Resistor question

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chiver
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Resistor question

Post by chiver »

Is it safe for a resistor to be touching FO? Or will it damnage it, also what's the best way to shrink, shrink wrap?
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Mr. Engineer
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Post by Mr. Engineer »

On a perfectly designed circuit, a resistor would not get hot... much.

But just to be safe, isolate the FO away from the PCB since all FOs now are plastic and prone to heat. I have never tried using heatshrink sleeves on a FO yet but I know that using soldering irons or heatguns or naked flames are the usual no-nos.

From the most websites, the minimum temperature to 'activate' the heat-shrink sleeves are 90ºC.
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en'til Zog
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Post by en'til Zog »

I've used heat shrink tubing on FO for years with no ill effects. It's the usual method for grouping FO to LEDs.

Just be gentle when heating the heat shrink. A heat gun used sparingly works well. I just hold the heat shrink over my (plugged in) low wattage soldering pencil and let the heat rising up geltly heat and shrink it. Do not touch the heat shrink to the pencil.
jkiker
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Re: FO usage but not the original question

Post by jkiker »

Hi en't,

This is not really aimed at the original poster, but your comments raise a question for me. I need some general light for the instrument panel and some FO for indicators around the cockpit; can I do both using the same LED? If so, how? And since I'm asking, pictures would be extremely helpful!

Thanks, Jim
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chiver
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Post by chiver »

You could try putting the light a bit further back from the panel, with some short FO pointing at the light
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en'til Zog
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Post by en'til Zog »

Hi.

Chiver's got it. Keep it simple.

If you have room, aim the LED away from the panel, and bounce the light off a white surfaced reflector back at the panel. That should diffuse the light, eliminating a possible hot spot.

You can drill holes in the panel itself & insert short pieces of FO through it giving you a glowing dot where the FO is surrounded by blank opaque panel.

For indicators around the panel just use short lengths of FO routed to "look" at the LED.

You can always remove any lens area from the LED (sand it flat) so the light spreads out more, then polish the resulting flat area and coat it with future/kleer to brighten it up again, if needed.

(Did I say "simple"?)

HTH
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