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

 

Last Updated: December 31, 2017 06:44 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

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

 

 
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

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PWM Circuits:  # - G     H - O     P - S     T - Z


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