I have heard that pulse power is bad for coreless motors. The start up voltage on my old MRC Golden Throttle pack is to high, so for the moment I am using my old Troller Autopulse throttle. But being its an automatic pulse throttle, is this a bad idea? I havent used it much and I do notice the motor runs more noisly on it. I am watching for one of the later MRC throttles with better low voltage control but still with the metal housing and not the plastic case stuff they have now. A controlmaster 20 would be overkill. Would one of the MRC Controlmaster V throttles do ok with low voltage control. The motor is installed in an old PFM brass C&S Mogul, the old open frame didnt have good low speed performance and couldnt maintain a constant speed. Thanks Mike
Low frequency pulse power probably would be bad for a coreless motor. The armature windings don’t have the iron core to sink the heat, so they could get hot pretty quickly. I always run my coreless powered engines on filtered DC, since the pulse setting causes strange running behaviors and a lot of noise.
If you can’t avoid pulsing power, it may be possible to put a small filter (like a capacitor) on the motor. You’d have to look up a circuit online, but I’m guessing it would be fairly simple to put one together.
Any pulse power is bad for coreless motors because it causes them to overheat very quickly. You could add an electrolytic capacitor across the output terminals of the Troller and that would smooth out some of the pulses, but you’d be much better off purchasing a new power pack.
I will just hunt up a better older MRC pack that I can turn off the pulse power. I am watching one now that I may bid on depending on what happens. I dont care for the newer black plastic case MRC throttles, they just feel cheap. I like the older metal ones, but with the coreless motor I need one of the later models with good low speed control without the use of pulse power. Mike
If you ever put an electrolytic capacitor across the output of a power pack, you better make sure it is a bipolar electrolytic that is not polarity sensitive. Otherwise, with the incorrect polarity on a standard polarized capacitor, the cap will go poof. Been there, done that, have the T shirt.
To the naysayers, put a standard 250ufd capacitor on 12 volts DC and reverse the polarity for a couple minutes. Let us know the results.
Rich
ABsolutely true, we used to scare people in college by doing it on purpose.
If you can access the inside of the power pack you can install the capacitor BEFORE the direction switch, in which case an ordinary electrolytic is fine, it will always see the same polarity.
–Randy
Yes, I sure goofed that one up. I should have written “bi-polar” electrolytic capacitor.
The coreless motor draws too little current for a rheostat to work properly (your Throttlepack uses a rheostat). If you can find one, any of the older MRC Controlmaster series should meet with your preferences. All have a transistor throttle of some type. I have also found the Tech 2 and newer MRC Tech series to be very reliable and dependable despite the semi-sealed plastic case [V].
Any of the MRC transistor throttles (Controlmaster and Tech series) with pulse power have “softer” pulses than your Troller does. If the pulse frequency or rate is adjustable, so much the better - set it at the highest setting for your coreless motor.
You can also build a very cheap and simple transistor throttle to hang off the AC or DC outputs (use a full wave rectifier in front of the throttle circuit to use on AC terminals) of any of your existing power packs. This will provide good voltage control to all your motors. Circuits can be found by searching the web on “DC throttles”.
I use a Tech 2 2500 (bought used at a pawn shop in Alaska) and a home-made handheld transistor throttle as my 2 primary controllers on my layout. My HOn3 line has an FED 2-6-0 with the Roundbell conversion - features a 24V coreless motor.
my thoughts, your choices
Fred W