Directional Lights for DC locomotives

Can someone please tell me how to wire directional lights. I don't
have a problem with the lights but at the moment they are on in each
direction. At the moment I will concentrate on white headlights but at
a later time I would like to know how to wire a rear light that only
works at the rear of the locomotive,
Thanks
Andy
Reply to
SquiddlyDiddly
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You need a diode such as IN4001 inserted in the lead from the right hand rail to the light bulb. ASCII representation of the diode looks like ---[__[]--- wire leads on each end of a small cylinder of black epoxy with a white band at one end. The banded end should be towards the light bulb. The diodes are quite robust and will withstand reasonable beginners soldering but holding the diode with a small pointed nose pair of pliers on the bare wire lead right by the diode might help.
Get some heat shrink tubing large enough to fit over the insulated wire and cut a length big enough to cover the bare soldered parts. Slide the heat shrink pieces over the wire before you start soldering and when that's done slide the heat shrink over your join and run the shank of the soldering bit gently over the heat shrink until it is tight. It shrinks about 50%.
You want to end up with the diode and heat shrink somewhere in the loco where it doesn't interfere with bogies turning, gears, body etc. etc. Turn the loco around and do the other end. If one contact of the bulb is to a metal chassis then you may need to reverse one diode. (ie turn it around)
The worst that can happen if you get it the wrong way around is that the light will be off when it should be on and vice versa. Wrong wire? The loco will only go one way. To much heat for too long? Wire insulation melts and causes shorts or plastic chassis or motor bogie melts.
If you have to solder near plastic a wet tissue over the bits you don't want to heat is useful.
Have somewhere arranged for putting the hot iron down safely and quickly - unfortunately we humans usually only have two hands and one set of eyes (generally focused on one spot) Soldering usually needs three or four hands. ( two parts to join - solder - soldering iron - ...)
The tail lights will want a diode soldered from the same chassis lead with the diode oriented the other way around ---[]__]--- Some bigger heat shrink tubing can go around the two diodes to hold them together. Last tip: melt some solder onto each of the leads you want joined before attempting to join them, that way you only need to hold then together and touch the soldering iron to the joint for about 2 seconds. BTW they aren't joined until the solder solidifies ;-)
Regards, Greg.P.
Reply to
Greg Procter
To activate a red rear light it is more economic to take a lead from the front (white lights) to the rear lamp. The rear lamps common lead will be the same as for the front lamps. Do the same thing for the reverse direction running lamps. The average diode can operate more lamps than can be fitted! Total diodes = 2. Any problems email me and I will send you a diagram.
Regards
Peter A Montarlot
Reply to
Peter Abraham
Chaps,
Your input has been invaluable and I am very much more confident I know what I am doing now.
One last question........... Can you recommend a supplier of LED's and resistors? I see Maplin do them but I always think they are expensive.
Andy
Reply to
SquiddlyDiddly
If you can get to a shop (and they actually have what you want in stock - LOL!) without incurring excessive travel costs then they can be competitive as you obviously don't pay P&P.
For mail order, Rapid electronics
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are very good but you do have to buy resistors in 100s (only 60p/100 last time I looked). Small orders (under =A325) will be hit by P&P charges.
Farnell
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will sell to anyone with a credit card willing to spend at least =A320, and don't charge for P&P.
No connections other than as a satisfied custoner.
MBQ
Reply to
manatbandq
I would recommend a visit to ebay, there are plenty of such things on offer. Resistors are usually offered in bundles and it is just a case of sorting out the useful from the dross -- just like real life really! If you have problems with the colour coding then just ask. In the long run it is really better to have a cheap and cheerful digi multi meter by your side -- mine never has a day off.
Regards
Peter A Montarlot
Reply to
Peter Abraham
LEDs packaged individually or a few at a time are expensive because the packaging/warehousing overhead costs more than the LEDs. Even the sales slip can cost as much or more than single LED - so guess what you are actually paying for. Sorry, no prizes. ;-)
Buy LEDs in bulk, 100 or more at a time, and the price be4comes reasonable. It's worth finding a few friends so that you can buy a couple hundred or more at a time. You will find many more uses for them than lighting locomotives. Eg, a cheap way to light carriages - a couple of LEDs will last a very long time when powered by an AA or AAA cell. Buildings can be lit with them, too. They are ideal for signals 9though the ones in larger plastic "lenses' will need some cutting down.) Etc.
BTW, the new LED Christmas lights are a source of cheap LED's - you get 50 for about $10CAD, much cheaper than the bubble-packed 3 for $4.50 at the local electronics pusher.
Reply to
Wolf
Try DCC Concepts. Richard is helpful, knowledgeable, and efficient. He can provide you with white LED's which representative of incandescent lights. The LED's come with the correct value resistors. He calls them "Prototype White" LED's. The light is soft enough to be realistic.
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Regards
Ezra
Reply to
Ezra Kowadlo

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