DC Motor with DPDT and Speed Control - Help Needed

Thread Starter

Deleted member 966102

Joined Dec 31, 1969
0
I'm working on a machine that I need to help with my business. Essentially, I am looking for something that works similar to a VHS Rewinder / Fast Forwarder that has variable speed. See this video on Youtube for what I am trying to accomplish.

What I have been looking into is having two DC motors. Each engaged separately via a single DPDT toggle One rotates clockwise when engaged, the other counterclockwise when engaged. I think I have that part down, but I would like to have one speed controller that effects whichever motor is engaged at that time.

I was thinking that perhaps the speed controller would go between the power supply and the DPDT toggle, that way whichever motor is engaged would be affected by the controller. Not sure if this is correct or not.

I've love some help/advise on this. Maybe even a circuitry diagram if anyone feels so inclined. I'm new to this so trying to research this as I go. Thanks!
 

Reloadron

Joined Jan 15, 2015
7,523
No mention of motor voltage and current? Then a matter of motor type? With the right motors rotational direction is just a matter of polarity. With the right motors PWM (Pulse Width Modulation) easily can control motor speed. This will always revert back to motor details which are unknown.

Ron
 

LowQCab

Joined Nov 6, 2012
4,078
Lots of "dead-space" in your video,
and no explanation of what "cleaning" means, ( does this mean "Bulk-Erasing" ? ).

Cleaning the Tape is not necessary, or advantageous,
cleaning the internal parts of the Play/Record-Machine with Alcohol
is "sometimes" advantageous after many hours of usage.
.
.
.
 

MisterBill2

Joined Jan 23, 2018
18,600
As the motors are described as DC motors, I am guessing permanent magnet brush type motors. As I did not watch the video I am guessing that the application is winding tape from one spool to another. with the intention of holding the speed close to constant, to achieve a reasonably uniform rewind. The serious hazard is allowing the pay-out spool to unwind faster than the take-up spool is winding up. THAT can cause some nasty tangles, as I have observed. So braking of the pay-out spool can be rather important.

As for "cleaning the tape, that may be needed on some occasions, as some tapes do get physically dirty. For serious bulk erasing, to remove every bit of data cleaning, a constant speed past a strong enough series of magnets can do the job. External bulk erasures are usually good enough for normal use, however.

The actual speed of a typical small DC motor in this sort of application can be done with a simple variable resistor. Not the most efficient scheme, but does this system get used enough to require better efficiency?? We really do not know.
 
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