LEDs in kit

MiniPOV4 and previous versions

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bdaniels
 
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Joined: Thu Dec 18, 2008 12:29 am

LEDs in kit

Post by bdaniels »

Hi all,


I just bought the PCB for the MiniPOV3, Turns out the red LEDs I have are different brightnesses. I am going to try to go buy some matching LEDs tommorrow ;(

What LEDs are used in the instructions?

The voltage supplies will be 3v max, 2v drop, and 20mA for the LEDs.

So what is the best LED/resistor combo I can get so that they are as bright as possible with the given voltage?

(I know how to use the resistor calculator, but I'm not sure how that affects brightness, and how does MCD come into play?)

electron
 
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Re: LEDs in kit

Post by electron »

For LED's I don't know exactly which ones are used in the kit as I haven't built this kit, I have played around with my own on a perf board and I have found that the best LED's to use are ones with a wide viewing angle and high brightness. You should run them at the maximum current (mA) they are rated for in the datasheet to get the best brightness.

When I first tried it out I used some ebay 8000mcd 15degree waterclear 5mm LED's and the results were pretty bad, you could make out the words but you had to directly in front of it and the user had to wave it very straight as to not change the angle in respect to the person watching and even then it would be blindingly bright :)

I ended up using a dremel to grind the LED's lens flat and that made a really big improvement. It would likely help for better viewing angle if the LED's were diffused and not waterclear but I haven't tried that yet.

I hope that is of some help

Have fun :)

sparr
 
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Re: LEDs in kit

Post by sparr »

I used diffuse LEDs instead of the clear ones in the kit. I would heartily endorse this approach. The clear LEDs are awesomely bright if you stand in exactly the right spot, but diffuse LEDs give a much wider viewable range, which I think looks much better.

magician13134
 
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Re: LEDs in kit

Post by magician13134 »

Are you sure they're different brightnesses, if you have an image in your MIniPOV code, it will create the illusion that some are dimmer than they really are. Wave it in front of you (or a mirror) to see if that's the case. I would also go with diffused LEDs, though. Or you can diffuse them yourself by rubbing it with sandpaper.

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bdaniels
 
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Re: LEDs in kit

Post by bdaniels »

Yes I'm sure. I haven't soldered any LEDs onto the PCB yet. I just set them up on my breadboard with equal voltage and resistors.

Four of them are the basic red leds listed on sparkfun.com (brighter ones)

and the dim ones are the 3mm red at radio shack ( it said low intensity on the package)

adafruit
 
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Re: LEDs in kit

Post by adafruit »

the leds in the kit are diffused 400mcd or so

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bdaniels
 
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Re: LEDs in kit

Post by bdaniels »

thanks!

jmcculloch
 
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Re: LEDs in kit

Post by jmcculloch »

I burned up some MINIPOV3 LEDs testing them (you can tell I'm a n00b).

Will Radio Shack LED part #276-1622 work as a replacement? It's an LED assortment rated at 2-3V and 10-20mA.

The package contains two sizes, and the larger size has the same dimensions as D1-8 that came with the MINIPOV3 kit.

The Radio Shack LEDs are listed at http://www.radioshack.com/product/index ... b=features

Thanks,
Jmcculloch

jmcculloch
 
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Re: LEDs in kit

Post by jmcculloch »

I determined the Radio Shack LEDs work fine.

At first it seemed they were causing an issue since the last time I programmed the chip, everything was hunky dory. That was way back when my PC had a physical serial port.

It turned out AVRDUDE was returning an error due to a problem with my USB to Serial adapter. I solved that by plugging a serial port module into the mobo. AVRDUDE sure writes a helluva lot faster with the delay value remmed out!

Cheers,
jmcculloch

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