Small timer 'project'

Dec 06, 2011 4 Replies

Rate this thread:

Barry Gower 14 years ago

I hope someone can help me with this project.

I need a very small switch device, no bigger than about 15 mm in diameter and up to say 25 mm thick, and powered by a small watch battery. The device would have one main function - when you press the switch, a light (say LED) flashes, at say 1 to 2 sec intervals for around 30 mins, then goes off. That's it. It would also be nice if it had a battery low function so that the LED would say flicker continuously for say 15 seconds if the battery was below a certain useable level.

Many thanks

Barry

Vote

Tom Biasi 14 years ago

The circuit it's self is rather simple. The first requirement can be done with a 556 chip. The hardest part is your size requirement. Can you work with SMT?

Tom

Vote

JeffM 14 years ago

As Tom said: Surface-Mount Technology.

Selecting a part that reduces the size of *that* will be your biggest packaging problem.

What else would it possibly be?

The first thing you do when learning how to use a microcontroller is to get it to flash a LED. This one-chip solution fits your size requirements well. Enough said?

A battery-low indicator that uses up yet more battery power is so counter-intuitive. A microcontroller could use its onboard A/D converter to do this, however.

Isn't there a high school or community college full of nerds somewhere near you?

Vote

news 14 years ago

Or learn to "roll your own"

formatting link

Vote

Jasen Betts 14 years ago

there's plenty of small SMD switches out there.

?? 100% natural --- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required