Use of Micro LED's for Lighting

[DKS]

To me the hardest (most tedious) part of the job is scraping the painted-on insulation from the magnet wire so I can make a solder joint (anyone have any helpful hints on this?)

Usually magnet wire varnish will come off if you dip the wire in molten solder for a second or two.

[peteski]

Usually magnet wire varnish will come off if you dip the wire in molten solder for a second or two.

+1. Usually I raise the iron's temperature to 750 degrees for this. I also dip the end of unstripped wire in electronic solder paste from Radio Shack. The insulating enable gets burned off and the copper wire is nicely tinned.  Some enamels are more heat resistant than others. Best way to figure out the best stripping temperature is to experiment.

[Loren Perry]

+1. Usually I raise the iron's temperature to 750 degrees for this. I also dip the end of unstripped wire in electronic solder paste from Radio Shack. The insulating enable gets burned off and the copper wire is nicely tinned.  Some enamels are more heat resistant than others. Best way to figure out the best stripping temperature is to experiment.

Thanks, guys! I'll give it a shot.

[VonRyan]

What is the smallest LED? (within reason of course)
What type of voltages are we talking about as well... 1.5v, 3v?

-Cody F.

[peteski]

What is the smallest LED? (within reason of course)
What type of voltages are we talking about as well... 1.5v, 3v?

-Cody F.

Smallest generally available SMD LEDs I've been able to find are 0402 (rectangular shape, 0.020" X 0.040" - thickness varies). Those sizes approach the limit of a person's ability to solder leads to them anyways.

As far as voltages go, you might want brush up on properly powering up LEDs (there is plenty of info on the Web about this).  LEDs need to have their current (not voltage) limited. They do have a forward voltage drop (depending on their chemistry), but what you really need to worry about it the current passing through them.

Those tiny LEDs are electrically identical to their larger counterparts. So whatever you read about the larger LEDs, will apply to the small ones.  The only specs which differs is the maximum forward current. Maximum current of small LEDs is usually 5-10 mA (larger ones can handle more current).

[unittrain]

I bought some micro LED's from ngineering sometime ago and hope to use them in my Traincat B&O and Pennsy signals, The only problem is I imagine I would have to etch a small circuit board for them then solder the LED's and any needed resistors to the board  . I would settle for just one signal aspect to have lighted signals.

[peteski]

The resistors do not need to be physically near the LEDs. The resistors can be hidden under the layout. Also, if only one LED (in a cluster of LEDs) will be on at a time, you might also get away with a single resistor (on the common side).

EDIT: for Pennsy-style position signals, a printed circuit board with LEDs on it would make sense.

[DKS]

What is the smallest LED? (within reason of course)

Within reason, 0402s as noted. However, there are 0201s and I've read of some plucky fellow who hand-solders them. They're extremely difficult to find, and IMO not worth the effort.