DC Motor Field Current Speed Control

Click For Summary
SUMMARY

The discussion centers on controlling the speed of a Geared DC Motor rated at 12V and 0.6A using a Field Current Control Circuit. The proposed circuit was deemed ineffective as it placed resistors in parallel with the motor, preventing speed modulation. Instead, a 555 Pulse Width Modulation (PWM) circuit is recommended for effective speed control, utilizing transistors to handle higher currents and ensuring the circuit is in series with the motor for proper functionality.

PREREQUISITES
  • Understanding of DC motor specifications (e.g., voltage, current, RPM)
  • Knowledge of circuit design principles, particularly series and parallel configurations
  • Familiarity with 555 Timer IC and its applications in PWM circuits
  • Basic electronics skills, including resistor and potentiometer ratings
NEXT STEPS
  • Research 555 Timer PWM circuit design for DC motor speed control
  • Learn about transistor switching for high current applications
  • Explore theoretical resistance calculations for motor control circuits
  • Investigate the implications of load and impedance on motor performance
USEFUL FOR

Electronics enthusiasts, hobbyists building motor control systems, and engineers designing variable speed applications for DC motors.

OvaR8ed
Messages
2
Reaction score
0
I have a Geared DC Motor rated 12V, 0.6A, 180RPM, 3kg.cm, 66% Efficiency. I measured the impedance of the disconnected motor at 45 Ohm.

I want to use it with a with a simple 12V 1A DC Power Supply in a Field Current Control Circuit to be able to dial in variable speeds.

Will the circuit in the attached diagram work?

What are good Theoretical Resistance values to start with for R1 and the Potentiometer to give me a wide range of speeds with no load on the motor?

For which Wattage should the Resistor and POT be rated to deal with the currents correctly?

Thanks in advance!
 

Attachments

  • IMG_1093.jpg
    IMG_1093.jpg
    24.4 KB · Views: 604
Engineering news on Phys.org
That circuit won't do anything. The resistors are simply another load on the 12 volt supply.
 
Yeah, I realized that. It could work if you limit your current at the power source, but that will over complicate things.

I'm rather going with a simple 555 Pulse Width Modulation circuit...
 
first of all yes for high amps a pot will be a waste of energy you have to use switches like transistors, the other thing the device needs to be in series with the motor , you circuit as you probably realized by now is in parallel with the motor so the motor would still go full speed.
 

Thread 'uA709 op amp compensation'

Most likely this can only be answered by an "old timer". I am making measurements on an uA709 op amp (metal can). I would like to calculate the frequency rolloff curves (I can measure them). I assume the compensation is via the miller effect. To do the calculations I would need to know the gain of the transistors and the effective resistance seen at the compensation terminals, not including the values I put there. Anyone know those values?
View full post »

Similar threads

12V DC Motor in Light Fixture with Dimmer & 12V DC to 110V AC Inverter
  • · Replies 21 ·
Replies
21
Views
2K
Controlling motor speed digitally
  • · Replies 11 ·
Replies
11
Views
2K
What is the best DC motor for spinning a vortex impeller at 3000 rpm?
  • · Replies 2 ·
Replies
2
Views
2K
High Current 12V DC motor speed control
  • · Replies 6 ·
Replies
6
Views
3K
Wheelchair motor, "Skid Steer" style control
  • · Replies 1 ·
Replies
1
Views
3K
Need help with my project -- microcontroller for DC motor controller
  • · Replies 3 ·
Replies
3
Views
2K
Measuring motor resistance and speed of a geared DC motor
  • · Replies 8 ·
Replies
8
Views
3K
DC motors -- speed control question
  • · Replies 6 ·
Replies
6
Views
3K
BLDC motor as generator to power eddy current brakes
  • · Replies 7 ·
Replies
7
Views
3K
DC Motor Controls: Get Help for Layman's Terms
  • · Replies 14 ·
Replies
14
Views
4K