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Pulse Width Modulators (PWM)
PWM Circuits:  # - G     H - O     P - S     T - Z

 

Last Updated: October 18, 2017 05:04 AM

Circuits Designed by Dave Johnson, P.E. :

 

555 Timer Forms Simple Circuit 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. . . Circuit by Dave Johnson P.E.-February, 2007

Classic Linear 5v Supply using 6.3VAC Transformer - There are times when you wish to control a pulse width modulation (PWM) signal with a DC voltage, ranging from 0v to 5v.  This voltage is often created by a computer interface.  The circuit below performs this voltage to PWM conversion.  PWM signals are often . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2010

Computer Controlled PWM Circuit - There are times when you wish to control a pulse width modulation (PWM) signal with a DC voltage, ranging from 0v to 5v.  This voltage is often created by a computer interface.  The circuit below performs this voltage to PWM conversion.  PWM signals are often. . . Circuit by Dave Johnson P.E.-October, 2010

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 . . . Hobby Circuit designed by David Johnson P.E.-December, 2007

PWM Motor Controller uses a 555 Timer - 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 . . . Hobby Circuit designed by David Johnson P.E.-February, 2007

Reduced Power Relay Driver - 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. . . Circuit by David Johnson P.E.-August, 2008

Relay Driver with Reduced Power - 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 . . . Hobby Circuit designed by David A. Johnson P.E.-August, 2008

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P/pwm.htm       Page 1

12V 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 __ Designed by G. Forrest Cook

1-Shot Remembers Input-Pulse Width-  07/18/96  EDN Design Ideas:  The circuit in Figure 1a remembers the width of an input pulse at the in terminal.  After the input pulse returns to zero, a trigger input causes an output pulse to occur at the out terminal.  This output pulse is proportional to the width of the input pulse.  R2 and R3 set this pulse-width ratio.  For the values shown, the output pulse is half __ Circuit Design by Ray Kauffman, Electronic Devices Inc, Chesapeake, VA

2-channel Audio Amplifier drives stepper Motor-  12/01/06  EDN Design Ideas:  Pulse-width-modulated stereo power amplifier saves components __ Circuit Design by Phill Leyva and Bill Quach, Maxim Integrated Products, Sunnyvale, CA

555 Pulse Width Modulator-  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 __ Designed by Tony van Roon  VA3AVR

555 timer converted into pulse-width Modulator-  15-Feb-07 EDN Design Ideas:  Added CMOS switch enhances a PWM oscillator __ Circuit Design by Jordan Dimitrov, Tradeport Electronics, Vaughan, ON, Canada

555 Timer Forms Simple Circuit 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. . . Circuit by Dave Johnson P.E.-February, 2007

7 by 10 LED Moving Sign-  This sign uses two LED arrays to form a 7 X 10 matrix.  It produces moving messages or animations stored in an EPROM.  It uses no microprocessor. As in most electric signs, the LEDs are matrixed, and strobed very quickly. __ Designed by Bob Blick

8 Channel PWM Code AVR Controllers-  This article is about a software controlled, parallel port-interfacing 8-channel Pulse-Width-Modulated fan controller __ Designed by Dick Cappels

Accurate, fast settling analog voltages from PWM signals-  EDN Design Ideas:  05/31/2016  LTC Design Notes:  A unique IC mitigates the disadvantages of PWM DACs __ Circuit Design by LTC Design Note

Active-clamp/reset-PWM IC becomes More versatile-  26-Jun-03 EDN Design Ideas:  The UCC3580 (www. Ti.com], IC1 in Figure 1, is an active-clamp/reset-PWM IC that has all the requisites of a power-supply IC except for current limit.  You can use the shutdown pin (16] for this purpose (see the UCC3580 data sheet].  But when the shutdown pin activates, the soft-start capacitor normally connected to Pin 15 discharges, and the converter starts again, resulting in hiccup mode __ Circuit Design by Gowripathi and M Sindhu, ITI Ltd, Bangalore, India

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 __ Circuit Design by Mike Walne, Farnell Instruments, Wetherby , West Yorkshire, UK

Analog switch converts 555 timer into pulse-width Modulator-  15-Feb-07 EDN Design Ideas:  Added CMOS switch enhances a PWM oscillator __ Circuit Design by Jordan Dimitrov, Tradeport Electronics, Vaughan, ON, Canada

Buffer Amplifier & LED improve PWM power controller's low-load operation-  09/15/05 EDN Design Ideas:  PWM IC is enhanced with discrete components for wider-range operation __ Designed by Gregory Mirsky, LaMarche Manufacturing Co, Des Plaines, IL

Build a Simple Circuit Complementary-Bracket-Pulse Generator-  20-Aug-09 EDN Design Ideas:  When building push-pull switching power converters or motor controllers, you often need alternating pulses with a small amount of dead time between them to minimize simultaneous conduction in output-switching devices.  Switching controller ICs have this feature, but they usually operate __ Circuit Design by Horst Koelzow, Global Thermoelectric, Calgary, AB, Canada

CD4093 Pulse Width Modulator-  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 __ Designed by Tony van Roon  VA3AVR

Cheap PWM IC makes synchronous gate driver-  02/04/99 EDN Design Ideas:    NOTE:    Page includes several designs.  Scroll to find this one.  A system with a µP, memory, and peripherals usually requires several power-supply voltages.  Designers typically use local switching regulators to produce the desired voltage rails.  One of the most common topologies, the synchronous buck regulator, converts a 5 or 12V bus to some other, lower voltage.  This approach has gained vast acceptance, thanks to its relative simplicity __ Circuit Design by Dimitry Goder, Switch Power Inc, Campbell, CA

Circuit Allows Long PWM Soft Starts-  02/01/07  EDN Design Ideas:  Enhance timing accuracy of a switching regulator's start-up ramp __ Circuit Design by Robert N Buono, Aeolian Audio LLC, Bloomfield, NJ

Circuit converts pulse width to voltage-  10/25/01 EDN Design Ideas:  The circuit in Figure 1 converts pulse information to a clean dc voltage by the end of a single incoming pulse.  In another technique, an RC filter can convert a PWM signal to an averaged dc voltage, but this method is slow in responding.  Converting low-duty-cycle pulse information is slower yet __ Circuit Design by James Mahoney, Linear Technology Corp, Milpitas, CA

Circuit maximizes pulse-width-modulated DAC throughput-  03/22/13  EDN Design Ideas:  This ramp-based DAC uses microcontroller-generated clocks and a sample-and-hold.  Simple DACs realized by lowpass filtering microcontroller-generated pulse-width-modulated (PWM) signals have a response that is typically a tenth of the PWM frequency.  This Design Idea is a novel implementation of a previously published method1 employing a reference ramp whose output is sampled and held by the PWM signal.  This approach results in a throughput rate equal to the PWM frequency. __ Circuit Design by Ajoy Raman

Circuit provides 4- to 20-mA loop for microcontrollers-  05/27/04  EDN Design Ideas:  The 4- to 20-mA current loop is ubiquitous in the world of controls in manufacturing plants.  Discrete logic, microprocessors, and microcontrollers easily cover the digital portions of control schemes, such as limit switches, pushbuttons, and signal lights.  Interfacing a 4- to 20-mA output to a rudimentary microcontroller can be problematic __ Circuit Design by Robert Most, Dow Corning Corp, Auburn, MI

Circuit Provides Efficient PWM-  02/18/99 EDN Design Ideas:    NOTE:     Page includes several designs.  Scroll to find this one.  You often need to control the duty cycle of a square wave.  The circuit in Figure 1 works from a single 5V supply at a frequency of 100 kHz.  With minor component changes, you can configure it for a range of frequencies.  The circuit consists of a ramp   NOTE:  sawtooth]oscillator __ Circuit Design by Kenneth Levine, Eldec, Lynwood, WA

Circuit Sequences Supplies for FPGAs-  01/23/03 EDN Design Ideas:  System designers must consider the timing and voltage differences between core and I/O power supplies (in other words, power-supply sequencing] during power-up and power-down.  The possibility of a latch-up failure or excessive current draw exists when power-supply sequencing does not occur properly.  The trigger for latch-up may occur if power supplies apply different potentials to the core and __ Circuit Design by David Daniels, Texas Instruments, Dallas, TX

Circuits 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, the minimum pulse width (corresponding to a 4-mA loop current) and the maximum pulse width (corresponding to a 20-mA loop current) are independently   FILE has many circuits, scroll down __ Circuit Design by Tom Gay, Darmstadt, Germany

Classic Linear 5v Supply using 6.3VAC Transformer-  There are times when you wish to control a pulse width modulation ( PWM) signal with a DC voltage, ranging from 0v to 5v.  This voltage is often created by a computer interface.  The circuit below performs this voltage to PWM conversion.  PWM signals are often . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2010

Computer Controlled PWM Circuit-  There are times when you wish to control a pulse width modulation ( PWM) signal with a DC voltage, ranging from 0v to 5v.  This voltage is often created by a computer interface.  The circuit below performs this voltage to PWM conversion.  PWM signals are often. . . Circuit by Dave Johnson P.E.-October, 2010

Control an LM317T with a PWM Signal-  02/03/11  EDN Design Ideas:  Set a regulator's output voltage under microprocessor control.  The LM317T from National Semiconductor is a popular adjustable-voltage regulator that provide as output voltages of 1.25 to 37V with maximum 1.5A current.  You can adjust the output voltage with a potentiometer.  The circuit in Figure 1 replaces the potentiometer with an analog voltage that you can control from a PWM (pulse-width-modulation) signal.  You control this signal with a microcontroller or any other digital circuit.  You can use the same microcontroller to dynamically monitor the output and adjust the LM317T. __ Circuit Design by Aruna Rubasinghe

Convert Pulse Width to Voltage-  10/25/01 EDN Design Ideas:  The circuit in Figure 1 converts pulse information to a clean dc voltage by the end of a single incoming pulse.  In another technique, an RC filter can convert a PWM signal to an averaged dc voltage, but this method is slow in responding.  Converting low-duty-cycle pulse information is slower yet __ Circuit Design by James Mahoney, Linear Technology Corp, Milpitas, CA

Convert Pulse Width to Voltage-  10/28/99 EDN Design Ideas:  The circuit in Figure 1 stems from a radio-controlled modeling application, which requires a voltage proportional to the width of the incoming servo pulses.  The circuit is optimized for a positive-going pulse width of 1 to 2 msec, repeating at intervals of approximately 17 msec.  The output produces a voltage of 0.95V for a 1-msec pulse to 2.25V for a 2-msec pulse. __ Circuit Design by Ron Hegler, Picker International, Cleveland, OH

Current mirror improves PWM regulator’s performance-  1-Mar-07 EDN Design Ideas:  Reduce Miller Effect to enhance an SMPS' performance and reduce component count __ Circuit Design by Grant Smith, National Semiconductor, Phoenix, AZ

DDS Generates Precise PWM Waveforms-  10/02/03  EDN Design Ideas:  Pulse-width modulation is a simple way to modulate, or change, a square wave.  In its basic form, the duty cycle of the square wave changes according to some input.  The duty cycle is the ratio of high and low times in the square wave __ Circuit Design by Colm Slattery Analog Devices, Limerick, Ireland

Dual Ramp Generator-  Several schematics on this page, scroll to find this one.  The first circuit is a dual ramp generator where the positive and negative ramps are generated separately.  This circuit was used as a ramp generator for a transistor curve tracer: the positive going ramp was used for testing NPN transistors and the negative ramp for testing PNP transistors. __ Designed by Richard Torrens

Fast-Settling Synchronous-PWM-DAC Filter Has Almost No Ripple-  05/01/08  EDN Design Ideas:  An inexpensive, high-resoultion DAC uses a synchronous output filter that settles in one PWM cycle __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

FET biasing targets battery-powered PWM applications-  11/21/05 EDN Design Ideas:  Reference provide as constant bias voltage regardless of supply-voltage variations __ Circuit Design by Steve Franks, Franks Development LLC, Tucson, AZ

Form Positive Pulses From Negative Pulses-  07/14/11  EDN Design Ideas:  Create positive pulses even when negative pulses vary in amplitude.  The circuit in this Design Idea converts negative pulses to positive pulses.  Although that task may seem simple, the negative pulses have amplitudes of −5 to −2V.  The positive pulses also need different pulse widths, depending on the application, and the negative pulses are trapezoidal.  The pulses must travel over a long-distance transmission line to a control device.  Several circuits solve the problem, depending on the amplitude and shape of the pulses. __ Circuit Design by Vladimir Rentyuk, Zaporozhye, Ukraine

Fuel Injector Pulse Width Monitor-  Shown below is the schematic for the pulse width monitor.  The heart of the circuit is the transistor current source which charges cap C10 to form an integrator.  The theory is that the cap is charged and the voltage across it increases linearly for the amount of time that the injector is energized.  As the injector is switched off the voltage in C10 is stored in cap C9 and then C10 is reset to 0 volts to get ready for the next cycle.  The output of the circuit is the voltage across cap C9, this voltage is fed directly into U3 the bar graph chip to be displayed as a value betw1een 1-10 on the LEDs. __

Generate a Pulse Width that Is Inversely Proportional to the Square Root Of an Analog Voltage-  EDN-Design Ideas -- 05/24/12  This non-retriggerable monostable circuit performs analog conversion of a mathemetical function to time. __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Generate stabilized PWM signals-  08/17/00 EDN Design Ideas: A standard technique for generating analog voltages using µCs is to use a PWM output and filter the signal with a simple RC filter ( Figure 1).  The voltage of the PWM signal is directly proportional to theµC's supply voltage, so __ Circuit Design by Martin Ossmann, FH, Aachen, Germany

Generator has independent pulse width, frequency-  11/11/99 - EDN Design Ideas:  A common circuit in electronics is the square-wave, astable multivibrator (one-shot) , which is useful for various purposes, such as timing circuits and audible alarms.  The most common way to generate the desired square wave is to use the inexpensive 555 timer.  The need sometimes arises for a square wave with fixed frequency but variable pulse width or vice versa. __ Circuit Design by Davinder Oberoi

 

P/pwm.htm       PAGE 3

PLD code reveals PC-Board revisions-  10/17/02 EDN Design Ideas:  The PLD (programmable-logic-device] code in Listing 1 implements a pc-board-level revision-detection system that detects whether PLD pins are shorted together on a pc board.  It is often advantageous to field a single PLD programming file that works for several generations of physical hardware.  The PLD needs to understand what the board revision is, so that it can enable or disable functions, pi __ Circuit Design by Clive Bolton, Bolton Engineering Inc, Melrose, MA

Power MOSFET PWM motor driver-  Scroll down: 
This power MOSFET motor driver is better than the PROFET driver because it is working at a higher switch frequency of 20 kHz. This circuit also avoids the voltage drop and power loss over the power diodes present in the PROFET driver. The MOSFET transistor in this motor driver requires a special driver circuit between the PWM circuit and the MOSFET itself. The reason for this is that switching the gate voltage of the MOSFET transistor requires high transient current ( 2 A) due to relatively high capacitive load. The MOSFET transistor requires a relatively large heatsink for high current motors. __ Contact Pico Technology

Processor's PWM output controls LCD/LED driver-  27-May-04 EDN Design Ideas:  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.  It is suitable for adjusting the output of an LCD driver (Figure 1) , a negative-voltage LCD driver (Figure 2], or a current-controlled LED driver (Figure 3] __ Circuit Design 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, the minimum pulse width (corresponding to a 4-mA loop current) and the maximum pulse width (corresponding to a 20-mA loop current) are independently   FILE has many circuits, scroll down __ Circuit Design by Tom Gay, Darmstadt, Germany

Provides Efficient PWM-  02/18/99 EDN Design Ideas:    NOTE:     FILE has several circuits, scroll to find this one You often need to control the duty cycle of a square wave.  The circuit in Figure 1 works from a single 5V supply at a frequency of 100 kHz.  With minor component changes, you can configure it for a range of frequencies.  The circuit consists of a ramp   NOTE:  sawtooth.  oscillator and a comparator.  The circuit compares the ramp to an externally applied voltage, VCNTRL.  When VCNTRL is greater than the ramp voltage, the PWM output is 5V.  The sawtooth oscillator consists of a current source   NOTE:  R1, R2, R3, and Q1.  , a timing capacitor   NOTE:  C1.  , and the oscillator-control circuitry   NOTE:  R4, R5, R6, and IC1A The oscillator-control circuitry sets the upper and lower voltages of the timing capacitor at 3 and 1V. __ Circuit Design by Kenneth Levine, Eldec, Lynwood, WA

Pulse width Modudulator using 555 timer IC-  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 __ Designed by Tony van Roon  VA3AVR

Pulse Width Modulation-  (spice design) __ Designed by Rick 

Pulse Width Modulation DC Motor Control-  Often, people attempt to control DC motors with a variable resistor or variable resistor connected to a transistor.  While the latter approach works well, it generates heat and hence wastes power.  This simple pulse width modulation DC motor control eliminates these problems.  It controls the motor speed by driving the motor with short pulses.  These pulses vary in duration to change the speed of the motor.  The longer the pulses, the faster the motor turns, and vice versa. __ Designed by Aaron Cake

Pulse Width Modulator-  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 __ Designed by Tony van Roon  VA3AVR

Pulse Width Modulator, LM324-  Schematic only, no circuits description. __ Designed by Tony van Roon  VA3AVR

Pulse Width Modulators-  generating PWM waveform is extremely simple with the circuits shown in this page __ Designed by Richard Torrens

Pulse Width Position Servo control-  I have described elsewhere in these pages how normal PWM works in controlling the speed of a motor.  PWPS is an entirely different system and two should not be confused: the similarity of names is unfortunate and I suggest you forget everything you know about ordinary PWM motor speed control so you can follow this explanation. __ Designed by Richard Torrens

Pulse Width-to-Voltage Converter-  This is the circuitry that we evolved ( and discarded!) for the interface.  It is in two parts because of the mechanical design of the caddy.  The first half is a speed interface which simply translates the standard radio control pulse width to an analogue voltage which is fed to one of 4QDs motor speed controllers.  I know - the circuit looks too complicated for such a simple task, but it is in fact doing a few other tasks that the customer required. __ Designed by Richard Torrens

Pulse-Width Modulator Has Digital Control-  12-Jun-08 EDN Design Ideas:  Operating at 1 Hz, this pulse-width modulator has digital control __ Circuit Design by S Vinay Kumar, Mysore, India

PUT pair-  2 Tr equivalent to SCRs, SCSs and other 4 layer devices __ Designed by Richard Torrens

PWM a High Current Pulse Width Control-  Newly Revise Design NOW for Either N or P Channel Mos-Fet's __ Designed by G.L. Chemelec

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 __ Circuit Design by Mike Walne, Farnell Instruments, Wetherby, West Yorkshire, UK

PWM CD4094-  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 __ Designed by Tony van Roon  VA3AVR

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 . . . Hobby Circuit designed by David Johnson P.E.-December, 2007

PWM Control forHydrogen 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". __ Designed by G.L. Chemelec

PWM Controller-  This controller will deliver up to 30 amps and control the motor from 5% to 95%. __ 555-Timer

PWM Controller-  This PWM controller is cheap and easy to build, but has no temperature control and with components shown runs at relatively low frequency. __ Designed by © Madis Kaal

PWM controller drives LEDs from high-voltage lines-  4-Mar-04 EDN Design Ideas:  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 __ Circuit Design by Christophe Basso, On Semiconductor, Toulouse, France

PWM 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 wIdeaspread 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 __ Circuit Design by Dongjie Cheng, Allegro Microsystems, Willow Grove, PA/

PWM DC Motor control with SG3525-  This PWM DC Motor driver 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 __ Contact info @ wzmicro.com

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 __ Designed by G. Forrest Cook

PWM DC Power Controller-  This DC power supply controller is controlled by pulse width modulation PWM, generated by the circuit around timer IC2 7555 according to the formula: Duty cycle = ( ( R1 + ( VR1/2) / ( R1+R2+VR1)) x 100% Diode D1 is used to bypass resistor R2 and half the effective resistance of the “lower” section of VR1, allowing the __ Designed by Popescu Marian

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__

PWM fan controller in an EMI-susceptible-  02/16/06  EDN Design Ideas:  Control it with either an external negative-temperature-coefficient thermistor or a PIC microcontroller and its SMBus serial-data bus __ Circuit Design by Dimitri Danyuk, Niles Audio Corp

PWM has digital control-  12-Jun-08 EDN Design Ideas:  Operating at 1 Hz, this pulse-width modulator has digital control __ Circuit Design by S Vinay Kumar, Mysore, India

PWM IC makes synchronous gate driver-  02/02/99 EDN-Design Ideas (contains several designs, scroll to find this one) A system with a µP, memory, and peripherals usually requires several power-supply voltages.  Designers typically use local switching regulators to produce the desired voltage rails.  One of the most common topologies, the synchronous buck regulator, converts a 5 or 12V bus to some other, lower voltage. __ Circuit Design by Dimitry Goder, Switch Power Inc, Campbell, CA

PWM Logic Based Low Power MW AM Transmitter-  You can use this for safely linking your iPod to that super-retro AM valve radio that you just bought. __ Designed by Henry 

Pwm Modulator-  If you ever thought of experimenting with pulse-width modulation, this circuit should get you started nicely.  We’ve kept simplicity in mind and used a dual 555 timer, making the circuit a piece of cake.  We have even designed a small PCB for this, so building it shouldn’t be a problem at all.  This certainly isn’t__

PWM Motor Control-  PIC Project  This device acts as a variable speed control for the heater blower in a car.  It takes its power directly from the existing wiring and connects with just 2 wires.  It will also work for any 12 volt device up to 10 amps. __ Designed by Luhan Monat - Mesa Arizona

PWM Motor Controller-  Schematic only, no circuit description__ drawn Rich Rudman

PWM Motor Controller uses a 555 Timer-  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 . . . Hobby Circuit designed by David Johnson P.E.-February, 2007

P/pwm.htm       PAGE 5

Tank Heater-  a PWM power controller used to control the temperature in a tank for a tarantula __ Contact P. Townshend - EduTek Ltd

The +12 V power supply-  Scroll down:  The small current parts ( not the motor itself) could be powered from a +12 V voltage regulator. Then the input voltage must be larger than +15  V. The regulator survives a current of maximum 1 A with a heatsink. __ Contact Pico Technology

Timer with 555-  Some useful circuits using the LM555 IC.  Scroll to find the Timer with 555 circuit __ Designed by Jose Pino

Transistor paIR lowers PWM IC's start-up current -  03/18/99 EDN Design Ideas:  An auxiliary winding usually provide as power for the popular  UC384X-based offline switch-mode power supplies (SMPSs).  This winding feeds  the main PWM controller. PDF contains multiple circuits, scroll to find this circuit. __ Circuit Design by Christophe Basso, Motorola Semiconductor, Toulouse, France

Two-channel audio Amplifier drives stepper Motor-  12/01/06  EDN Design Ideas:  Pulse-width-modulated stereo power amplifier saves components __ Circuit Design by Phill Leyva and Bill Quach, Maxim Integrated Products, Sunnyvale, CA

Unused Port Adds a PWM/Analog Channel to a Microcontroller-  8-Oct-09 EDN Design Ideas:  Take advantage of unused pins to generate a PWM signal and then filter it into analog __ Circuit Design by Vishwas Vaidya, Tata Motors Ltd, Pune, India

Use a Low-Cost PWM Ramp Generator In Switch-Mode Power Supplies-  04/08/10 EDN Design Ideas:  Include this circuit in a switching-power-supply design. __ Circuit Design by Dwayne Reid, Edmonton, AB, Canada

Use a PWM fan controller in an EMI-susceptible-  02/16/06  EDN Design Ideas:  Control it with either an external negative-temperature-coefficient thermistor or a PIC microcontroller and its SMBus serial-data bus __ Circuit Design by Dimitri Danyuk, Niles Audio Corp

Using a Function Generator to Create Pulse Width Modulation PWM Waveforms-  Application Note__ Aligent

Variable Frequency PWM-  Schematic only, no circuits description. __ Designed by Tony van Roon  VA3AVR

Video Design Idea: Leverage PWM output & add a low-cost DAC to your system-  07/19/07 EDN Design Ideas:  Bonnie Baker demonstrates a simple way to add DAC functionality to a microcontroller-based system using only an op amp and two passive components __ Circuit Design by Bonnie Baker, senior applications engineer at Texas Instruments and regular EDN columnist

Voltage Inverter Employs PWM-  07/14/11  EDN Design Ideas:  Use two diodes and two capacitors to generate a negative voltage.  This design idea   describes a circuit employing a small microcontroller-based sensor module with only three connections: 5V dc, an RS-232 transmit-data output, and ground.  A dedicated sing __ Circuit Design by Jeff Wilson, STMicroelectronics, Schaumburg, IL

VU & PPM Audio Metering-  A versatile and useful VU meter circuit, can also operate as a Peak Program Meter __ Designed by Rod Elliott  ESP

Wireless RF PWM Dual Motor Controller-  This is a very simple Wireless RF transmitter circuit that consists of the Holtek HT-12E encoder chip and AM 418MHZ-transmitter module ( WZ-X01, other similar device can be used).  Using the hybrid RF xmit/receive modules make building the RF remote control a lot easy __ Contact info @ wzmicro.com

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