Simple circuit in a flashlight to alternate between steady and blink with push button.

Could anyone tell me what the circuit in a led flashlight is that allows to it be alternately off, low beam, high beam and blinking with just a push button. Is there a way to achieve this without a micro controller. All the responses I can find involve the use of something like an arduino. There has to be a simple circuit for changing through the modes with just a button as the lights are quite inexpensive. Thanks a lot.

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iceng3 years ago

Buy the flashlight at the $1 store

diywannaber (author)  iceng3 years ago

LOL... If we were all going to do that I guess this site would get no traffic.

Nighter3D3 years ago

Hmmmm. well its easiest and cheapest to do by microcontroller like a ATTiny...

But its not impossible to do without. A button connected to a 4017 Counter (a common logic IC) with each output leading to a "Driver-circuit" which causes the individial modes (like output 0=off,1=low beam,2=high beam and 3 blinking). the 4017's 4th output would be tied to reset causing the chip to only cycle through 4 "modes". you would need a tiny debounce capacitor at the button to make sure it doesn't count wrongly.

The drivers could be simple transistors that let power through. The one that blinks would probably be a 555-Timer circuit to do the blinking.

It really is cheapest to just use something like an ATtiny. Cost for the chip is 3 bucks from SparkFun.

Picaxe 08M $2.95! (needs a programming lead as well though as a one off buy)

To do this with discrete electronics is really quite hard. A mechanical solution with a cam wheel and micro switch is easiest.

there are a LOT of cheap LED torches out there that do this - buy one and steal the circuit board out of it.

iceng3 years ago

Mass market Mini Microprocessor