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Pulse Width Modulators (PWM), page 3
PWM Circuits:  #-A     B-O     P     Q-Z

Last Updated on: Friday, October 03, 2014 10:38 AM

Circuits Designed by Dave Johnson, P.E. :

  • 555 Timer Forms Simple PWM Motor Controller
    Using a CMOS version of the 555 timer, this circuit can be used to control the speed of a motor by adjusting the duty cycle of the pulses sent to the motor. (added 7/06)
  • 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%. ...
  • Reduced Power Relay Driver  Aug 3, 2008
    Relays can handle a lot of power.  However, for certain power sensitive designs you would like to reduce the power needed to hold a relay closed.  The circuit below performs such a task.  It uses a single CD4093 quad NAND gate.  When the “on” logic input signal is detected, the relay is first pulsed on for about 500ms.  This is sufficient time to insure the relay is fully closed.  After that initial pulse the relay is then driven with a square wave signal, whose duty cycle can be adjusted.  The signal duty cycle can be adjusted from about 10% to 90%.  In most cases a 50% duty cycle will hold the relay closed.  This reduces the average DC current required by the same factor, which means a 4:1 reduction in power. The circuit can operate over a wide 3v to 15v range.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:
PLD code creates PWM generators -  8-Aug-02 Issue of EDN  The PLD (programmable-logic-device] code in Listing 1 creates arbitrary-resolution, pulse-width-modulated (PWM] generators. PWM generators are useful as low-bandwidth D/A converters in hardware of microprocessor-based.... [Design Idea by Clive Bolton, Bolton Engineering Inc, Melrose, MA]
PPM & VU Meter -  A versatile and useful VU meter circuit, can also operate as a Peak Program Meter   (circuit added 6/07)
Processor's PWM output controls LCD/LED driver -  27-May-04 Issue of EDN  The PWM (pulse-width-modulation] output available from many microprocessors is based on an internal 8- or 16-bit counter and features a programmable duty cycle.... [Design Idea by Joe Neubauer, Maxim Integrated Products, Sunnyvale, CA]
Provide 4- to 20-mA PWM control -  09/01/98 EDN-Design Ideas....The circuits in Figure 1  and Figure 3 are useful when you use 4- to 20-mA current-loop signals to control a PWM signal. In both circuits,...File has many circuits, scroll down.... [Design Idea by Tom Gay, Darmstadt, Germany]

Pulse Width Modulation -  ....(spice design added 02/09)
Pulse Width Modulation DC Motor Control (Aaron Cake) -  controls the motor speed by driving the motor with short pulses (added 5/02)
Pulse Width Modulator, CD4093  -  The IC used is a CMOS type MC14093, a quad 2-input NAND Schmitt trigger. If you wish, it can be directly interchanged with the CMOS MC14011 but this type is noisy.The speed is adjustable from 0-max. Max rpm is 2/3 the supply voltage.…. [Tony van Roon's circuit]
Pulse Width Modulator, LM324 -  Schematic only, no circuit description included…. [Design adapted by Tony van Roon's circuit]
Pulse Width Modulator, NE555 -  This circuit is capable of regulating 12V motors and DC light bulbs. No coolrib required for Q1 or D3 if the current does not exceed 2A. If it does, a sufficient coolrib for both the Schottky Diode (D3) and MosFET Q1 is required.…. [Tony van Roon's circuit]
Pulse Width Modulators -  generating PWM waveform is extremely simple with the circuits shown in this page (added 5/02)
Pulse Width-to-Voltage Converter -  (electronic schematic / circuit added 4/02)
Pulse-width modulator has digital control -  12-Jun-08 Issue of EDN  Operating at 1 Hz, this pulse-width modulator has digital control.... [Design Idea by S Vinay Kumar, Mysore, India]
PWM AC/DC Power Supply Design Apex-AN35 -  Apex App Note....
PWM ADC is Surprisingly Accurate -  06/09/94 EDN-Design Ideas....The reference voltage in Fig 1a's simple rail-to-rail PWM ADC is the only critical component. The input-voltage range extends from ground to the power rail which also acts as the reference. The circuit is essentially a variation on the classic dual-slope integrator,.... EDN is migrating links. This link is not verified.  Google the "title" + EDN for new link.
PWM Basics Apex-AN30 -  Apex App Note....
PWM circuit controls sensor's AGC -  03/29/01 EDN-Design Ideas...All electronic sensors have their limits on working distances and environmental tolerances. Dynamic range defines a sensor's maximum allowable variations in the signal amplitude. ACG (automatic gain control) finds widespread use in systems to extend the dynamic range. Applications using photoelectric or ultrasonic techniques involve both emission and detection energy. In many cases, the emission first establishes a background receiver signal as a reference, and the receiver monitors the signal and detects any changes against this reference....[Dongjie Cheng, Allegro Microsystems, Willow Grove, PA]
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%.... [Hobby Corner Circuit by Dave Johnson]
PWM circuit uses fuse to sense Current -  12/23/99 EDN-Design Ideas.... EDN is migrating links. This link is not verified.  Search the "title" + EDN for new link.
PWM Circuit uses One OpAmp -  07/06/00 EDN-Design Ideas....circuit delivers a rectangular signal with duty cycle varying between0 and100% in response to an input signal varying from0 to5V dc.... EDN is migrating links. This link is not verified.  Google the "title" + EDN for new link.
PWM Circuit with 4 transistors -  I have not built it, but it looks like it should work. It might be a good idea to put a resistor between the control pot's wiper and +VCC to limit the transistor base current. [G. Forrest Cook]
PWM Control for  Hydrogen Generators -  Unlike conventional PWM Circuits,This circuit also has a special "Current Limit Control". "If your H-Cell gets hotter and tries to draw more current,This circuit won't let it"…..(circuit / schematic design added 11/06)
PWM Controller -  This controller will deliver up to 30 amps and control the motor from 5% to 95%.
PWM Controller -  555 Timer based PWM motor control project for electric fan or other DC motor (added 4/02)

PWM controller drives LEDs from High-Voltage lines -  4-Mar-04 Issue of EDN  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.... [Design Idea by Christophe Basso, On Semiconductor, Toulouse, France]
PWM DC Motor Control with SG3525 -  This control circuit is ideal for the accurate control of DC motors as well as other applications like lighting levels and small heaters etc. The circuit converts a DC voltage into series of pulses, such that the pulse duration is directly proportion to the value of the DC voltage. The great advantage of such a circuit is that almost no power is lost in the control circuit....(electronic circuit added 4/05)
PWM DC Motor Speed Control -  This is a circuit for controlling the speed of small DC motors, it works nicely as a speed controller for an HO or N gauge model railroad… [Circuit Design by G. Forrest Cook]
PWM fan Controller -  I noticed allot of people like to use the 7V fan mod, this is fine I suppose but it is very inefficient, and it doesn't allow for RPM monitoring. I have Built a fan controller out of fairly cheap and readily available parts that is extremely efficient, reliable and doesn't endanger your computers PSU.….(electronic schematic added 06/09)
PWM Functionality Test Apex-AN34 -  Apex App Note....
PWM Low Pass Filtering Apex-AN32 -  Apex App Note....
PWM Methods for Expanding CCRL Dimming Range Using the ML4877 or ML4878/ ABR-42023 -  Fairchild Application Notes / (app note added 6/06)
PWM Motor Controller -  Schematic only, no circuit description [drawn by Rich Rudman]
PWM Motor Speed Controller/DC Light Dimmer -  DC Light Dimmer using a LM324 IC…. [G. Forrest Cook]
PWM Motor/Light Controller -  The diagrams are for 12V operation only and there are high side (common ground) and low side (common +12V) versions. The low side version of the circuit uses an N Channel FET, the high side version of the circuit uses a P Channel FET. N Channel devices tend to handle more current than P Channel devices, they are also less expensive. The high side version of the circuit is useful when one side of the load has to be grounded.... [G. Forrest Cook]
PWM Power Amplifier -  Based on the ColdAmp BP4078 400W module, Class-D is here. Definitely worth looking at!  ....
PWM Speed Control -  includes theory and some example circuits (added 4/02)
PWM Subwoofer Amplifier -  Using a ColdAmp BP4078 module, this article has complete construction details  ....
PWM using 555 -  A simple oscilator with PWM that can be used to control speed of motors or light intensity. (4/29/2006)
PWM Watchdog Circuit Ensures upper Bounds -  11/07/96 EDN-Design Ideas   With PWM control of power factor, you need a continuous check on excess pulse width and dead periods to protect a variety of systems that may not incorporate such protection. You also need regular pulsed power to ensure good averaged, reconstructed.... [Design Idea by Shyam Tiwari, IGCAR, Kalpakkam, India]
PWM White LED Drivers -  (electronic circuit added 4/05)
PWM with 555 -  Some useful circuits using the LM555 IC.Scroll to find the PWM with 555 circuit (11/06)
PWM, a Software Solution using the 16CXXX Devices -  Microchip Application Note Published 26-Aug-97  (app note added 06/06/06)
PWMA High Current Pulse Width ControlExcellent & Real Simple! -  Newly Revise Design NOW for Either N or P Channel Mos-Fet's....(design added 12/08)

PWM Circuits:  #-A     B-O     P     Q-Z

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