OT- sourcing small LED's

I want to put a tiny lightbulb inside a small measuring devise, I'd like to use a housed LED with a soft flexible line going to a small battery housing (2 AA's maybe). I've dug around google and found thousands of things, but nothing like what I'm thinking of.

Anybody have any suggestions?

Reply to
overhere
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LEDs mostly come in standard packages (eg. 3mm diameter, 5mm diameter). Check any electronics distributor for the typical dimensions. You would do well to pick a standard type unless you have huge quantities.

You can get battery holders with two flexible wires, but you will need to join the two, and it would probably be wise to have a series resistor (at a minimum), particularly if the cells are replaceable.

You will be limited in type and color of light with only two cells and no sophisticated driver circuitry. White and blue leds have the highest forward voltage.

Using a sophisticated driver chip ($$) and a tiny SMT inductor (or a more complex but potentially cheaper discrete-based circuit), you can drive even multiple white LEDs from a couple of cells, even NiMH or NiCd cells.

Best regards, Spehro Pefhany

Reply to
Spehro Pefhany

I design these types of things on a daily basis...

Depending on actual size, an SMT led should work fine (Digikey -

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or Mouser
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You MUST use a series resistor (calculate resistor value as follows):

+V(source) - Vf(orward) / I (current through led) = R i.e. 3V-2V (red led typical) / .020=50 ohm resistor. A 1/8th Watt should be fine.

*Sometimes* you can get away without the resistor, but only for leds that have a high Vf (like blue or white. White is a blue led with phospher in it...). On cheap designs using red or green (not typically blue or white) you can use one resistor for multiple leds, but the leds should be matched pretty well or you'll get different brightnesses from the leds (due to current hogging...).

You don't mention if this is for a backlight of a display or just what, so hard to say what kind of dispersion you will need. If you give a little more detail, I might be able to offer a more complete idea of a solution.

Mike Tripoli

Reply to
Mike Tripoli

Thank you for the reply, this is for general lighting inside a 2" tall 1.5" dia measuring tool base, the operator has to look inside a "window" to align the product with a blade tip on the measuring devise. Presently we use a lot of overhead lighting, but this causes a lot of shadows inside the tool base. White or light blue would be preferred over any color.

I've got an LED probe light at home that's lasted for years, similar to item #3954T1 here

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that's what got me thinking about this...

Thanks again

I can send you an edrawing if you want to email me...

whit2

at

myway

dot

com

Reply to
overhere

Send your edrawing to mtripoli - at - jfww dot com. Is color an issue? With white leds, they can be tinted one way or another (towards yellow or blue). You don't really notice this unless you have an array of them, which in your case it doesn't sound like you do. Shoot me a drawing and I'll have a look.

Mike Tripoli www dot jfww dot com

Reply to
Mike Tripoli

You might also look a Lumex.com. They have lots of LEDs and LightPipes, etc.

Later,

SMA

Reply to
Sean-Michael Adams

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