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 Post subject: led design
PostPosted: Sat Oct 24, 2009 7:48 pm 
8086
8086

Joined: Wed Dec 12, 2007 9:03 pm
Posts: 69
Hello,

Not sure if this is the right forum? I'm a noob at electronics but want to make a solar powered flashing led pumpkin for a contest at work. I want it to be the logo of one of our companies with the lights flashing from the inside towards the outside. Here is a link to the logo, http://gosunward.com

It has 38 leds in each half plus 1 in the A.

Would you please give me a list of parts and instructions to make this?

Thank you,

Trent


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PostPosted: Sun Oct 25, 2009 3:25 am 
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cant give an exact parts list ATM but making it solar powered will cost. thats like over 130 LEDs (you want the letters too?) at 30-50ma (average) or so each = 5.5 amps at, say, 3-4v. solar panels cost. youll have to series-parallel them.

even just 77 at 30-50ma is 3.5 amps or so.

roughly here is what youre looking at.

* 77 LEDs (not so cheap, get in bulk maybe) many bucks
* 77 limiting resisters (cheap) few bucks
* 555 timer chip (cheap) buck
* capacitor and resister for 555 timer circuit (cheap) buck
* breadboard for timer circuit, power tab, and LED lead tie ins (cheap) couple bucks - might even be able to get away without this - how are your soldering skills?
* power transistor with heatsink to drive LEDs from 555 timer output (cheap) buck - use most any piece of scrap metal for HS
* solar panels to hit 4-5 volts at 3-5 amps under anticipated lighting conditions (not cheap) lots of bucks
* pumpkin - (cheap) couple bucks

555 timer IC is configured to as an oscillator, you pick the duty cycle with the cap and resister. it cant sink 3-5 amps by itself so you use the power transistor (with HS) hooked to its output to do that. the 77 LEDs are wired to the output of the power transistor and each LED gets a limiting resister so it wont burn out.


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