You wire two diodes in anti-parallel, that is, with the cathode of one connected to the anode of the other. Then you put that in series between the transformer and the center rail. This will reduce the RMS voltage by about one-half volt. To get more reduction, put additional anti-parallel diode pairs in series with the first one.
The diodes' voltage rating doesn't need to be any more than 1 volt; but the lowest rating you are likely to see is 50 volts. The current rating should be about 6 amperes, like these: http://www.radioshack.com/product/index.jsp?productId=2062591&filterName=Type&filterValue=Rectifiers
However, you can make the equivalent of two diode pairs in series from one bridge-rectifier module like this: http://www.radioshack.com/product/index.jsp?productId=2062583&filterName=Type&filterValue=Rectifiers Connect the + and - terminals together. This becomes the point between the diode pairs. The other end of each diode pair is one of the ~ terminals. So you can get about 1 volt of reduction by connecting the module in series with the transformer using the ~ terminals. Note that, although this uses a bridge-rectifier module, it is not actually operating as a bridge rectifier.
Bob Nelson
lionelsoni A block system, like I described earlier, is safe and is what I would do (and have done). The inclines can be done with rheostats, but diodes give you better voltage regulation, since the voltage drop is independent of the current that the trains draw.
A block system, like I described earlier, is safe and is what I would do (and have done). The inclines can be done with rheostats, but diodes give you better voltage regulation, since the voltage drop is independent of the current that the trains draw.
What type of diodes should I use for decline? I am looking on amazon and the diodes seem to be for hundreds of volts. Do I wire them in series with the line supplying the decline block?Thanks!
lionelsoni - I have done more reading and I finally understand this fault you have been trying to explain to me numerous times (thank you for not giving up). I found a post that helped illustrate your point to me (kudos to you at the end):
"Konga ManFor a graphic (if ill-advised) illustration of the risks (of using different power terminals between blocks), try this: take two in-phase transformers (or one multi-circuit transformer). Run a jumper between the two common terminals. Run a second jumper between the two hot terminals. Apply power and start twisting the knobs. Would you feel comfortable doing that? Because that's exactly what's happening when a train goes between blocks. If you're interested in a more detailed explanation, Bob Nelson (username lionelsoni) has quite a few posts on the subject on CTT"Source: http://www.modeltrainforum.com/archive/index.php/t-7108.htmlI will create a new thread with photos of my layout and wiring ideas possibly later tonight to better organize my thoughts. Thanks again to everyone.I wonder if I should sell my new ZW. It seems the power pack can be rearranged among the 4 terminals, and now I'm unsure if this is a safe design.
Texas Pete "Word on the street" is that clean 275 watt ZW's were going for $95 to $125 at the big york show.
"Word on the street" is that clean 275 watt ZW's were going for $95 to $125 at the big york show.
I suppose the only safe way of doing it would be a powerful transformer like a KW or ZW, and having one terminal power the whole layout while using Lionel 95 rheostats on the incline and declines. I'm sorry to keep asking you lionelsoni, but you've help me much. Thank you.
gunrunnerjohn I have been tempted to take off the cover and give this a look see for myself. This would be my plan, your shop is absurd, those are inflated prices on an old transformer, even reconditioned! Fix yours, save yourself about $250.
I have been tempted to take off the cover and give this a look see for myself.
This would be my plan, your shop is absurd, those are inflated prices on an old transformer, even reconditioned! Fix yours, save yourself about $250.
Pete
"You can’t study the darkness by flooding it with light." - Edward Abbey -
That should protect wiring as small as 16 AWG.
There are other considerations in running between differently-powered blocks, that don't involve fire safety: arcing, voltage spikes, and damage to internal wiring.
o Depending on the differences between the voltages, you may experience damage to the rails or pickup rollers from arcing as the rollers connect the transformer outputs together and then disconnect them.
o When the outputs are disconnected, the stray inductance of the transformer windings can produce voltage spikes of hundreds of volts that can damage electronics in modern locomotives. Transient-voltage suppressors will protect against these.
o Many locomotives and lighted cars have two pickups connected internally by fairly light-gauge wire which can be damaged if it has to carry too heavy a fault current for too long.
RockIsland52 Generally speaking........ on a postwar ZW, how often do you more experienced guys find that the roller windings are worn out versus just dirty or an adjustment required? My repair shop observed I might be better off just trading in my ZW for one of the refurbished units they had on hand, @ $250-$275. The right side control which was the more frequent one used over the past 55 years or so
Generally speaking........ on a postwar ZW, how often do you more experienced guys find that the roller windings are worn out versus just dirty or an adjustment required? My repair shop observed I might be better off just trading in my ZW for one of the refurbished units they had on hand, @ $250-$275. The right side control which was the more frequent one used over the past 55 years or so
You can replace the roller, if you use the proper technique, it's quick and pretty painless. I can normally replace the two main rollers (the others never seem to be worn out) in about half an hour or less. The rollers and pins only cost a few bucks. I've never seen the windings "worn out", though if you run too long with a completely worn down roller, you can damage the windings.
Lionelsoni - Should I be safe if I install a 8 or 10amp circuit breaker on each transformer's 'hot' side as phillyreading suggests? Now I am going to read about installing command control should I decide to run conventional and command at the same time in the future while using my current blocks assuming the circuit breaker will protect me.
The right side control seems to have lost a tad of precision when increasing or decreasing power delivery right at or around the operating speeds most frequently selected. The left side control? No such issue.I apologize if my terminology is off a bit.
Jack
IF IT WON'T COME LOOSE BY TAPPING ON IT, DON'T TRY TO FORCE IT. USE A BIGGER HAMMER.
There is some information that one can get from what is visible of the wiring. However, the really important stuff is inside application-specific integrated circuits and in the firmware of computers inside the modern "transformers", which is almost impossible to reverse-engineer.
Will this work for blocks and block signals? 153? I would like to have two trains on a loop, and have the blocks automatically change from green to red while stopping the train to keep the faster train from crashing into the slower train. One 153 block signal should be sufficient for a loop with two trains? How many blocks will I need? Is there a website that explains this?http://www.amazon.com/Absolute-RLS125-12-VCD-Automotive-Relay/dp/B0056BPX64/ref=sr_1_2?ie=UTF8&qid=1319071752&sr=8-2I will work on getting internal pictures of the wiring in my transformers for you guys.
Except for a few details that I have come across for the CW-80's output circuits, I have no knowledge of what's inside the modern "transformers", most or all of which have a lot more in there than just an actual transformer. The folks who are advising you that it is okay to connect "transformers" together mean, I think, that they did it and nothing bad happened to their particular "transformers". I doubt that they or anybody has any engineering information to say how each "transformer" that you might use would behave when connected to any particular other "transformer" or transformer, because no modern manufacturer wants us to know what's in their designs.
It is not dangerous to use the various posts on a transformer (without quotation marks). It is dangerous to connect the posts together, because they are generally supplying various voltages at low impedances, which means that large currents can flow if they are connected together. The way that Lionel located the circuit breaker in series with the common means that connecting together any two terminals other than the common can produce a harmful fault current that doesn't flow through the circuit breaker, which will therefore not trip and will not protect the transformer nor your wiring.
When you run a train from a block powered by one transformer output to a block powered by another transformer output, you are connecting those outputs together through the locomotive's pickups (and through any lighted cars that have two pickups wired together inside the car.)
Connecting the commons of two transformers together does not make a circuit. You have to make some second connection to have a circuit. That is why connecting all your transformers' commons to the same outside rails is not a problem.
The only Greenberg wiring books I have seen are Peter Riddle's. I would avoid them. It is possible to be knowledgable about electricity, or any other subject, without formal training. But that is not the case with those books.
Am I reading these posts wrong? It seems like I have a handful of people telling me it is ok to use multiple transformers for one track, and some telling me I"ll burn my transformer (I most certainly don't want this to happen). That, or everyone agrees and I am reading something wrong. Here are some websites I found that add more to the confusion of multiple transformers. http://www.jwtrains.com/Tech%20Tip_6.htmWhat I don't understand, is if it is dangerous to use different posts on a transformer to get different voltages, why is it ok to use any common ground - they are all common? Doesn't that mean they are part of the same circuit?Lionelsoni - Do you recommend any books on this subject? Is Greenbergs Wiring for Lionel Layouts accurate? If so, which vol?Thanks so much to everyone! I have much to learn
There's no benefit from insulating the outside rails.
I've used multiple transformers to separately power sections of a layout - each powers a separate block or loop. There are track connections between blocks but only plastic or fiber pins in all three rails. So each engine essentially stays within its own blocks and just transfer vans or wagons between sections.
Doug Murphy 'We few, we happy few, we band of brothers...' Henry V.
Add fuses in-line for your various track blocks.
From what you are describing, I would buy a post war, 275 watt, ZW transformer and add 8 or 10 amp circuit breakers on the A, B, C and D outputs. You would have plenty of power for your trains and be able to power your switches by using either the B or C terminal and setting the voltage level with a volt meter or multimeter. The old postwar ZW transformers have only one circuit breaker(15 amp) and it is on the common side, does almost nothing to protect against over voltage between two outputs one track such as block sections.
To control a train or two using a 153 block signal, you will need to add a relay for automatic, or install toggle switches, into the circuit to interupt the power flow to the track.
Lee F.
None of your transformers(all AC, by the way) are pure sine wave. The MRC TrainPower O-27 is the worst with a very noisy output.
That's the bad news.
The good news is that if you can phase them all, you don't have to worry about the fault currents Bob is concerned about due to their electronic circuitry(as in the case of the ZW powered by PowerHouse bricks in the manual). There won't be a short, just a "takeover" of the higher-set throttle bearing the bulk of the load. I've done this with PowerMasters continuously for several years with no problems.
You still have an issue with your small 40 watt throttles. They aren't very robust, but if it's working, go with it.
Rob
"How can I make sure the instantaneous track voltage supplied to two blocks is the same frequency, amplitude, phase, and waveform?" You can't. That's why you shouldn't run between blocks with different supplies.
"Is there a transformer that can safely supply variable voltage for separately-powered blocks for climbing and descending hills?" No. If there is a modern "transformer" that can, we can't tall, since the manufacturers all keep their designs secret.
"What is wrong with using different posts on the same transformer? The manual to a new Lionel ZW suggests doing just this." Connecting two outputs of a transformer together effectively puts a short circuit across part of the secondary winding. The fault current that flows bypasses the circuit breaker and will not trip it. I don't know what's inside a modern "ZW" and so have no way to know whether Lionel is right about that.
"Why would Lionel recommend it, if it is dangerous?" I don't know; but it wouldn't be the first time that they have recommended dangerous practices.
"I don't understand how to arrange blocks so i can select their power source from whichever transformer outputs I plan to use,..." Use a switch for each block with as many positions as you have trains to run simultaneously. For example, for two trains, use a double-pole-double-throw switch for each block. Wire the center rail of the block to the switch's common terminal. Wire the other two terminals to the two transformer outputs you want to use. Now, if the switch is thrown one way, the block is powered by one transformer control. If it is thrown the other way, it is powered by the other transformer control. If you use switches with a center-off position, you can completely shut off a block with a train that you do not want to run. For more than two train controls, use a multi-position rotary switch or multiple toggle switches for each block.
"...or what a passive voltage-dropping technique is." It can be a fixed resistor, a rheostat, or a string of anti-parallel diode pairs, for example, connected in series with a single transformer output.
"I know about Lionel rheostats, but don't the transformer control knobs do the same thing as rheostats? I am reading about the KW and that seems to be the case. A rheostat creates resistance by winding a wire, and the controller on a KW rolls on a wound wire to receive different levels of resistance, correct? Can't their be a controller that has two controls rolling on the same wire? I'm not a fan of how Lionel rheostats look or feel." The variable secondary winding on a transformer (like a KW) is not a rheostat. It is a low-resistance copper winding. A rheostat is a variable resistor. Connecting together two taps of a rheostat (if you had one with two taps) merely changes the resistance. Connecting together two taps of a transformer winding causes the transformer to try to deliver a very large current into the wire doing the connecting. The transformer or the wiring to the layout may burn up, but the circuit breaker will never trip. The service manual for the KW contains a small-print note warning against doing this. It is the only instance I have ever seen where Lionel admitted that this practice is dangerous."Will a new ZW solve all my problems?" I can answer this if you or someone else can show me a schematic diagram of a new "ZW".
How can I make sure the instantaneous track voltage supplied to two blocks is the same frequency, amplitude, phase, and waveform? Is there a transformer that can safely supply variable voltage for separately-powered blocks for climbing and descending hills?
What is wrong with using different posts on the same transformer? The manual to a new Lionel ZW suggests doing just this. Why would Lionel recommend it, if it is dangerous? (See page 17: http://www.lionel.com/media/servicedocuments/72-2982-250.pdf)
I don't understand how to arrange blocks so i can select their power source from whichever transformer outputs I plan to use, or what a passive voltage-dropping technique is.
I know about Lionel rheostats, but don't the transformer control knobs do the same thing as rheostats? I am reading about the KW and that seems to be the case. A rheostat creates resistance by winding a wire, and the controller on a KW rolls on a wound wire to receive different levels of resistance, correct? Can't their be a controller that has two controls rolling on the same wire? I'm not a fan of how Lionel rheostats look or feel.Will a new ZW solve all my problems?
Do not run a train from a block powered by one transformer to a block powered by another transformer or, worse, from a block powered by one output to a block powered by another output of the same transformer. This can be done safely only if the instantaneous track voltage supplied to the two blocks is the same, that is, the same frequency, amplitude, phase, and waveform. One place this by design will not be true is separately-powered blocks for climbing and descending hills.
Instead, arrange your blocks so that you can select their power source from whichever transformer outputs you plan to use for running trains. Then use that selection ability to keep each train under the control of the same source as it moves around the layout. Do have all the sources in phase, to minimize any damage when you accidently cross a boundary between sources.
Use passive voltage-dropping techniques from a single source to automatically vary the voltage going up and down hills. Avoid running lighted cars with dual pickups in these areas.
Return accessory and turnout-throwing transformers to the same outside-rail common as the track transformer(s). They do not need to be in phase with the track voltage and will work a little better under some circumstances if they are out of phase.
From the looks of them, your transformers are DC power supplies. I don't think they will have enough power to run O gauge engines. I agree with John, buy a KW. Best bang for the buck.
I doubt those "modern" Lionel transformers with the separate control are providing pure sine waves, they use a chopper to modulate the power.
As far as the switches go, the common is indeed track common, so your switch power will have to share a common with track power. BTW, the switches use AC, so there is no +, just the hot terminal from the transformer.
I'd suggest you trade all those little transformers in for a couple of more robust PW transformers. You can pickup used KW transformers pretty cheaply if you do a little shopping, and they'll be a lot easier to live with.
Hello,
I have been doing some reading, and would like to verify my idea would be safe. I primarily run conventional starter engines on my 0-27 track, with O scale 022 switches. I will have two MRC Tech II transformers powering two outer loops with O22 switches allowing the trains to switch. Here are the transformers:18VACI have three of these Lionel 40watt 3 amp 18VACI assume both these transformers provide a traditional sine current, (not broken like modern power supplies) and should not create any problems so long as they are in phase? (I will use a powerstrip to make sure)
Then I have an inner, third loop (also connected to the outer two via O22 switches) but this loop will have graduate trestles. I would like to use three Lionel 6-12885 40 watt, 3 amp transformers (2nd picture) to power this loop (one for incline, one for flat and one for decline - all blocks).
Finally, I have a 6th 40watt transformer that will be used for lights and accessories (including the o22 switches).
My first question is for the 022 constant voltage. I assume the pin is for +, but where will I put the ground? I will not have a "common" ground as I am not using a single ZW for trains and accessories, but rather one 40 watt transformer to power a train, and one 40 watt to power the switch. Can I have two separate transformers providing grounds on the track to supply the switch with a constant ground? If not, where do I connect the dedicated accessory transformer constant ground after connecting the constant + to the O-22 switch?
My second question is for blocks. I would like to experiment with 2 trains on one loop. I have tested the 40watt transformer with two engines and 6 passenger cars on a loop, and it appears to provide sufficient power. I do not notice a reduction when comparing with a new 360 watt ZW. There is no difference to me, so I think I could use these 1 40 watt transformer for two trains on one track. I run primarily starter sets so they are simple and not loaded with electronics. How would I wire a 153 block signal so the two trains don't crash into each other? Will one signal be sufficient on a loop?Thank you very much for any help
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