I have an older Pacific steamer that is DC, no electronics board. Loco and tender both have lights, but not directional. I want to replace then with LED's. I assume by doing this will serve two purposes. Give brighter lights and directional lighting. Basic question here is I don't know what LEDs to buy or what resisters to buy. Thanks, Ken
No, simply replacing the bulbs with LEDs will not give you brigher lights or make them constant or directional. Additional electronics circuitry is going to be required to achieve this. If you don't know anything about electrical wiring, you need to find someone who can help you because it's going to be too complicated to explain through these forums.
Just saying you have an "older Pacific steamer" is nowhere near enough information for us to be able to help you. What brand? What scale? What type of construction (plastic or brass)? Many more details needed about the locomotive.
Do you know how to take it apart so you can get to the headlight? Do you know how to solder? Do you have the necessary soldering tools? This is not something that can be performed without soldering experience and electronics knowledge.
Well, actually, with DC, a pair of LEDs wired together back to back will give directional lighting. It won;t be constant lighting, but one will be on when going forward and the other when going reverse. Wire the LEDs so that the anode of one connects to the cathode of the other, and vice-versa. Connect one side to the right rail via an approriate resistor, connect the other joint to the left rail. When going forward, engineer's side rail positive if everything is wired per NMRA standards, the LED who's cathode is connected to the right hand rail will light and the other one won't. For white LEDs an approriate resistor would be about 560 ohms. Possibly a 470 if your power supply doesn't put out much more than 12 volts at full speed (and I would presume you aren't runnign race cars here so you wouldn;t be at full throttle most of the time). The 470 would allow the LED to be bright at slower speeds and still be within safe current limits at 12 volts, but not much above it.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks cacole and Randy. I don't have the engine with me so I can't give you the manufacturer of it. I've had it about six years now maybe seven. It has a plastic boiler shell. The tender has electrical pick up from both trucks, but only for the tender light. There is no constant lighting or directional lighting in it. The tender provides no electrical power to the locomotive. This loco is never run at full throttle and the regular light bulbs that are in it are too dim and the tender and loco head light both light up. To me changing to LEDs will be a simple thing to do as both lights are directly powered from the pick ups and not through any boards or electronics. I have had the loco apart numerous times for lubrication and I have the tools and knowledge of soldering. I just needed the info on what resister to use and I assume the LEDs are 1.5 volts. I'm also assuming that if installed correctly, the polarity change from forward to reverse will cause the head light to go out and the tender light to come on unless I'm missing something here. I can't wire both LEDs together so it will be like adding just one LED in the loco and one in the tender so there will be no series type circuit except for the resister needed. Thanks again for your help here. Ken
If the loco and tender are isolated electrically, you'll want to use a regular diode connected in reverse with each LED, one for the loco and one for the tender. And one resistor for each set of diodes. LEDs are usually not very happy with sustained reverse voltage across them. With two LEDs back to back this allows the current to go through the forward biased LED. Since it probably isn't practical to run an extra set of wires between the loco and tender, a regular diode can subsitute for the 'missing' LED in each case.
For a steam loco you want a golden-white LED, not one of those bluish-white types. Unless your loco is an excursion loco with a modern replacement headlight. Miniatronics Yelo-Glo LEDs look good adn you can usually get those anywhere.
It sounds like we may be dealing with an IHC product that was made in Slovenia. I have several of these of various wheel configurations. The lights are dim because they use incandescent bulbs rated for a much higher voltage than what we normally run our trains at.
The problem I encountered with them is that the headlight is wired to the front set of drive wheels and the motor was wired to the rear wheels, with a bronze strip running from the front to the rear drivers for all-wheel pickup.
Getting back to your original question, most LEDs are rated at 1.2 to 1.5 Volts at 30ma or less. Wiring them as Randy said would require only an LED, diode, and resistor. The Yellow Glow aka Golden Glow LEDs would be best for this use, with a resistor value between 820 and 1000 Ohms. A small diode rated at no more than 1 Amp, such as a 1N4001, would be sufficient. When wired correctly, this will give you directional lights on both the engine and tender.
cacole It sounds like we may be dealing with an IHC product that was made in Slovenia. I have several of these of various wheel configurations. The lights are dim because they use incandescent bulbs rated for a much higher voltage than what we normally run our trains at. The problem I encountered with them is that the headlight is wired to the front set of drive wheels and the motor was wired to the rear wheels, with a bronze strip running from the front to the rear drivers for all-wheel pickup.Getting back to your original question, most LEDs are rated at 1.2 to 1.5 Volts at 30ma or less. Wiring them as Randy said would require only an LED, diode, and resistor. The Yellow Glow aka Golden Glow LEDs would be best for this use, with a resistor value between 820 and 1000 Ohms. A small diode rated at no more than 1 Amp, such as a 1N4001, would be sufficient. When wired correctly, this will give you directional lights on both the engine and tender.
Thanks cacole. I believe your right about it being an IHC engine. Light in tender is brighter then the loco light. Do I actually need a diode or will the reversed polarity blow the LED? Anyhow, thanks for understanding what I'm trying to accomplish here. Ken
Yes, the purpose of the diode is to protect the LED against reverse voltage. Even though an LED is itself a diode, they have a very limited range of reverse voltage tolerance before being damaged. The 1N4001 diode has a PRV (Peak Reverse Voltage) rating of 50 Volts, which is well within the range of our models. The additional diode will drop approximately 1.2 Volts also, which is why it would be safe to use an 820 Ohm resistor. Without the additional voltage drop provided by the 1N4001, I always use a 1K Ohm resistor with LEDs.
cacole Yes, the purpose of the diode is to protect the LED against reverse voltage. Even though an LED is itself a diode, they have a very limited range of reverse voltage tolerance before being damaged. The 1N4001 diode has a PRV (Peak Reverse Voltage) rating of 50 Volts, which is well within the range of our models. The additional diode will drop approximately 1.2 Volts also, which is why it would be safe to use an 820 Ohm resistor. Without the additional voltage drop provided by the 1N4001, I always use a 1K Ohm resistor with LEDs.
OK, thanks for your help and patience with me and you too Randy. Ya'll have a good New Year, Ken