Re: Minebea 15mm x 15mm DCC question


Nigel Phillips
 

Forgot to add that a) while the input to the decoder is essentially half wave AC with the high frequency control signal overlay, the output to the motor is plain vanilla DC, and b) DC power controllers are built so that the PWM is more pronounced at low speed, blending into continuous DC at high speed. As most modelers use perhaps 60% at most of the output, motors are using PWM all the time. That's why a good DC controller is amost as good as a DCC one for low speed running. One of the reasons why old controllers need to be retired - they are pure voltage output with high start values. Somewhere on the web are oscillographs of DC controller outputs. 

From my initial static test runs of those 15mm Minebea motors they do seem to be relatively rough running Probably why they are so cheap. 

Nigel




On Monday, March 7, 2022, Mike Conder <vulturenest1@...> wrote:
Thanks for the info Nigel. 

Mike Conder

On Mon, Mar 7, 2022 at 8:17 PM Nigel Phillips <nigelp18000@...> wrote:
Hi Dusty,

Modern DC motors are also PWM. Old decoders had too low a frequency, anything built in the past 5-8 years should be compatible with a coreless motor. These motors run pretty slow anyway.

Heat dissipation is an issue with coreless motors, make sure they are well ventilated. Take that rubber sleeve off for starters. Probably best if the motor is held in place with some brass brackets soldered to the cab floor, rather than using (insulating) silicone.

Westside C16? No, unless some metal removal is undertaken. The motor bracket is too high for the new one. I got rid of it.  Easiest way is to lengthen the cab a tad (couple of mm is enough) using a PSC spare. That allows a cosmetic backhead to be used. Doing just that at the moment.

Nigel

On Mon, Mar 7, 2022 at 3:09 PM Dusty via groups.io <Dustburm=q.com@groups.io> wrote:
Are these motors compatible with DCC over an extended period of use? Someone told me at one point in time that coreless motors didn’t like the pulse frequency modulation(?) method of speed control that DCC employs. While these aren't coreless they may have wire brushes that could be affected? I've ordered a couple motors and am curious. Any experiences to share?

Dusty Burman
623 261-8707

--
Mike Conder

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