Small timer 'project'

[Barry Gower]

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

 

[Tom Biasi]

On Tue, 6 Dec 2011 09:10:53 -0800 (PST), Barry Gower
<barrygower@gmail.com> wrote:

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

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

 

[JeffM]

Barry Gower wrote:

no bigger than about 15 mm in diameter and up to say 25 mm thick,

As Tom said: Surface-Mount Technology.

when you press the switch,

Selecting a part that reduces the size of *that*

will be your biggest packaging problem.

a light (say LED)

What else would it possibly be?

flashes, at say 1 to 2 sec intervals for around 30 mins, then goes off.

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?

It would also be nice if it had a battery low function

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?

 

On Tue, 06 Dec 2011 20:01:45 -0500, Tom Biasi <tombiasi@optonline.net>
wrote:

On Tue, 6 Dec 2011 09:10:53 -0800 (PST), Barry Gower
barrygower@gmail.com> wrote:

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

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

Or learn to "roll your own"
http://www.picaxeforum.co.uk/

 

[Jasen Betts]

On 2011-12-07, JeffM <jeffm_@email.com> wrote:

Barry Gower wrote:
no bigger than about 15 mm in diameter and up to say 25 mm thick,

As Tom said: Surface-Mount Technology.

when you press the switch,

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

there's plenty of small SMD switches out there.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---