View single post by Si.
 Posted: Sun May 31st, 2015 01:16 am
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Si.



Joined: Thu Feb 23rd, 2012
Location: London
Posts: 5940
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Hi Kent.

Thanks for mentioning the potential issue with micro-motors.

Looking at the original construction article the other day; I was quite surprised to see that a 16-20 Volt A.C. transformer was recommended for the throttle.
Going on to say, that 25 Volt 'peaks' can occur.
There is however a 'maximum-speed' preset in the design, for adjustment.

Since the typical micro-motor user, is I guess, interested in 'scale-speed' rather than 'max-speed'; I figure the average micro-motor often doesn't get cranked-up beyond 1/2-way on a typical throttle.

Here's a link to a short P.D.F that talks about this & has a schematic for a simple non-P.W.M 'current-limited' throttle.

Micro-motor control & current-limited throttle schematic.

As is pointed out, coreless micro-motors are not great at disipating HEAT. :shocked:

- - - - - - -

Here's the track-side of the throttle.
There is a P.C.B layout in the article.
I seem to have changed it about a bit; to bring all the terminals out at one end.

It's so simple though, If I were making it today, I wouldn't bother with a P.C.B; and would use a 'tag-board' instead.



I actualy remember etching the nice wooden-floor in front of the sink, with the ferric-chloride !!
I seem to also remember, that Pops was a tad peeved about this ! :f:

Cheers.

Si.

:moose:




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