Which 3-rail trains will run on straight DC?

The 4-4-2 models made by Lionel will, the forward only postwar and prewar engines from Lionel and Marx will, and the DC only MPC era Lionel will. Kusan Locomotives do, I think, as did old Atlas O

Well, be careful, the OP asked about using an HO-style DC  transformer. I feel pretty safe saying that ANY O-gauge loco draws more current than an HO loco. So, while the O-gauge loco may indeed run on DC, an HO power pack may not be hefty enough to make it happen, especially with the older series motor stuff. 

PLCProf posted:

Well, be careful, the OP asked about using an HO-style DC  transformer. I feel pretty safe saying that ANY O-gauge loco draws more current than an HO loco. So, while the O-gauge loco may indeed run on DC, an HO power pack may not be hefty enough to make it happen, especially with the older series motor stuff. 

Sorry, I just meant  DC-style.  I realize that O scale needs more Wattage, but they do make powerful DC transformers, even for use with HO layouts.  I believe o-scale 2-railers use them, if they don't have DCC

Does any currently-produced Lionel run on straight dc?

Martin H posted:

I'm just curious.  How many, if any, 3-rail trains will run on a ho-style DC transformer?  I am  under the impression that PS3 trains from MTH will.  How about PS2 or PS1 trains?  Will atlasO locos run with a DC transformer?  

All 3-rail trains have DC motors in them, right?

The older 3 rail locos use series wound universal motors; these function as well on DC as AC.

Bogie

Yes, "O-scalers" tend to use DC power, and therefore DC power sources. 

There's nothing "HO" about it. HO descends directly from O-scale technology (the 2-rail, DC kind) - it was just smaller. 

I think that some of the newer MTH 3-rail equipment will adjust to whichever power source you put on the track, but most has never done that, MTH or not. DC into AC electronics = dead. An AC motor itself would not be bothered, as it is a universal motor, anyway, as mentioned above; a DC can motor is just that: DC; AC will damage it.

The best way to find out is to read the specs on the box, or elsewhere. 

PS/2 runs on DC, though you do have to have the polarity correct.  For 2-rail PS/2 upgrades, I put in a polarity reversing switch.

I would not run any Locomotives on DC that are designed to run on AC . The sound units in those locos are triggered by shot of DC that rides on the AC sign wave. Any DC put into the tracks and the sound units will work continuously. Now if you gutted those engines and wired direct to the pickups the motors and  can motors will work fine on DC.

Do all MTH PS2 locomotives run on DC? I thought that ability to run on DC was something MTH added somewhere along the way. 

If you do intend to use a HO power pack, PLCPROF is correct in what he is saying. Especially, if you are using a locomotive with command control and sounds.

Here is a quick video of a MTH PS2 3/2 locomotive. Although it is in 2 rail mode for demonstration purposes, it doesn't matter as the electronics don't care how many rails there are. Notice in the end of the video you can see that the power pack is turned up to about 80% of it's power.

What I don't like about the MTH locomotives in pure DC mode is you can't ring the bell or blow the whistle. I wonder if the DCS Commander would allow the whistle and bell to used in pure DC mode?

In Atlas DCC locomotives you blow the whistle in pure DC mode by flipping the direction switch while the locomotive is in motion. Which is actually kind of fun. 

I have at one time or another run just about every engine I have ( MTH, Atlas, Weaver, and Lionel 3 rail)  with an HO power pack.  They run ok but if you were running several locos in a consist (lash-up) it may not be enough power.  Or, if you are running a train of lighted passenger cars they too might draw too much power.  I have even run some G scale locos with an HO power pack.

Rick

I ran my Weaver 4-6-0 using a Troller Transamp 1, DC volts.  Of course all I had hooked up was the DC can motor, ran pretty good too.

That's the good thing about these engines with can motors, if the electronics dies you can always gut it and run the DC can motor from a DC power pack.  It's all the "bling" that we have come to expect in our models that need the helping hand of command control.

Be aware that during the modern era, Lionel did issue warnings not to use DC power with some of their trains.
Most prewar and postwar Lionel trains could be run on DC, provided the horn/whistle was disconnected. Items operated by AC introduced vibrations, like cattle cars, rotating radar antenna, saw mill, etc. will not work.

C W Burfle posted:

Be aware that during the modern era, Lionel did issue warnings not to use DC power with some of their trains.

I would like to know more about which ones.

The engines with the 103/107 electronic reverse units run perfectly on DC.

I wouldn't try it with any TMCC equipment.

I have a Marx little red Switcher that is A DC engine 

Since the TMCC RCDR uses triacs to power the motor, and they need AC power, they probably won't run on DC.  Lionel cautions you against DC in both the TMCC and Legacy manuals.

For Legacy...

Power your locomotive with an alternating-current (AC) transformer only. Powering your
locomotive with a direct-current (DC) transformer, or in excess of 19 volts AC, may result
in damage to sensitive electronic components.

For TMCC...

Do not power your locomotive with a direct-current (DC) transformer. Damage to
sensitive electronic components may occur.

I have a Williams legacy engine that has a feature that shuts off power in the engine if the amperage (wattage) is too low.  Some others may do that too.  The engine makes a quick movement, then stops completely.  Use a larger capacity transformer and it works fine.

Your nice engines with all the electronics, if you get ones with failed parts, odds are you can gut the electronics and use just the can motor for pure DC operation.

I can see anything with Triacs not working with DC, and would be curious how common Triac motor drivers are as opposed to ones using transistors or mosfets.  Are they used for the open frame motors, even though those could be run from DC?  

As for TMCC engines, the track signal requires AC as a carrier, so anything TMCC or Legacy technically needs to be powered from AC.  I think one could get around that if they really wanted to, but that is a whole other subject. Aside from a triac motor driver, however, I do not know what could be actually damaged in TMCC or Legacy from applying DC power.  

As others have mentioned, anything that depends on the DC offset for sound control will be a problem, even if the engine its self would run on DC.  

When it comes down to it, pretty much all O gauge trains can be run on DC, if you want to make some modifications, and the same is true of running "DC only" ones on AC.  The main limiting factor here is if you want to keep all the original electronics working correctly.  

For those more knowledgeable on these things, without modification do typical post war engines run on DC?  I'm not sure why they would not, but I don't know if maybe the e-unit has to be wired differently or some such.  I know there is some talk of overheating the e-units on DC power, but not familiar with what causes that either.  

From time to time I've kicked around the idea of using DC power, mostly due to high current DC switching power supplies being so much cheaper than AC transformers, but in the end the cost savings hasn't really worked out with the costs of getting all the trains working correctly.  I still plan on using pretty much free computer power supplies to power lighting and accessories.  

JGL

The Lionel ACDR uses triacs, and the ERR AC Commander uses the Q4008L4 triac, so I'd say most TMCC AC stuff uses triacs.  The older LCRU also has triacs.

Anything with a circuit board and can motors will run just as well off DC as AC.

This is because the AC is rectified to DC before it does anything useful. Polarity is not an issue because the rectifier will correct it.

That's clearly wrong Matt, let us know how you make out with your Lionel Legacy locomotive and DC.  Let's see, circuit board and can motor?  Check!  Runs on DC?  NOPE!

Matt Kirsch posted:

Anything with a circuit board and can motors will run just as well off DC as AC.

This is because the AC is rectified to DC before it does anything useful. Polarity is not an issue because the rectifier will correct it.

This, as GRJ says, is clearly not the case.  

The first thing is with any TMCC or legacy engine, the signal requires a low frequency carrier wave, The 60 cycle of standard US power works fine for this.  I think you could get around this in a few creative ways, but haven't proven that yet.  

The second thing is that polarity does tend to matter on many boards.  The designers took the cheap/easy way out and used a single diode for half wave rectification.  A full wave bridge will allow dc to pass through from either polarity, but a single diode rectifier will only allow power to flow from one direction.  It won't cause damage with polarity reversed, but it won't work.  

Next you have the triacs.  Anything that uses triacs, or SCR's, in the electronics will not work on pure DC power.  Triacs are great for controlling high current loads like motors and smoke units, but they have one big problem.  They can not be turned off.  Triacs depend on the power being supplied to them being shut off before they stop conducting.  With AC this is not a problem, because the power shuts off 60 times a second as the wave crosses zero.  With DC power supplied, once a triac is turned on, it will remain on.  This is a problem for things like the smoke or light controls on a R2LC, and can actually cause damage if triacs are used in the motor driver H-Bridge.  

In theory, you could use pulsed DC to remove the risk of damage, but the speed control or smoke volume adjustments would be off from how they were designed, as they would effectively be receiving a PWM signal rather than a portion of the AC sine wave with different amounts of electrical energy.  This is something I might play with some day, using a high current transistor or Mosfet to cycle DC power off at something like 60 cycles, and see if TMCC engines could be made to run on such power.  Again, a neat project, but just running AC is probably a lot simpler unless there is a specific reason for wanting to use DC.  

Now, If someone took the time, I bet each triac in use could be replaced with a transistor or mosfet that would do the job on DC power, but I'm unsure exactly what would be involved.  I've been kicking around trying to design a direct drop in replacement for the R2LC board that worked on the 2.4GHZ band,removing the sometimes problematic track signal from the equation,  and would probably use DC compatible components if this ever comes about.  I think it would be neat to have full TMCC control available for battery power locos and such. 

JGL

"Do not power your locomotive with a direct-current (DC) transformer. Damage to
sensitive electronic components may occur."

Another example of an oxymoron.

Alex

Why run on DC when your Lionel and MTH run much better on AC? If your running Ho then by all means use DC. 

Isn't the whistle going to blow  continuously  if the engine slips  into conventional mode  with DC current  ?   

The whistle is the least of your problems if you're talking about TMCC or Legacy.

I always like questions like this they have sooo many variables that the answers are all over the board.

If you strip away all electronics any train with a universal motor or a DC motor can run on DC Power.  But a DC motor could not run on AC.

You would have direction control with DC motor by reversing polarity to the track, but you would not have direction control with universal motor with out a wire switch on the engine.  When you reverse polarity on track, both armature AND field polarity change and it goes in the same direction. SO engine would need mods to work with polarity switch for reversing direction.

Conventional sounds would be issue.  The constant DC would trigger sounds constantly.

Most e-unit could handle DC, but some advance Command systems may not.

I am curious why folks say TRIAC is the issue?  A TRIAC can handle current in either direction which is why it is great for AC, but they work with DC too.  The DCDR uses Triacs, but has a rectifier since the motors need DC. 

FET versus Triac have to do with how they turn on and off, efficiency and some other factors.  So PWM cruise is best with FET for DC motor.

If your talking about a full command controlled engine, then MTH is the only one that can handle AC and DC in conventional and DCS (no sound control in conventional).  PS-3 is the only one that is not polarity sensitive to DCS signal and can do DCC also.

G

Plastic Lionel K4 from 1980, since DC only doesn't have any reverse unit.

Ingeniero No1 posted:

"Do not power your locomotive with a direct-current (DC) transformer. Damage to
sensitive electronic components may occur."

Another example of an oxymoron.

This is pretty funny, actually, but I think it will go over the heads of most folks, as your average person considers any device that converts wall outlet, line voltage to track level voltage to be a transformer.  Same with all those little wall packs and phone chargers.  Most people don't consider the actual part called a transformer and the fact that they only work with AC.  

david1 posted:

Why run on DC when your Lionel and MTH run much better on AC? If your running Ho then by all means use DC. 

There are three possibilities that I can think of.  One is to run from battery power.   the second is if someone lives somewhere that 60 cycle, 120V power is not available.  It is much easier to build/but a DC power supply than to convert 50Hz 240v into 60HZ 120v.  The last is that DC power supplies are insanely less expensive than similar output transformers.  A typical budget level, $15 computer power supply delivers over 15 amps on the 12V rail.  and over 30 amps on the 5V rail, and typically has quite impressive spike and short protection.  

GGG posted:

 

I am curious why folks say TRIAC is the issue?  A TRIAC can handle current in either direction which is why it is great for AC, but they work with DC too.  The DCDR uses Triacs, but has a rectifier since the motors need DC. 

FET versus Triac have to do with how they turn on and off, efficiency and some other factors.  So PWM cruise is best with FET for DC motor.

While there is no harm going to come from running DC through a Triac, they are pretty much useless for sourcing DC current.  Triacs can be turned on at any time with a nice low current on the gate, but once they are triggered they remain turned on until power is removed from the supplying anode.  They do not care what is done on the gate once current starts flowing between the anodes (t1,t2)  This works fine in AC as current stops flowing 60 times a second as the sine wave crosses 0 volts.  It is also why zero crossing circuits are needed in many applications where triacs are used to apply PWM to an AC current.  In use with DC, you would need another device to shut off the power to the triac, and I can't think of any reason someone would still use a triac in addition to whatever component would be needed to feed the triac.  

Triacs are probably the simplest part to use for controlling AC, but are pretty much useless for controlling DC.  Fets on the other hand are a bit more complex to work with, many requiring gate voltages well above the voltage being sourced.  You also need a pair of them to conduct AC, one for each half of the sine wave.  Mosfets tend to be preferred over BJT transistors these days because they are voltage, rather than current controlled, so you don't need a series of transistors to step up the current, nor have to deal with the heat caused by each of those transistors.  I still like transistors, but trying to stuff 4 2n3055's and all the heat sink into a boiler is not going to happen.  

The problem I see with any motor drivers in trains with triacs is that once current starts flowing through one, it will not stop.  if a second triac is then turned on to source current in an opposite direction, the two will short.  I'm unsure if this is a possible condition on the lionel drivers that use them, or if the setup for a universal motor precludes the possibility of a direct short between two triacs.  

JGL

IMHO, many of the folks posting here are way over thinking the question.

You can turn the triac on with DC, but you can never turn it off.

C W Burfle posted:

IMHO, many of the folks posting here are way over thinking the question.

It wouldn't be any fun if we didn't get to over-think an issue now and again.

The AC vs DC argument is almost as old as are model trains. My layout contained both AC and DC power options from day one. Early universal motor locos will run better on DC, but have to be modified to obtain direction control. Most later DC can motor locos will be OK with DC, but tend to run somewhat slower for a given conventional mode throttle setting. Sound in this mode generally depended on the polarity of the applied DC. When a manufacturer specifically warns against DC, I would heed the warning.

I have been running the small bump & go can motor trolleys from Lionel, MTH, & Industrial Rail with HO transformers for many years.  But just the trolleys, some lighting, and DC only equipment (like the Atlas turntable motor) .   They run very well at slow speed for a long time, but over loading with say several lights added to the pack, will make the transformer cut out.  It must cool before coming back on.  Watch your amperage draw before using, and on DC equipment only.  I wont run anything else in three rail on a DC HO power source.

Dennis

JLG and John, Both you guys made statements that TRAIC "can't" be used with DC.  They are used with DCDR to drive the DC Motor engine.  You need to chose your wording better.   They are not the best solution obviously, and I stated that in my response.  Look at a DCDR.  It is exactly the same as the ACDR except it has the bridge rectifier to convert AC to DC.

JLG you asked about TRIAC versus Fet, I gave you an answer, then you constructed this long answer about them?  Did you stay at a Holiday inn last night?

GGG, you don't happen to have a schematic of the DCDR hanging about?  I'd really like to see how they managed to use a Triac to regulate DC power.  

JGL

Well, how about the other obvious answer - LionChief and LionChief+ are designed to run off of AC/DC.    THUNDERSTRUCK

GGG posted:

JLG and John, Both you guys made statements that TRAIC "can't" be used with DC.  They are used with DCDR to drive the DC Motor engine.  You need to chose your wording better.   They are not the best solution obviously, and I stated that in my response.  Look at a DCDR.  It is exactly the same as the ACDR except it has the bridge rectifier to convert AC to DC.

The DCDR depends on the fact that the full wave rectified AC goes to zero every half cycle to allow the triac to turn off as they used the unfiltered rectified current in the circuit.  So yes, it "can" be used with DC under specific circumstances, as long as you can wait for the DC to drop to zero to turn it off.  It's really running with AC with a DC BIAS, a true DC voltage is unusable with a triac.

We're really arguing about how many angels can dance on the head of a pin here.

Moonman posted:

Well, how about the other obvious answer - LionChief and LionChief+ are designed to run off of AC/DC.    THUNDERSTRUCK

I believe the LC uses FET drivers for motor control.

After finally figuring out how the DCDR actually works... Sure, if you want to call a voltage that rises to 25.5V and drops back to 0, 120 times a second giving you about 18V RMS flowing through the triac DC.  I still choose to call power that alternates between some value and zero at a regular interval AC.  I suppose it would be better described as pulsing current rather than AC or DC, but in any case you're humped if you try to use a DCDR with filtered DC track power.  And, as the DCDR is just a simple H-bridge, you'll probably smoke the triacs if you cycle from forward to reverse,  as both halves of the H-bridge remained turned on, producing a direct short across the power input.  I'm unsure if the r4lc or whatever controls the dcdr uses zero-crossing detection, if so, it may know better than to flip the H-bridge before the voltage drops to 0.   I have to wonder if Big L just got a really, really, good deal on a couple million BTA08's and designed the motor driver around them.  

As noted in an earlier post, one could still use DC with triacs as well, if the DC source was pulsed even at say a 99.9% duty cycle. 

As an additional thing just to confuse it up a bit more, there are also Gate turn-off thyristors, or GTO Triacs, these CAN be turned off from the gate, but require a negative  DC voltage source to do so, making them reasonably more complex to work with.  They are most commonly used in DC to AC power inverters.  

JGL