Can I use an LCRU2 to Run a DC Motor

I forgot to mention that the GP9 has a Pullmor motor.

Don't think it will work. Lionel made a LCRU for DC can motor locos.

THe problem is that the rectifier on the AC output will always have + DC on the rectifier + lead and vice versa for the negative lead. So no direction control. The rectifier needs to be infront of the TRIACS. Early DC Motor Controllers used the same TRIACs on the LCRU2, but the rectifier was on the board as and input to the Triac H bridge. G

A LCRU can run a DC motor if wired like this.
I think a LCRU2 will work also.

Basically you put a diode where the field would be and the Can motor goes where the brushes would go.



Ignore (bypass)the RF choke in the diagram.

Carl

Carl,

Thanks, for the diagram. I'm not an expert in electronics so bare with what might seem obvious.

What size diode should I use?

Will this allow forward and reverse direction control?

Thanks
Phil

Phil,

Radio Shack has a 6 amp diodes that will work.
part number 276-1661

Yes it will reverse.

The only caveat is that the motor will use halfwave DC but I have never had an issue with that.

Carl

Carl,

So if I understand halfwave DC there should be no problem hooking the Railsound 2.5 broad to the DC motor instead of using the mechanical switch correct?

Also on the Tuveson website it is mentioned that halfwave boards have a problem with DC voltage offset and legacy sound boards cannot be use on the same track. Is that the case with the way suggested?

I don’s half any legacy engines now so it’s not a problem just want to know if it will be a problem down the road.

Again, Thanks for all your help.

Make sure your 100uh choke can handle the maximum current, many of those only handle milliamps.

Carl, Your words don't match your picture. Yellow and Blue are normally to the armature brushes. Green to the field.

Your diagram replace the AC motor with a diode, and use the field to the DC motor going to ground.

I still think putting a full rectifier infront of the triacs is best, but that requires board modification. G

Yes the diode goes where the the brushes would go. Ooops.

The Triacs reverse the polarity of the diode which is in series with the can motor through the board wiring.

It has been a long time since I did this drawing and I was going from memory.
It is so simple to do why mess with the board? It did the job for my needs.

This was done along time ago before any driverboards were available like there are now.

The choke was for two rail operation to improve the Signal strengh but would not be needed on a 3 rail layout.

Carl

Carl, This does work I agree. The triacs reverse the current flow through the armature brush leads, while maintaining current flow in the same direction through the field windings (green lead).

Performance and safety are the only issues. Half wave drive for the motor vice full DC. Also an undetected short on the diode would revert to pure AC to the DC motor possibly damaging it if undetected. The full wave rectification before the Triacs would be safer then a single diode, but would require board modification to make it work. G

Wow! I haven't done this for years! It works great, as I have used Carls procedure to convert a number of small engines before small drivers were available, and when LCRU's were available cheaply.
Built a couple of his boards off the schematics, too. Great projects if you have lots of time and not a lot of bucks.

Carl,

I final found the time to try this out. But I seem to have a problem, I hooked up the wires per the diagram with the exception of hooking them up to the DC motors. When I put a meter on the black and green wires, I am getting full 18V AC little or no DC. The Railsounds, directional lighting works fine so I know the signal is getting to the board. Any ideas of what could be wrong or things I could check out? I did try 2 different diodes which I just brought new.

Thanks for any help.

Phil

Meter won't work. Need a load to draw current through the TRIAC circuit for it to work. Take a small DC motor and wire it in and then test the board. G

Thanks GGG,

I tried a small dc race car and it ran in forward and reverse. Not sure I understand how, I am just learning this stuff. I'll finish the wiring to the engine tomorrow and see how it works.

Thanks Again,
Phil

Phil, a meter doesn't provide any significant load on a circuit it is used to measure. I think Carl's site has a better diagram of the H bridge arrangment of the TRIACs, but current flow is need throught them to operate the way they are connected.

To test your unit as an AC LCRU, you need two loads. Once to represent the motor and one to represent the field. Light bulbs work. G

When I used LED's for lighting on the R2LC or LCRU, I have to put a load resistor in just to get the lights to work. 1K has always done it for me, don't need much.

All Done and works fine, I now have a Williams NYC E7 with TMCC, RailSounds, Mars Light and Electric Couplers, it runs and looks great.

I want to thank everyone for their input on this.

Phil

I've been using Carl's wiring to run DC motors with a LCRU for close to 10 years now.
Suddenly i've run into a problem: i've added an ERR Sound Commander to the circuit in two identical locos (GG1's) and have developed a problem in only ONE of them. In one installation everything works (start-up sounds, horn, bell; directional lighting; and engine runs perfectly). However in the second installation with the Sound Commander connected i get ONLY start-up sounds (NO horn or bell) and the engine will NOT move NOR change directional lighting -- disconnect the Sound Commander and the engine runs as it should.
Any ideas before i call ERR tomorrow??
jack