Reverse lights for your locomotives

Discussion in 'FAQs' started by kf4jqd, Mar 21, 2001.

  1. kf4jqd

    kf4jqd Active Member

    Hello All:

    Yesterday, I was at the nieghborhood hobby store. I was talking to the owner about adding reverse lights in my locomotive. He showed me a package of them. A single light would cost almost $10.00. I thought that was too much.

    I examine it closer. What I saw how it works amazed me! PLus, I should have known better. Here's how they are made. They used a diode and a light bulb.

    "Damn". I said to myself.

    You can get a package of 2 diodes for under a dollar at radio Shack. Lights, just the same.

    A little while ago, I was going through my Ham Radio junk box. I found some diodes. I took them out. I took off the locomotive from the tracks. With some jumper wires and turning the power to the tracks. There was no light. Then I put the power pack in reverse. "I saw the light. And I was please!"

    So my advice is. Get yourself some diodes and lights for under $5.00 and get those locomotives with reverse lights!

    I tried this with a signal light. It works but the lumination of the lamp is equal to what the power pack is putting out. I think adding a relay to add a constant voltage will help.

    See you all later,

    Tech note:

    Think of it as a one way street. The voltage/current can flow ONLY in one direction. Reversing the voltage/current, will turn it off.
  2. George

    George Member

    Could you substitute an LED so you would never have to go back and find/replace hte bulb?

    George the Bulbophobe.
  3. kf4jqd

    kf4jqd Active Member


    You sure can use a LED! Just remember about that droping resistor you must add.

    Here's an idea. Use a bi-color LED. Going in one direction the LED could be red. Going in the opposit direction. The LED could be green. Any ideas where this idea can be used?

  4. kf4jqd

    kf4jqd Active Member


    I forgot to tell you something! The LED is already polarize. So this means you don't have to use a diode! Just add a resistor and you are ready to go. [​IMG]

  5. Dave Harris

    Dave Harris Member

    Andy, Did you Know you can have not only directional lighting BUT ALSO constant intensenity light using diodes? By using a full-wave bridge rectifier (about .89c 1/4"sq X 1/16"--Radio Shack) wired to 1-1/2 volt bulbs you have a bulb full bright as soon as the power is on.They are simple to wire in, if I can find a scanner I can send a diagram if anyone wants.

    L V Dave
  6. kf4jqd

    kf4jqd Active Member


    How can you have a constant voltage with a recifer? Voltage in equals voltage out. All they do is convert AC to a "dirty" DC. I would like to see that schematic! [​IMG]

  7. Voice

    Voice Member

    Andy, a diode will drop about 1 1/2 volts, and only that amount, any time its in a circuit. By going across the diode, you can use that voltage difference between the two ends to light a lamp. So, a 1 1/2 volt lamp will be on full bright as soon as there is more than that voltage across the diode. Of course, you're better off using a slightly higher voltage bulb, so that it doesn't burn out.
    Just a little more information,

  8. George

    George Member

    Stupid question time... [​IMG]

    If this is all so simple to install, and effective, why don't the manufacturers wire their products this way?

  9. kf4jqd

    kf4jqd Active Member

    Well George:

    To answer your question, it's simple economics! If the manufacturer was to add this simple light. They would probbly raise the price of the locomotive by $20!

    "Why, you asked?"

    Just think of the cost to install it. They would have to add 2 more manufacturing stations. In return, they would have to hire people to be at them. And if they pay the employee's both $9.00 an hour. You are already at the $18 area of the $20. So the left over parts would cost a $1.00 and the company would make a dollar profit!

    If I was a company owner, I would leave this out also. However, I would let it be known to my customers how easy it is to put the lamp in!

    I hope this helps, George. [​IMG]


    Little bit of bio:
    I currently work for a window manufacturer. Last year I worked on a process called Demand Flow Technology. This is a manufacturing process developed by the Japanessee. So I was able to learn on how a company makes money on their product. Quit interesting.
  10. Dave Harris

    Dave Harris Member

    Hey everybody, I goofed! The strictly diode package of constant voltage, directional lighting, uses 6 diodes not 3, which is why the F/W bridge is much better. It is a lot smaller package to stuff in someplace. ----Dave
  11. EM-1

    EM-1 New Member

    It all depends on the LED too. If you use a regular LED you'll have to use resistance on it. If you use the 12 volt DC LED you won't have to do much more then soldier your wires in acordance to the electrical flow. All can be had at your local Radio Shack. Be carefull guys because the if you don't use resistance on your LEDS it will cause a small explosion! and do harm to the light insert in your loco or car which ever you may be using. I destroyed a caboose with tail end lanterns that I installed LEDS in and never used any resistance and it blew the lanterns right off the body!!!! And also melted part of the body from the heat. [​IMG]
  12. Dave Harris

    Dave Harris Member

    Andy, This type of wiring has been around for quite some time. It was first used with 3 1004 diodes soldered together in a series with 1 reversed from the other 2 & leads hooked at the appropriate place, to in effect create a fullwave bridge rectifier. As "voice" said you can get a low voltage output across the diode, .7 volt , so pulling from 2 gives 1.4, enough to light a 1-1/2 volt bulb safely,without danger of bulb life reduction. The rectifier I mentioned from radio shack is much smaller , has 4 terminals to plug in to a circuit board . to use in the manner we want ,2 of these terminal are bent over a soldered to each other, these are the ones marked neg. & pos. Of the 2 that are left, 1 is wired to the power pickup from the track, the other to the motor, your light is hooked between the two. It's been awhile since I installed one so I don't remember for sure but you may have to hook a separate diode in the 1 light you want to be directional (reverse) By using this system you can use some tiny bulbs, less than a mm such as made by Mini-tronics. If you can't find the correct part at Radio Shack,E-mail me , I'll go to R/S & look up their part # .

    L V Dave
  13. kf4jqd

    kf4jqd Active Member


    As a electronics tech, I had to check the idea with the bridge rectifer. I guess the mathimatics speak for themselves. You are right. [​IMG]

    Everyone needs a Radio Shack catalog! They are FREE!!!!! [​IMG] You can also get one online at

  14. McFortner

    McFortner Member

    I hate to dig up an old topic, but it is talking about what I wanted to know, and my electronics is a little rusty! :rolleyes:

    I want constant intensity lights for both my engines and my passenger cars. I can see how connecting the bridge rectifier through the engine with the 1.5 v bulb in parallel would work for the engine lights, but what about the passenger cars? Would I put the rectifier in series with a resistor and put the bulb in parallel with the rectifier? And if so, what value of a resistor would I use? :confused: :confused: :confused:

    I worked 12 hours today and I am very tired and confused, but I feel I am close to a solution....:eek: :rolleyes: :confused: :( :rolleyes:

  15. kf4jqd

    kf4jqd Active Member

    Old Topic


    You can get constant voltage from the tracks to the passenger cars. You can build a cuircit that will give you a constant 1.5v. However, as a lazy person I am. I have experimented with Walthers, fairly, new interior lighting system for passenger cars. Try it. You will like it. Very simple to install. You don't have go through all that mess of soldering!

    I know about OT. However, the window business is slowing down. Barely working 40hrs and there's even layoffs! I want one to work on my trains. Oh well!

  16. N Gauger

    N Gauger 1:20.3 Train Addict

    Dave (and everyone else) I went to Radio Shack and they told me "no catalogs" this yesr - It's all on the website. I haven't seen a paper one yet his year....

    ~~ Mkey
  17. kf4jqd

    kf4jqd Active Member

    No RS catalog!


    Radio Shack has stopped publishing their catalog. They believe everyone has the internet and can check there. Another bad idea RS did was putting their parts in drawers. You can't see them hanging anymore! :mad: One last thing, they want to get out of the parts business. The local Ham Radio clubs are boycotting RS for treating their main customers like poop!

  18. McFortner

    McFortner Member

    Re: Old Topic

    Ok, I'll bite, just how would I do it? Use a resistor in series with the rectifier then the light in parallel with the rectifier? I'm still a little "loopy" from all the overtime I've been doing lately and it has been about 10 years since I last did electronics in the Air Force.

    OT, I had the displeasure of going to Rat Shack this afternoon. Even with my diminished knowledge of electronics I knew more than the suit wearing drones in there. I remember when you could go to RS and find somebody who knew electronics who could help you out and they had the parts to do it! Now they are just an undersized version of Circuit City. :( :( :(

    *sigh* Things sure have changed....

  19. davidstrains

    davidstrains Active Member

    Had a similar experience friday at our local RS. I asked the sales attendant about 6 conductor, flat wire for my DCC Loconet wiring. He immediately went to the TV coaxial cableing section to look for it. I suggested that it was similar to telephone wire. We looked there then the "boxed cat 5" and then I walked out.:mad:
  20. Vic

    Vic Active Member

    Re: No RS catalog!

    Hi Andy, I don't think I would have described R/S as politley:D :D
    I bet there's a million Radio Shack horror stories out there:D :D It just PO's me to ride by the place much less try to buy anything in the store.

    There are six R/S stores in this area. We're still using one on occasions but only because the manager and the sales people have "learned" to leave us alone when we come in and we'll find what we want. 73 de K4VIC SK SK SK :)

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