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Led nightlamp - Help Needed!

 
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manjero
Newbie


Joined: 09 Jan 2008
Posts: 2

PostPosted: Wed Jan 09, 2008 12:17 pm    Post subject: Led nightlamp - Help Needed! Reply with quote

Hi.
I have a background in working with simple circuits i find from the net and modify a bit for my needs.
I'm also an EE student.

I want to build a nightlamp with leds. when turned on, 30 leds are on. every minute, one led turns off until all of them are off and the circuit does not restart.
I looked and found many sequencers that i could extend to 30 but i couldnt find one that keeps that led on.
Any thoughts?
I would prefer not to do this with a pic or other micros cause i never dealt with them and dont own a programmer.

Thanks in advance,
Shahar
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Nginuity
HG Ruler


Joined: 13 Nov 2006
Posts: 224
Location: Dallas, Texas

PostPosted: Wed Jan 09, 2008 12:48 pm    Post subject: Reply with quote

Perhaps you could do something with a few binary counters and some logic gates?

Look at schematics for a binary clock....basically, you'd be doing almost the same thing, except cutting a light off instead of on, and every 60 seconds instead of every second, but it seems like modifying the clock rate could do that.
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manjero
Newbie


Joined: 09 Jan 2008
Posts: 2

PostPosted: Wed Jan 09, 2008 8:39 pm    Post subject: Trying in JAL Reply with quote

Hi.
After reading a bit, i got to the conclusion that i should use a micropic.
i went with the 877a which i had lying around.
it has 33 i/o and i made all of them outputs and then wrote the jal software to shutdown led after led with the right delay between them.
just a couple of questions -
1. do i need to use transistors or something like that or the pic can drive all the leds together by itself (using 330 ohm resistors of course)?
2. except for the VCC and a 20 MHZ xtal with 2 caps do i need anything else?

Thanks in advance,
Shahar
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Nginuity
HG Ruler


Joined: 13 Nov 2006
Posts: 224
Location: Dallas, Texas

PostPosted: Wed Jan 09, 2008 9:18 pm    Post subject: Re: Trying in JAL Reply with quote

manjero wrote:
Hi.
After reading a bit, i got to the conclusion that i should use a micropic.
i went with the 877a which i had lying around.
it has 33 i/o and i made all of them outputs and then wrote the jal software to shutdown led after led with the right delay between them.
just a couple of questions -
1. do i need to use transistors or something like that or the pic can drive all the leds together by itself (using 330 ohm resistors of course)?
2. except for the VCC and a 20 MHZ xtal with 2 caps do i need anything else?

Thanks in advance,
Shahar


It depends on the amperage your LED's require. If the micro can source it, it may not be a problem. I still think you would be better off using the binary counter design, but it's totally up to you.
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