Suppose for those who don't run DCC you wanted to have several trains on one track. The immediate problem becomes one of a faster train over taking a slower one and then you have to use the old finger method of slowing the faster train. Suppose you had several electrical blocks and you wanted to individually slow a particular train on that one block without affecting the remaining track. Does anyone know what value rheostat or pot one would need to insert in that section to be able to individually slow the train in that block? I saw it done back in 2004 in Seattle, but have never investigated what type of rheostat one would use. Can anyone shed some light on this idea? Thank you, Loren
Loren, A rheostat? I guess you are as old as they say. The quick answer is a 100 ohm potentiometer, linear taper in series between the track and DC. If you just want to slow a train, as in running through station, you could use a fixed value resistor and apply Ohm's Law. Example: The AZL GP-38 typically draws about 30mA. You want to reduce the track voltage by 1 volt. Ohms Law is R=V/I = 1/0.030 = 33 ohms.
typically with block control you have a rotary switch which allows you to choose which power supply to control which block and they can be changed as you move around the layout. In smaller systems a three position switch can be used to switch which one of 3 power sources you can feed the block. I have never used a delay resistor in block control except at dead end stations to slow train in last few feet before buffer to prevent a crash stop. I have also used a delay resistor in point to point auto reversing trolley lines so you slow down to a stop in stages with resistors before reversing and accelerating away from stop in opposite direction. There are several ways to do block control. one is at the location of each block there is a control which allows you to select the throttle you are using and connect it to the block and as you move to the next block you select you controller to power it and turn the power off in the block you left and turn power on the the next block you are going to enter and you control your trains as it passes block to block On some layouts to prevent two people or operators trying to use the same block you hang your tag beside the control so another operator can not select your block until you remove your tag. The other model is you call dispatch on a head phone to get your throttle connected to each block and each limit or before you reach it you call for the next block. In this way dispatch ensures ideally that no more than one train is in any one block or series of blocks by hanging a train number at the block selector. This is where DCC has really change the operating mode on large layouts. In block wring each train is controlled by a throttle and there are not reducing devices other than the throttle in use. So the number of throttles determines the number of trains you can operate. You also have to consider how many blocks you have. there is no point in having 6 throttles with only six blocks typically you have at least twice as many blocks as s as you do throttles for maximize the number of trains you can operate on at any one time on the layout.
The problem with resistors, potentiometers and rheostats is that different motor types will respond to them differently. No two motor types draw the same amount of current, so the resistance will have varying effect on motor speed, thus different locos will run at different rates. A superior method to make a "slow zone" is to use silicon diodes in series. Silicon diodes drop the voltage in a consistent way: each one creates a .75 volt drop, regardless of the current draw. You can put as many diodes in series as you need to get the amount of speed drop you want, as long as you have a matching set of diodes facing the opposite way and wired in parallel so trains can be run in both directions (remember that diodes only pass current in one direction). If you want to get really fancy, get a multi-position rotary switch, and wire opposite-facing diode pairs between the switch positions. You can then select from 0 to n diodes to control train speed as you desire, or even not at all.
Ah ha! I knew the obvious answer would emerge. Now off to find the right rotary switch. I doubt Radio Shack will be able to offer the one I need. I've got electronic supply catalogs so it's off to the hunt I go. Thank you all for the feedback.
Loren Let us know how you go, I find this thred you started really interesting, having a train slow automaticly at certain parts of the layout sounds cool, if you do end up doing something I'd like to see how you did it, Thanks Mike..
Mike, The idea is not to have the train slow automatically. When using just DC and several trains are on the same track one or more will over take a slower one and you are forced to 'put your finger on it' literally, in order to slow the faster train. My desire is to wait till the faster train that is over taking a slower one enters the controlled block, them manually slow it down to allow the slower train to gain distance between the two trains. At our local Railroad park in Medford, where I'll be tomorrow giving rides, we have the same thing in a manner of speaking. We have blocks that signals control as far as occupancy is concerned. When a train approaches a red lit block, it simply slows down till the block turns green. This is done without stopping and the engineer has the control instead of some jolly green giant on the side lines turning our loco throttles down. Same principle, only different scales. I'm going to go for the diode controlled multi-position rotary switch. This is the best one can do if not using DCC. I know right now the DCC boys are saying to themselves......."when is Loren going to come up to speed with DCC?" This is after all the 21st century and even this old dog needs to get on board. Some day, some day.
Loren, I have such a device on 2 blocks on my layout. It is possible to gradually slow down a train while it is in the block, without effecting the other train. Unfortunately, I have no idea what I have as someone else built it, but it does work. When you were at my house you saw it. Jim
To answer the OP's original question...and NOT harrass him! Not like me at all. If this hasn't been said, as I'm not going to take the time to read through all the posts. Purchase some DPDT's Center Off, (Double Pole Double Throw, Center Off) electrical toggle switches. Set up a analog DC, power pack as Cab A and another Cab B. Use feeder wires and cut in isolator gaps on both rails of your track. Now you can control two trains individually. There are plenty of How To Books out there you can purchase that clearly illustrate my Rick Approved CYA procedure. Grin! I'm in the middle or re-wiring my mainline linear control panel as well as my hidden staging yard. Now if you want to really make it complicated. Wire in a DPDT, Center Off toggled electric switch between Cab A and a DCC power supply. Now watch the sparks fly...ahhh....literally...or they could if you aren't careful. It takes some serious self discipline to bring all this together and work without crashing. I wouldn't operate Analog while in session with DCC. Not a good practice to operate them at the same time. Shut one off completely while operating the other.
Loren, Put in the "block" on the siding - insulate at least one rail both ends. Get one of those tiny controllers like, oh I don't know.... "e-Z Throttle" - just like the one you sell! Anywhoo...... Wire your track feed from the main power supply to the tracks into a 9-volt plug. Plug into the controller and connect the controller to the new block. Leave the controller on full throttle and as any train comes into the siding, bring it to a smooth stop. When ever you want to bring the train back out, you can bring the train back up to full throttle with the controller and the voltage should pretty well match: i.e. the train will be leaving the siding at the main power feed speed. Pretty simple, huh? :funny:
Never mind Loren's idea...pay attention to mine. Oh, of course I'ma kidding. Lot's of luck and let us now what you did and how well it works.
Just thinking out loud here... why is it when a modeler who is pleased and comfortable with how he runs his trains (which just so happens to be DC), gets harassed mercilessly by the "with it" DCC crowd? I know you may think it's all in good fun, but just beneath the surface is a bit of meanness that leaves a bad taste in my mouth. Kind of reminds me of how kids taunt each other on the playground... </rant>
David K, I'm ok with what David said. Besides, he drives a tiny car that scrunches his toes. so I am the one feeling sorry for him. I don't think there is 30 seconds air in David's car if he ever puts it in the canal. Careful how you drive Dave. ) Actually, I think Dave has a good idea regarding the hand held throttle. Now if I could only afford one of those but Karin won't give me a discount ) And David K, I don't mind the teasing......really. If I can't take it then I better pick up my trains and go fly RC planes instead. To the work bench I go.
Hey, I do have a legitimate question regarding sidings. Correct me if I am wrong. A siding would always be the alternative track would it not? In other words, the main line would always be straight through while the turnout would have to be switched in order for the train to go around and never the main line being the one that is switched? Hope that messy question made sense?
Isn't the siding always used by the train that is waiting? Try and leave the main alone. Do you think the controller idea would work?
Regarding the siding, I just feel the main line should always have the turnout thrown for straight ahead while the siding is used as the train slows anyway. Yes, I think the hand controller idea would work. I'll play around with it. If the idea works, I want the control knob to be built into the side of the module for aesthetics purposes. Boy, that word aesthetics is a big word for me. I'm not used to 50 cent words.
