i have a portion of track where i would like the loc to slow down, all the time. Is it posible to insulate one end of the track ( iam on o scale 3 track), and put resistors in the track. example
_track________resistor_____track_______resistor_____track_____insulator)
i would be putting the resistor on the power line, instead of using a conection pin.
Just my oppinion: I’m not sure but it sounds like it would work. I think I have done it several years back. There’s not much chance of damaging anything (loco and power supply should be fine) but the resistor could become extremly HOT!!! Try using resistors in a parallel citcut to spread the voltage over a larger area more than one resistor.
Why? you can slow a loco with the power pack? If really nessessary then in SERIES with the track. and insulate at both ends of the slow bit.
Ken.
That should work, but normally this is the engineer’s job [:)]. One would have to make certain the two rails separated with the resistor “pins” didn’t touch in some other way. I did something similar on a children’s layout to force them to creep through a sharp curve that was after a very long straight. The long straight disguised how fast they got going.
Joey is right, the power rating of the resistor is a BIG factor, you’d have to use Ohm’s Law to calculate the right wattage rating needed and how much you want to drop the voltage on the rails. The problem here is if you run locomotives over these sections with different impedance rating for the motors, the speed change will be different for each loco.
I think you would be better off using a Potentiameter in line with the sections. They are a bit more expensive but would be better able to handle the power issues. They can also be adjusted for different locos, etc.
I don’t think this will work. You are not actually adding resistance between the motor and the power source, all you are doing is adding to the overall electrical load. Depending upon fairly complicated physics as well as the characteristics of your power pack, there may or may not be an effect on the speed, but the effect will be constant, not just limited to the section of track whose rails are connected with resistors.
You need instead to put your resistance between the power source and the desired section of track, which also must be insulated from the other track. Even so (as others have mentioned), the slowing will differ from loco to loco, and will be dependent upon the throttle setting as well.
And by the way, you will probably need at least 5-watt resistors for this, maybe even 10-watt given that you are in O scale. And they will get HOT so be careful.
Treating the ‘slow down’ section’s as a sparate block @ fed by a 35 watt W.W. resistor (HO) to 60 watt W.W. rersistor (O gauge) will accomplish what you want. They will get hot, which is why you want Wirewound’s - whatever the chosen value, You don’t want to start a fire.
5 amps X 12 volts AC or DC = 60 watts. The BAD news is WW’s cost a a few $$ each. The GOOD news is you only need one per block.
Running them in series as you diagrammed will be prohibitly expensive. Better to locate the Transformer the furthest away (trackwise) from a desired slowdown section, or have the Engineer slow down the train with a posted speed restriction, like the real RR’s do.
I’ll tell you what you need. Get a ballast resistor for any mid seventies Chrysler product. It’s house in ceramic, and even has a mouting hole. They can stand up to 20 volts with no sweat. On is a 1.25 ohm, the other is a 1.5 ohm. That oughtta do the trick. They are pretty cheap, too. Here’s three on ebay right here:
Why not put a dead mans switch into the block controlled by a normally open push button. The section would be dead unless the button is pushed, a reminder to slow down or the train comes to a full emergency stop!
Will
Using resistors to slow a train is possible, but not in the manner you suggest. The resistors that would susbstitute for track pins would not withstand the heat dissipation (power) requirements, especially for 3 rail O. Even if suitable resistors could be found, the length of locomotives compared to track sections would create problems. For instance, a locomotive would not see any slowing until all center rail pickups were in the slowing section. The same holds for the second slowing section. The center rail pickup with the highest voltage will be the primary feed to the motor.
Setting up 2 separate slowing blocks, each insulated with a separate feeder through a resistor, will work under certain conditions. This setup aids with resistor heat buildup because the resistors are only drawing power when there is a locomotive or lighted car in the section. The insulated blocks can be more than one track section to have time to affect the locomotive. However, for resistor speed control to work well, all the locomotives using the slowing section must have very similar current draws and operating voltages. The voltage drop across the resistor is proportional to the current drawn by the motor (or other load). If you are using a mixture of postwar and modern can motor locomotives, this uniformity will be virtually impossible to achieve. To drop 6 volts for a locomotive drawing 1.5 amps requires a 4 ohm resistor with a 10 watt power rating. If a motor drawing 2.5 amps enters the section, the resistor’s voltage drop increases to 10 volts - which will stop instead of slow most locomotives. Also, the power rating needed just went up to 25 watts! At the other extreme a power unit drawing .75 amps will see only a 3 volt drop, which may not slow it enough. Finding resistors that can dissipate 25 watts of power is not cheap - and you would really want them to be variable (0-10 ohms) to tune them to your equipment and speed restrictions. The last problem with variable resistors is what happens when the b
That would work too.
thank u all for the suggestions.
Here’s another one.I had a layout that I ran long trains on I built for a display,and I ran the trains fairly slow.I set the speed for the flat sections to go slow,but when it came to the grade,it wouldn’t make it.I isolated the grade,and ran a seperate transformer there.