With an arm now on the signal, you’ll be needing a lamp behind it. I like to have working lamps in my signals and I have had a request to show how I fit these so here goes.
I use my own cast whitemetal combined lamp/bracket that has a 3mm hole for an LED to be fitted from the back but similar products are available from MSE or SSS. Some of these are designed to have a bulb fitted from underneath but the basic idea is the same.
Looking at the back of the lamp casting, drill a 0.8mm through hole in the lower left corner.
Bend the shorter leg of the LED (the “negative†terminal) back on itself as per the photo and thread it through the drilled hole. The body of the LED should locate in the larger hole (DO not glue it in!)
Where the short leg fits in the little hole, apply a bit of flux and secure it with a quick dab of 145°solder. This will be enough to hold it in position andenable you to change the LED should it ever fail without destroying the lamp casting. At this stage, trim the protruding leg of the LED from the front of the lamp case but leave the other one until the wire is attached later. Keep the cut off LED leg as you can use it as a ladder stay later!
With the arm in position, make a mark on the back of the post just below arm level and drill a 0.8 mm hole in the post. This is for the lamp wire. I use some very fine equipment wire I got from All Components which is thin enough not to show up too much but strong enough for the job.
With the signal post secured so it won’t move (in a vice preferably) and the arm set to danger, offer up the lamp case to the post and align the LED with the arm. This the fiddly bit…apply a bit of liquid flux to the joint and while holding the lamp case in correct alignment, carefully solder it to the post with145° solder. I use a 13watt Antex soldering iron for this job. When cooled, check that the arm clears the lamp when it swings up and down and the LED aligns correctly with spectacle holes on the signal in both positions.
Cut a length of wire off about 3†longer than the signal and bare about 7mm off one end. Thread the plain end into the hole in the post until it appears at the ‘ole at the bottom. Pull it through, leaving just enough to allow you to solder the wire to the long leg of the LED. Wrap the bared section around the long leg, tuck it as close to the back of the LED as possible and check it’s not touching the other leg. Carefully solder this on with electricians solder.
Trim the long leg off the LED as close to the wire as you dare and retain the offcut. These make useful ladder stays!
To complete the electrical circuit, solder an earth or negative wire to any convenient metal part (I usually drill a hole in the baseplate near the bottom of the post and fasten the bared end of the earth wire to it ) so that it will run next to the live wire from the LED. These 2 wires can then be taped together o run a sleeve of “heatshrink†tube over them.
Solder a 1000 ohm resistor to the positive lead, bare a little bit of the earth wire and you are ready to test the lamp.
The 1000 ohm (1k) resistor enables you to connect up 12v dc from your model railway supply or even a 9v battery.
Let there be light!
More soon
Jon F.
Very impressive Mr Fitness, I might even try that myself.
Jon Fitness' average 7mm signals workbench.
in Permanent Way, Signalling & Infrastructure
Posted
Dave.