I'm converting my layout to Wangrow's System One. On page 2-33 of their manual, under "Decoders", it says

"Do not use with coreless motors"

No explanation why and no references anywhere else.

Obvious question - if you've got locos with coreless motors just what are you supposed to do. The locos I have are whitemetal kits and I don't think it would be possible to change the motors.

Are there decoders that work with coreless motors?

-- Graham Saint (amgray@matra.com.au), April 09, 1999

Answers

Coreless motors typically have low internal inductance and resistance. Typical DCC decoders cannot safely supply the peak currents that they will demand. If you can't repower with a more modern can type motor you have 3 options.

1. Measure the stall amps at some fixed Vdc. Divide by the stall volts to calculate motor resistance. Add a discrete resistor in series with the motor leads to get ~7 ohms total. This will allow you to use a decoder rated for 2 amps peak. (14 volts / 7 ohms = 2 amps) Resistor will get hot, so use a 3 or 5 watt power resistor.

2. Measure motor resistance and calculate peak amps as above. Find and install a decoder rated for those peak amps.

With either 1 or 2, program the decoder to operate at the highest possible PWM frequency.

3. Stay with DC.

-- Don Vollrath (dvollrath@magnetek.com), April 13, 1999.

Graham,

Coreless motors are handled quite well by the Back-EMF decoders available. The ZIMO MX61/N and the Lenz LE130 both will do excellent work with coreless motors. Nice thing is both of these are advanced decoders. The ZIMO has a 16KHZ PWM (adjustable) and excellent overload protection. The Lenz has a nice funciton interface and good overload protection - and a mistake free warranty. Both decoders are available from TTX, dicounts on quanities of 4 or more, and are in the low to mid $ 40.00 each. I have some of each - use them almost exclusively, and the Back-EMF features make for superb low speed characteristics.

-- Ed McCamey (emccamey@cheerful.com), April 15, 1999.

Try looking at a choke I beleive a 0.1 micro henry is right. To confirm sen a email to maxon or the supplier of the motor.

One of my customers is doing this with earlier decoders and has quite a few hours up. Now installing a soundtraxx decoder with a coreless motor.

-- GarySS (mrc@zip.com.au), March 06, 2002.

Try looking at a choke I beleive a 0.1 micro henry is right. To confirm send a email to maxon or the supplier of the motor.

One of my customers is doing this with earlier decoders and has quite a few hours up. Now installing a soundtraxx decoder with a coreless motor.

-- GarySS (mrc@zip.com.au), March 06, 2002.

Lenz are due to bring out a couple of new decoders designed for 'Silent Drive' and coreless motors. They are LE0511A (upto 0.5 Amp)and LE1014A (upto 1 Amp). The item numbers might be slightly different in the USA (I live in the UK). I was told that they should be available 'within the next month or so'. Also; have a look at the LE080XS, they're not available on this side of the pond now, but I wonder whether you might still be able to get them. They're okay upto 0.8Amp, which is pretty big for a coreless motor!

-- Steph Dale (steph.dale@talk21.com), April 12, 2002.