i ride my bike to work but I am not sure conceptually the mechanism for changing the rate of the flash.

Project requirements:
- small (about the size of the old school plastic rings out of the 25 cent machines)
- battery powered
- 8 flashes per minute
- duration of flashing 2 hours max

I am thinking that I'll just build the circuit on a hinge so that when the attachment site is expanded to a hemisphere it completes the circuit and the light begins to flash. Any thoughts would be great. Especially on the timing mechanism.

 

[JimmyAlz]

The rate of flashing is most likely determined by an oscillating circuit.
These usually have a component called a capacitor that sets the flashing rate.

So:

I would go with the bike light, especially if you have no previous EE experience.
Buy some capacitors of varying values, for instance:
0.01uF, 0.1uF, 1uF, 10uF.

Then while the circuit is running, try connecting the capacitors you bought parallel to the
capacitors in the circuit and see which one changes the flashing rate.

You will not damage the circuit doing this, just be sure to use the correct polarity.
(capacitors have a mark on them indicating polarity)