Slowing DC motor

Status
Not open for further replies.
Y

Yeoman

Member
I received my new 2CH module today and have the 12v motor now operating forward/reverse as desired, remotely. This is a 6A module, motor is 3A.
What would be the simplest and most cost effective way to reduce the speed by half? Speed can be fixed, variable not necessary,
A diode on each motor leg? If so, how do I size the diode?
 

you will need to decrease the voltage. Either use a 6v or 9v supply (easiest) and many 12VDC controllers work just fine.

otherwise, you can add a PWM (pulse width modulated) controller to adjust the speed.
 
gophert said:
you will need to decrease the voltage. Either use a 6v or 9v supply (easiest) and many 12VDC controllers work just fine.

otherwise, you can add a PWM (pulse width modulated) controller to adjust the speed.
Click to expand...
I already have a 12v battery and 12v receiver to activate the motor. I know a PWM would be more flexible. Would a diode work? Maybe a Zener two-way since I’m reversing current?
 
Can you fit a 2:1 ratio belt and pulley on it?
Otherwise I would agree, a PWM control and a H-bridge driver for the Bi-direction.
Max.
 
Last edited:
Yeoman said:
I already have a 12v battery and 12v receiver to activate the motor. I know a PWM would be more flexible. Would a diode work? Maybe a Zener two-way since I’m reversing current?
Click to expand...

No, it would need to be HUGE zeners, probably mounted in heatsinks, and would give poor performance as well.

Perhaps you might try mentioning exactly what you're trying to do?, rather posting bits and bobs and keeping adding extra requirements.
 
If you PWMd a relay, would it just hover between contacts? Need to try that one day.

Mike.
 
Pommie said:
If you PWMd a relay, would it just hover between contacts? Need to try that one day.

Mike.
Click to expand...

Depends how fast you do it

Certainly relays have been used to create AC, as in vibrators used years ago to power valve equipment from low voltage batteries.
 
Not forgetting the car radio vibrator for producing the high voltage DC, the synchronous type switched both the primary and the secondary of the transformer to produce the rectification without the need for a rectifier tube ,
Max.
 
Last edited:
I am using a power window motor to turn a 1 inch diameter 6” pvc shaft onto which can be attached or inserted a variety of light weight objects for multiple purposes, with both forward and reverse direction, powered by a 12v, 7 amp hour battery, with all contents housed in a 10”x10”x5” portable box.
I am attempting to use, with exception of electrical switching/modulating components, items I have on hand. For instance, I have several 7ah 12v batteries I use for bilge pumps, a remote operated farm entrance cable, etc. and charge/swap them as needed.
I am satisfied with my current configuration of motor to shaft, housing, and forward/reverse remote operation, and would now simply like to slow the shaft rotation.
 

Attachments

  • image.jpg
    1.4 MB · Views: 141
Could you add a second, larger diameter pipe, and have the first drive that with a belt, or something?
That would give you a reduction in speed, but also an increase in torque.
 
As per #4 , It seems to me that gearing is still the best option, you have the maximum power of the motor, together with extra output torque due to gearing.
Max.
 
Unfortunately, a major limitation of these motors is that they are designed to turn a male tapered 1” to 1/2” nylon splined cone surrounding a 5/16 steel non-moving support shaft, onto which is inserted a female tapered splined 2” diameter nylon wheel. The combination is trapped by plastic housing in the automotive application, rendering the wheel inaccessible. Here, I’ve used the pvc slip fit over the nylon cone secured with screws to the appropriately 1/4” of available nylon. It wouldn’t be strong enough to tolerate lateral belt tension.
Here’s a version I built with a belt and turntable arrangement for 6:1 speed reduction driving off the 2” motor wheel but the whole thing is way larger than desired and not practical for several desired applications.
 

Attachments

  • image.jpg
    1.3 MB · Views: 148
MaxHeadRoom78 said:
Not forgetting the car radio vibrator for producing the high voltage DC, the synchronous type switched both the primary and the secondary of the transformer to produce the rectification without the need for a rectifier tube ,
Max.
Click to expand...

Which was what I was referring to.
 
Yeoman said:
Is a PWM not workable due to forward/reverse operation through remote activated receiver module?
Click to expand...

It's perfectly workable, just relatively complicated for you. Bear in mind as well that depending on load, the motor current could be considerable, the 3A 'rating' is going to be fairly nominal. You could use a single PWM in the 12V feed to the relays, so it works in either direction.
 
These motors have an internal circuit breaker. I know from testing, the motors shut down at 10lb dead weight lifting. I wouldn’t approach that in my applications if that helps.
I was concerned the PWM modulation would affect operation of the switching module? I guess not?
What makes the PWM complicated? Is it not just input from source, output to switching module?
 

If you've got a ready module, then yes.

It won't affect the switching 'module' because the only thing it's feeding is the relay contacts, and from there to the motor.
 
There are fairly heavy duty PWM modules on ebay for $3.00!
You would need to add the reverse direction feature though.
Max.
 
Status
Not open for further replies.

Similar threads

D
  • Question
Dc motor speed controller
Replies
5
Views
1K
aliarifat794
A
K
  • Question
How to determine wiring of DC motor controller
Replies
13
Views
1K
Diver300
D
L
  • Question
Consultation on DC motor voltage in linear actuator
Replies
3
Views
850
Tony Stewart
D
  • Question
Open Loop BLDC motor control, is it possible?
Replies
8
Views
2K
Tony Stewart
C
Components for AC-DC rectifier
Replies
13
Views
1K
danadak
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…