alarm clock with led - with your help

[estersandro]

Dears,
this is a (little) dream of mine; to build a device, battery powered, which enables me to know, in the night what time it is. This is because I am no longer very young and after 3 a.m. I can be awake some times.
Therefore I think that such a device should switch on a red led at half past 3, and a white led at half past 4. Then a green led should be switched on (all the others off) at 5,00 and a red led should blink at 5.25. At this time I usually stand up.
How can I do this?
Thank you for a help

 

[Arouse1973]

Hi
But what if you fall back to sleep at 5.00 and wake at 6.00. Your 5.25 LED will be flashing but it won't be 5.25.
Adam

 

[estersandro]

it does'nt matter

 

[BobK]

I built an LED "clock" that changes color throughout the day. You can tell what time it is within about an hour by the color of the light. But that is not what you are asking for.

For your requirements, a micro controller would by far be the easiest solution. You would need a way of setting it, which could be as simple as connecting the battery at a pre-determined time. Then, if it is clocked by a crystal it should stay accurate enough until you have to change the batteries again.

Bob

 

[estersandro]

Dear BobK,
I think your led clock would be very good for me. Is it possible for me to "copy" it?
If you think that it may be of any help, you could also mail me directly :
legno(at)web.de

 

[BobK]

I actually do not think it would be all that good since it varies so slowly that it is difficult to tell the difference between colors an hour apart. For your purpose I would modify it to have an exanded scale, i.e. go through all the colors in the shorter period that you are interested in. You could make it start at red at 3:00 AM and go to violet at 5:30, so something like:

3:00 red
3:30 orange
4:00 yellow
4:30 green
5:00 blue
5:30 violet
6:00 red again (and cycle every 3 hours)

That would make it much easier to read the time in the period you are interested in. If you are interested, I could send you a PCB, since I have several extras. You would have to change the code and reprogam it.

What is your experience with building kits and programming?

Also, it would not run long on a battery unless you used a very low power LED and have it off except for the 3 hours you are interested in. I use a 3 Watt LED and run it off a wall wart so that it functions as a night light as well.

Bob

 

[estersandro]

I think the changes you are suggesting are exactly what I need. Yes I would use the weakest led I can find because I have to see it in the darkness from a very short distance. After h 6.00 it can (automatically) be switched off till 3.00 a.m.
My experience in electronic building is poor

Thank you

 

[estersandro]

Bob,
I am not an expert, but I can manage soldering and I know what capacitors and resistances are, and how they look like.
Please let me know how the device is to be built.
Thank you

 

[Elect Sign]

Dear Estersandro your dream and your project is really interesting. This is great fun to see the light is changing its color.