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• Medium Power 12v Brush Motor Speed Controller  New
  The circuit is a speed control for a medium power 12v DC operated single phase brush motor. It uses the brush current pulse method to monitor the motor speed.  It includes a method to limit the average motor current.  I have also included a means to turn on and off the motor from a simple TTL logic signal.   The circuit uses some rather old op amp ICs I had laying around. Other op amps and voltage comparators could also be used.  The circuit uses a pulse width modulation (PWM) scheme to control both the motor speed and the maximum average current.  The current control is handy when you want to limit the motor torque, since motor current and torque are directly related.  The circuit uses the current pulses from the motor brushes to extract the motor speed. For the motor I used, there were exactly 12 pulses per shaft rotation. The typical average motor current was about 1.2 amps with a speed of about 1000RPM.  At 1000 RPM, the pulse frequency works out to be 200Hz.

• Motor Brake
  This circuit will bring a fast moving DC motor to a stop in seconds.  The braking action is automatically applied whenever DC power is removed.  (added 12/04)

• PWM Circuit for Motor Speed Control
  Sometimes you want to slow down a brush type DC motor. The most efficient way to do this is with a pulse width modulation (PWM) technique. The hobby circuit below can operate from about 3 volts to 15 volts. The frequency is fixed at about 2KHz but the pulse width can be varied from nearly 100% to 0%. ...

Miniature high-rate speed control:  A miniature high-rate speed control published in the newsletter published by Electric Model Flyers' of Southwestern Ontario (diagram add

Miniature low-rate speed control:  A miniature low-rate speed control published in the newsletter published by Electric Model Flyers' of Southwestern Ontario (diagram added 11/06)

MOSFET  Switch provides efficient AC/DC conversion:  02/17/00 EDN-Design Ideas / (added 10/03)

MOSFET based speed controller uses 9 IRFZ40 power MOSFETS: 

MOSFET H-BRIDGE schematic and theory:  (diagram added 2/07)

Motor Control scheme yields four positions with two outputs:  02/07)/02  EDN Design Ideas / (added 10/03)    Figure 1 showshow to position a mechanical device into four discrete positions but with only two free outputs and one free input from the control system. The position depends on a set of cams and four corresponding limit switches. The 24V-dc motor comes with a worm gear. Darlington transistors Q3 to Q6 and resistors R7 to R12 form an H-bridge that drives the dc motor, M.

Motor Control Sensor Feedback Circuits:  Microchip Application Note Published 31-Dec-03   (app note added 2/06)

Motor Controller operates Without Tachometer Feedback:  12/09/99 EDN-Design Ideas / (added 2/06) /  This circuit uses a back-EMF for motor speed controlling to make a voltage controlled motor speed controller / Speed controllers have long exploited the reverse-EMF characteristics of dc motors to control their speed. These linear driver circuits use power op amps to create a negative resistance drive to the motor that counteracts the voltage drop in the motor's series resistance (Reference 1). The circuit in Figure 1 shows an implementation of this type of speed control using a PWM drive, which reduces power dissipation in the drive circuitry....

Motor Controller uses fleapower:  09/25/03 EDN Design Ideas  /  (added 1/05)  A simple, permanent-magnet dc motor is an essential element in a variety of products, such as toys, servo mechanisms, valve actuators, robots, and automotive electronics. In many of these applications, the motor must rotate in a given direction until the mechanism reaches the end of travel, at which point the motor must automatically stop....

Motor driver - 74*245-based :  A simple, time-honored approach is to use one or more 74*245 chips (normally  74AC245 is used for maximum current capability) to provide motor drive current. Here, each channel of drive power is provided by one or more buffer on  chip.   (added 1/07)

Motor speed Controllers:  (electronic circuit added 4/05)

Motor Speed Regulator:  This circuit regulates the speed of a small drill motor I use for PC board work. It is much handier for delicate work than a larger AC powered tool. The tool I have came with a useless 9 volt AC adapter. The motor would whine at high RPMs unloaded, but would slow to a crawl when loaded. This circuit solves the problem.   Designed by Andrew R. Morris  (added 09/05)

No-Hum Fan Controller:  (diagram added 2/07)

Noise Filtering and the ADT7461:  AN-699 Analog Devices Application Note   (app note added 2/06)

NuStepper:  Uses just a single IC ('though not one you're likely to have in your "parts box") to give you reversible motor drive   (added 11/05)

One component stepper motor Driver:  (electronic circuit added 4/05)

OptoCoupled Gate Detects Motor Operation:  02/02/98 EDN-Design Ideas / (added 3/03)  

Opto-coupled Servo Actuator:  (Schematic / Circuit added 1/07)

OptoElectronic position Control simplifies motor movements:  04/29/04 EDN Design Ideas  /  (added 1/05)  The optoelectronic technique for achieving position control provides an inexpensive, easy to-design method of achieving simple, repeatable movement using fixed index points with linear or rotary-motion components. The simple, basic design in Figure 1 for sequential position control exploits the quick response time of a power op amp, working in tandem with a pair of photodiodes....

PC-Based DC Motor Speed Controller:  (electronic circuit added 4/05)

PIC Based Motor Controller:  (circuit / schematic added 2/03)

Position detectors provide motor control logic:  05/24/01 EDN-Design Ideas / (added 2/06)

Power Chopper 1:  (Schematic added 11/06)

Programmable source powers dc micromotors:  03/01/01 EDN-Design Ideas / (added 2/06) A simple, economic, compact, and tricky way of using the LM723 as a programmable voltage source to drive dc micromotors which can set the output to a value of200 mV to 6V

Programming the Automatic Fan Speed Control Loop:  AN-613 Analog Devices Application Note   (app note added 2/06)

Pulse Width Modulation DC Motor Control:  controls the motor speed by driving the motor with short pulses (added 5/02)

Push Button Motor Control Circuits:  (diagram added 2/07)

PWM Controller Drives LEDs from high Voltage lines:  03/04/04 EDN Design Ideas  /  (added 1/05)  Powering LEDs from a wide dc range—say, 30 to 380V—without wasting a lot of power in the regulating block, is a difficult task when the LED current needs to be constant. Dedicated LED drivers are available, but they usually implement boost structures and are thus inadequate for high-voltage inputs....

PWM Controller:  555 Timer based PWM motor control project for electric fan or other DC motor (added 5/02)

PWM DC motor Control with SG3525:  (electronic circuit added 4/05)

PWM DC Motor Speed Control:  (electronic schematic / circuit added 4/02)

PWM motor Controller:  (electronic circuit added 4/05)

PWM Motor Speed Controller/DC Light Dimmer:  (electronic circuit added 4/05)

PWM Motor/Light Controller Variations:  diagrams are for12V operation and there are high side (common ground) and low side (common +12V) versions (added 5/02)

PWM Speed Control:  includes theory and some example circuits (added 5/02)