06-20-2009, 08:13 AM
nomad Wrote:Well, the Powercab gasped it's last breath and was consigned to the junk box.
For walk around throttles, I am looking into these.
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Loren
Loren
PWM (Pulse Width Modulation) is used by all DCC decoders to power the motors because of its efficiency (not much heat to dissipate). Unfortunately, PWM depends on the hysteresis (coasting ability between pulses) of the motor to work. If 60Hz PWM is used, some of the very high quality motors - coreless motors specifically - don't have the mass to coast sufficiently between pulses at very low speeds. These motors will overheat on 60Hz PWM. And being relatively expensive motors - generally $40 and up - the loss is even worse. Newer DCC decoders use a much faster pulse rate, typically in the neighborhood of 1KHz or higher, to avoid overheating of low mass motors and to get rid of the growling noise caused by low freq PWM. Some DCC decoder manufacturers even call this "Silent Drive".
The throttle you linked to operates at 60Hz, with no ability to modify the frequency. With most motors, this will work very well. With coreless motors and a few very good small can (think N and Z size) motors - not so good. Just a word of caution. Check your locomotive motors for overheating after operating a while at slow switching speeds. If it's too hot to touch, it's too hot.
my thoughts, your choices
Fred Wright