Tuesday, November 05, 2013

LED Lighting

3 LED light

Looking around for ways to light up the inside of my Wills signal cabin, I spotted a "canopy light" on Kytes Lights stand at Wycrail.

Consisting of 3 surface mount LEDs encased in a rubber strip made by 3M, the idea is that you feed 9 to 12v in one end and the LEDs illuminate. The strip is self adhesive on the back so can be fixed in place without any fuss.

Sadly, it was slightly too long for the cabin but peeling off the strip on the back, the copper tracks were easily visible. By cutting off the LED nearest the leads and then scraping away the glue and rubber over the tracks, it was possible to re-connect the leads so the remaining two lights came on.

Be warned, you have to do an awful lot of cleaning to get at the copper so it will accept solder. I thought just peeling away the rubber was enough but the tracks appear to be coated in something that resists fibreglass pencils and even the attentions of s scraper. I slid a scalpel blade along the stuff to peel an infinitesimal layer that still resisted solder away before a connection could be made.

2 LED light


Anonymous said...

Hi Phil,
The LEDs on these strips are grouped in three`s and electrically are in series with one another with a resistor to limit the current. When removing one LED you need to drop the supply voltage to about 8 volts or add another resistor, say 330 ohms or larger if running on 12 volts. Actually, adding a larger resistor may help and dim them a little.
I intend lighting my whole layout with these LED strips. Buy them on eBay from China. I have some which have twice as many LED`s, 3 every 25 mm, than the ones you have. Buy them in 5 metre rolls, 600 LED`s, for less than £8-00.
Brian G.

Andy from Workshopshed said...

I have an old tin of flux I use when soldering large connectors like this. Alternatively you can get an abrasive PCB cleaner which is like a pencil eraser, those normally do a good job of prepping the connections