L2RU BOARD DRIVING DC MOTOR

Nope, but he has.  Why not try it. G

Carl Tuveson is a pretty savvy guy when it comes to using TMCC stuff, if he says it works, it probably does.  I'm sure he tested those configurations before posting them.  I'd use a 3A diode for anything O-gauge sized.

Thanks John,  was a little timid about taking the chance since a common e-unit switches the leads to the brushes in order to reverse the motor and leaves the phasing of the field hard wired with one side permanently attached to chassis ground.  I don't doubt Carl has it worked out for a LCRU. More info on his site than any other single site I have found.   I just hope the L2RU is the same except for the plugs. I tried to draw a schematic of it to compare with the LCRU schematic on Carls site, but cannot see where all the traces end up.  Guess a 10A chinese diode is a match for a 3A IR diode. I usually just keep twos and tens in my parts bins.  I'll add fuses in a couple places when I test it on the bench.  By chance do you know the frequency of the PWM on the L2RU/LCRU boards. Or any other TMCC boards for that matter. Coreless motors like it high 10k hz. or higher.  Thanks again,      John

The LCRU has triacs and thus has a 120hz frequency of motor pulses, I'm assuming they fire on both halves of the AC waveform.

FWIW, I found his diagram a bit odd as well, but I've never really traced out the operation of the LCRU, so I took his word for it.  I'd probably wire one up on the bench with a cheap DC motor and test it before turning it loose on something more expensive.

Just substitute the pink to AC hot on the LCRU for the Red on the LCRU-2 

That should work.

You are wiring the diode in place of the brushes which is in series with the can motor therefore when the brush polarity is flipped by the triacs the motor runs in reverse.  

 That provides a half wave DC to the motor. I do not know if your coreless motors will like that?

Carl 

So, sounds like he'll have 60hz pulses with this scheme.

FWIW i followed Carl's wiring instructions about 10+ years ago with LCRU's and the basic Mabuchi DC motors. They work fine.

YEAH, or how to make a coreless motor speak like a pullmor motor.  This was one of my concerns and why I asked about the PWM pulse frequency.  The DCC manufacturers had this problem and addressed it with higher pulse frequencies. Carl, thanks for chiming in.  I have several Maxon motors and they are so good at slow speeds on DC and about half again more powerful than a similar size iron core motor. I'm sure both of you know the benefits.  Have either of you tried capacitance, chokes or both to smooth out low frequency pulse power enough that coreless motors might tolerate the low pulse frequency?   One possible problem I see is that enough capacitance to make the motors happy might create such a momentum effect as to make the loco unresponsive to throttle input.  Guess this begs the question, What's the pulse frequency of Legacy and DCS ?

Capacitors don't do squat to smooth out a PWM signal, at least they didn't for me.

I haven't measured the PWM drive of the newer command boards, but I suspect they're higher than 60hz.  OTOH, when I did the Super-Chuffer, I had the PWM set at a high rate, around 20khz, and it didn't work well at all with smoke fan motors.  When I dropped it to less than 1khz, it worked much better.

Just finished testing it on the bench and standard iron core motors work fine however when I hooked up the coreless Maxon one of the 200 ohm resistors next to the opto couplers got hot enough to burn off some of the paint. I let it cool down and then hooked up an iron core motor again, no problem.  Not only did the coreless motor not like the tmcc board, the board did not like running the coreless motor. At least in a half wave mode. Guess that answers one question.   I am going to try something a little different before I give up on the coreless motors though. I'll write about it if it works.

I traced these long ago and Carl site is very helpful.  LCRU 2 was primarily and upgrade in having connectors instead of just wires, plus programming via software vice hardwire selection.  There also is an LCRU with no motor control section.  It was how Lionel transitioned to DC motor in a TMCC environment.  It drove a DCDR with the phasing info via 4 pin.  You could try to mimic that one and use the LCRU to drive a DCDR which is designed for DC motors.

While this is all very nice since you have them, you are dealing with pretty old tech and components, and NO cruise control.  It may be worth your effort to just use ERR Cruise CDR.  G

Have to go with GGG here, I'd forget about the LCRU and use the ERR Cruise Commander or for smaller stuff, the Cruise Commander Lite.

Not sure the cruise boards will work with a coreless motor as the depend on Back EMF?

That's a really good point Carl, I didn't think of that!

I see a motor swap in the near future.

Wow I love the idea of what you're doing.  I would like to see the coreless motor installed in the Hudson, some pics and especially a video of it running.  Thanks for sharing!  Good luck on your project, please post some pics / video when it's completed!  -Ted

Ted It may not happen as per GGG, John and Carl's advice and opinions. I think the biggest obstacle is the low frequency PWM on the TMCC boards. I knew when I started that coreless motors are notorious for not getting along with PWM.  Even with a DCDR motor driver board the coreless motors are not going to be happy.  I have quite a collection of Flyer and may use my coreless motors to repower my favorite Flyer locos and use DCC as the coreless problem has been mostly worked out by the DCC manufactures.  I still have a couple of things I want to try before I pack it in.