This one page showing the expected waveform was too big to attach so I've put it here as a JPG: http://www.autoartisans.com/MotorDrives/PulsePower3.jpg
I agree it's a PWM motor controller but without a filter on the output. (well actually the motor inductance acts as a filter of course) However I've never seen a circuit were the DC component as a varying voltage is summed with the PWM component. I built a little DC motor driver several decades ago using a 555 timer and driver transistor. One of the major differences is 15kHz instead of 60 Hz. But I've never tried that on an HO train to see if it was adequate or if the load of extra cars resulted in jerky starts. I still have one around somewhere. Maybe I'll post a picture. John > -----Original Message----- > From: Gregg Eshelman via Emc-users [mailto:emc-users@lists.sourceforge.net] > Sent: April-10-22 2:29 AM > To: Enhanced Machine Controller (EMC) > Cc: Gregg Eshelman > Subject: Re: [Emc-users] Controlling DC motors. > > In other words the person who designed that created a pulse width modulation > motor controller without calling it that. > > > On Saturday, April 9, 2022, 08:18:17 PM MDT, John Dammeyer > <jo...@autoartisans.com> wrote: > > > Really nothing to do with LCNC or even automation.� > > I've been cleaning out old shelves and I have piles of Popular Electronics > Magazines.� This one from December 1965 (yes, almost 57 > years old) has an article on how to improve model trains so they start slowly > or crawl rather than lurching forward requiring backing > off the speed control. > > They call it pulse power.� Using only transistors and diodes the article > describes a method of creating narrow pulses superimposed on > a varying DC voltage.� One knob controls the width of the 12V pulses and the > other the amplitude of the DC mixed with the pulses.� > The pulses are 60Hz. > > Now we just buy stuff like that for way less than what the transistors would > cost.� Things have come a long way. > > Just thought I'd share. > John > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users
100-0051-PWM-DRV.pdf
Description: Adobe PDF document
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