Very Simple Idea Help

[Mike96]

Hi, I'm making a clock and what I want is for when the hour hand passes/is passing over a certain hour (3, 6, 9, 12), an LED on that hour lights up.

How would this be possible?
Am I asking in the right place?

Thanks for any responses.

 

[Diver300]

You could detect the position of the hands with some opto switches like this:- OMRON ELECTRONIC COMPONENTS|EESX1106|OPTO SWITCH, TRANSMISSIVE | Farnell United Kingdom

Alternatively, you could do some clever metalwork and make something like this:- YouTube - The Big Countdown for the Chronophage where the lights that go round the clock are just slots in the metal aligning or not.

 

[Mike96]

Ok.. I guess I just jumped right in without looking.
I have no idea how that works, I was thinking it would be something simple but looking at the 'datasheet' for that, I'm way out of my depth.

And I don't understand how the second one works, though it sounds pretty simple.

BTW in case it wasn't blatantly obvious, I have never done electronics before.

 

[dougy83]

Perhaps a magnet on the hand & 4 reed switches mounted behind the clockface (obviously reed switches connect to the LEDs).

 

[transistor495]

The idea is not worthy on making on existing mechanical clock. If you're making a digital clock using a pic module then it would be easy to program. I think reed switch or any other mechanical arrangement will interrupt the free movement of the clock. Other things like a motion detector or IR interrupt based switching we can't do here . If you're a clock manufacturer then the below setup will work out.

*)Imagine you've placed holes corresponding to digits 3,6,9,12
*)There's a one more round plate below the dial attached to the hour wheel and a single hole corresponding to hour hand direction.
*)LED backlight.
*)Obviously the corresponding holes of digits will be lit when the plate moves below that

 

[Boncuk]

Hi Mike96,

the idea sounds great, but solutions depend a lot on the size of the clock.

You could for instance use reflective IR-barriers mounted behind the clock face and have them sense the hands through small (pinhead) holes.

There are real tiny reflective IR-barriers on the market focusing on anything between 2 and 10mm.

Give us an idea of your clock size, please.

Boncuk