Hello, I'm new to the model train hobby. I was a member to another model railroad discussion group and the people were just ignorant. Since I was new to the hobby all they told me to do was look it up on the internet.(what's the point of forums then). I have read lots, and have collected lots of good and useful info. that has helped me a lot. Something I cant get a grip of is the electrical math. Here's my question finally,...I have just an average Bachmann 5 transformer, that has an extra 2 spots labeled 16v. Now my assumption is that one is for positive and one is for negative. The street lamps I have are labeled as 14-16v. Can I only wire one light to the transformer? Or is the math with ohms and watts and volts that complicated? Or,.... when I run the 2 bus wires under the table, and tap into it for each light, there has to be something in between the bus wires and light wires to alter the power? Sorry this is so long, I hope somebody out there hung in. Thank you in advance for any help.
I'm not familiar directly with the transformer you have, but many DC transformers also have a low voltage AC set of connections (typically somewhere between 14 to 18V AC), to allow one to power all their accessories. You don't normally have to worry about the amount of power available (wattage), unless you are building a large and intricate layout with lots of lighting. Voltage is the electrical potential between the two leads. A single 16V item, such as a light, doesn't "use up" all the volts. Just as with your house, where there is 120V AC in the plugs, you can plug in many different items onto the same circuit. What you want to make sure of is that you don't exceed the current draw (amperage) of the transformer's rating (just as you don't want to pull more than 15 amps in a normal household circuit, or else the circuit breaker trips). For what you describe, you should be able to hook it up with no problem.
Hello and welcome to the hobby! Since your lights are rated for 16 volts and your power supply says 16 volts, you should be good-to-go to plug all your lights in using a bus wire like you said. For the most part, you shouldn't need anything between your bus and feeder wires to alter the power (since they are rated for the 16v the bus wires provide). If you find a light is too bright, however, you can alter the power with a resistor - just make sure the resistor has a high enough wattage rating (I'd ask someone besides myself on how much that is if you end up wanting resistors). M
Hello, On an old layout years ago. I had 2 of the old tyco transformers, from train sets. One for each town on the layout. Each had 20 to 30 lights hooked up with no problems at all.
Welcome to Train Board bile. Glad to have you aboard. You can hook all your bulbs to the 16 volt connection on your power supply. If the bulb are too bright you can place a resistor in the same circuit to cut down on the brightness of the bulbs.
Wiring..... Wow, Thanks everyone. I assume that IF I needed to use resistors, that they would go at the end of the light wires, or in the bus right where I would connect the light wires?
If you mix LEDs with 16V bulbs, the resistors go only in the wires that lead from the bus wires to the LEDs. If you have only bulbs (or only LEDs) you should choose the resistor according to the formula W = V x A. V ist the voltage coming out of the transformer. A = ist the amperage of all bulbs or LEDs added together. You should choose a resistor with the next highest wattage. (e.g. 0.5W) hth Michael
Theoretically that's OK for only bulbs but can be problematic for LEDs. It should be OK if all the LEDs are identical but if any have a different Vf (forward voltage drop) you may find the ones with lower Vf grabbing the current. Best case the brightnesses will be skewed, worst case they'll burn up and you then get a cascading failure of the whole lot as the volts rise. The cascading failure could also occur with bulbs as once bulbs fail (or get disconnected) the voltage will rise leading to more rapid failure of the remaining lamps. To do it right you really need 1 bulb/LED : 1 resistor.
Wiring..... Cool, thanks, as far as I know I'm only using regular bulbs. But, I am ordering a few prebuilt, prelit buildings. Not sure whats in them yet.
Although I'm not an electrician, I do play one on TV.... You can also run your 16v bulbs on 12v, which would make them a little dimmer and make them last longer. Same thing with the lights in your house, use a dimmer switch and save on bulbs... I use less voltage for stuff like that to make it survive a little longer. The bulbs only have so long to burn before they go out.
No one has quite described the issues properly yet... Since your power source (16v) is within the range for your bulbs (14-16V) you should not need resistors. If your power source were higher, or you bulbs range were lower, resistors would be in order. You most likely do need to hook up each lightbulb in parallel. They way you've described hook them up - with two bus wires from the power source, and individual hook ups from the bus wires to each light bulb, is a proper parallel circuit. If you hook up the bulbs in series (in other words, in a row, with only the first and last bulbs connected to the power), the voltage to each bulb will be divided by the number of bulbs, and that will mean the bulbs will be dimmer. For example, if you hook up two bulbs, they will be approximately half as bright, or the same brightness as if you hooked up one bulb to an 8V source. In electrical theory terms... -In parallel circuits, the voltage to each component is equal to the power source (and current is added or subtracted). -In series circuits, voltage for each component is added or subtracted (and current is not). It's possible you will find it desirable to hook up bulbs in series, if you want them dimmer. It would be a simple way around needing a resistor if you were satisfied with the brightness level, say, of two bulbs in a series circuit. You can combine series and parallel circuits as necessary to achieve the result you're after. This is because the circuits in your house are all wired in parallel. The same only holds true modeling railroading if you wire your circuits in parallel. It is not always the case that you will do so. If lightbulbs are wired in series, then a single light bulb will "use up" all the volts, in the sense that you cannot add more bulbs to the series circuit without dimming all of them.
Sorry, but this is leaving out something very important. You need a different formula to determine the resistance rating (in Ohms) for your resistor, which especially in modeling railroading applications is more crucial than the wattage rating. You use the formula V = IR, or voltage equals current times resistance, where voltage is the voltage for the resistor (i.e. the voltage not "used" by bulbs or LEDS), and current is the desired current for the bulb or LED.
Wiring..... Thank you so much. I am thinking of keeping the lights all parallel. But I am also wanting to be able to switch off any street lamp and any building individually, so I know I'm going to need quite a bit of switches. I double looked. All my street lamps are 12v. But like I said before, I'm not sure what size the lights are in the buildings I ordered. I'm pretty sure I read in here about someone using a PC power supply. I have 3. Is that safe? If so and I can figure out the wiring,.. aren't these things big for the power,(so to speak)? If I can just get my table built fast enough. Patience...
I was the one that posted the how-to on converting a PC power supply. But, note: that will provide DC voltage. Here's the link . The lights should work fine, AC or DC, but check first. (easiest way is, if they are rated 12V, just hook up to a 9V battery). A PC power supply will give you +12V (typically two "circuits"), +5V, +3.3V, -12V and possibly -5V.
You may also wish to consider a master level variable resistor (potentiometer) wired in between the power supply and lighting circuit. Depending on how quickly you want to ramp up the voltage an Ohm rating of 50 – 150 Ohms will work. Just make sure to use a high enough watt rating to carry the full lighting load. Wire the positive lead from the transformer to the center point lug and the buss lead to either one of the end lugs. I plan to use one of my DC Kato Unitrack power supplies for this purpose. Jerry
wiring.... thank you so much.Ohh heck yeah there's lots of wires coming out of these things. Most of them have the same colors coming out. The red. black, and yellow. I gather they are technically serving the same purpose,. rerouting the power to different spots in the computer? This sounds like it would be a tough but fun challenge to make one.
Lighting questions: Well, as this is my first posting in this forum, I am going to offer a different approach to my lighting and voltage control. This I would think could be used for other situations as well. First I agree with the suggestions given in regard to the 16V power supply and the 12-16 volt bulbs. I have taken the regular little controller from a starter set, and I have connected my light to the "VARIABLE" side of the controller. The same side you would normally run your track wires to. Now if I have a line that requires 3 volts of power, I just gently apply the power until I see the bulbs burning at the correct brightness. Right now I have two of these controllers for two different voltages. But I can increase or decrease as needed without any problem. Harvey. I have the controllers built in under the layout, so no one gets to tamper with changing my power and blowing all my low voltage bulbs. Interesting, try it..
Follow the directions and links in the how-to. Most of the PC power supply wires are redundant for model rr purposes (yes, they are just to bring power to all the peripherals and different spots on the mother board), but you do need to place a load on the supply as well as a switch (or permanent short), to "turn it on".
wiring... Okay,...so I went ahead and played with a PC supply. I decided to build a small wood box to put it in and to mount all the posts, etc.. Also, I decided to take a separate computer fan and mount it on the box to keep it all cool. Now,..the fan says 12v. /.11amp. It has 1 red and 1 black wire coming out of it with a little connector at the end. Would I hook the red wire from the fan up to the PC red wire or does it need to be hooked up to the PC yellow(+12) wire? I am wishing it to turn on as the rest of the box and not having to use a separate on/off switch. Thanks.
Hook the fan's black wire to the PC supply black; hook the fan's red wire to a PC supply yellow (12V). It will go on whenever the power supply is on.
