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• 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.

12V high side PWM Motor/Light Controller - scroll down (circuit 6/07)

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) ….(designed by David A. Johnson)

8 Channel PWM Code AVR Controllers - (circuit schematic added 6/07)

A Simple Circuit for Driving MicroController Friendly PWM Generators - Microchip Application Note Published 27-Jun-05  (app note added 2/06)

ABR-42023/ PWM Methods for Expanding CCRL Dimming Range Using the ML4877 or ML4878 - Fairchild Application Notes / (app note added 6/06)

Active Clamp Forward Reference Design - This reference design is an active-clamp forward converter that can deliver up to 24 A of continuous current at 5 V from an input range of 35 V to 75 V. The active-clamp topology with self-driven secondary synchronous MOSFETs allows  device to achieve high efficiencies....(added 6/06)

Active Clamp/reset PWM IC Becomes more versatile - 06/26/03 EDN-Design Ideas: The UCC3580 (www.ti.com), IC1 in Figure 1, is an active-clamp/reset-PWM IC that has all  requisites of a power-supply IC except for current limit. You can use  shutdown pin (16)for this purpose (see  UCC3580 data sheet).....(design idea added 1/05)

Active Clamp/reset PWM IC Becomes more versatile - 06/26/03 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 U.....(design idea added 10/03)

AN268 PWM Amplifier Output Power Calculator - (app note added 6/07)

AN-292: Applications of the LM3524 Pulse-Width-Modulator - National Semiconductor Application Note  (app note added 2/06)

AN-4129/ Green Current Mode PWM Controller FAN7601 - Fairchild Application Notes / (app note added 6/06)

AN538: Using PWM to Generate Analog Output - Microchip Application Note Published 26-Aug-97  (app note added 2/06)

AN539: Frequency & Resolution Options for PWM Outputs - Microchip Application Note Published 26-Aug-97  (app note added 2/06)

AN564: Using the PWM - Microchip Application Note Published 26-Aug-97  (app note added 2/06)

AN-600: Embedding Temperature Information in the ADXL202's PWM Outputs - AN-600 Analog Devices Application Notes  (app note added 6/06)

AN-607: Pulse Width Modulation A/D Conversion Techniques with COP800 Family MicroControllers - National Semiconductor Application Note  (app note added 2/06)

AN654: PWM, a Software Solution using the 16CXXX Devices - Microchip Application Note Published 26-Aug-97  (app note added 2/06)

AN655: D/A Conversion using PWM & R-2r Ladders to Generate Sine & DTMF Waveforms - Microchip Application Note Published 26-Aug-97  (app note added 6/06)

AN771: Suppressing Acoustic Noise in PWM Fan Speed Control Systems - Microchip Application Note Published 27-Jul-04  (app note added 2/06)

AN772: Speed Error in PWM Fan Control Systems TC646, TC647, TC649 - Microchip Application Note Published 27-Jul-04  (app note added 2/06)

AN-815: Variable Range PWM A/D for COP820CJ - National Semiconductor Application Note  (app note added 2/06)

AN-824: Eight Channel Eight Bit PWM Controller - National Semiconductor Application Note  (app note added 2/06)

Analog switch converts 555 timer into Pulse Width Modulator - 02/15/07 EDN-Design Ideas: CMOS switch enhances a PWM oscillator.....(design idea added 9/08)

AN-H23: Avoiding Turn-on Oscillations in HV91 Family PWM ICs - Supertex Semiconductors  (app note added 2/06)

Apex-AN30 PWM Basics - 6/2002, AN30UREVD : 365 Kb (Apex App Note added 08/08/08)

Apex-AN32 PWM Low Pass Filtering - 2/2001, AN32UREVD : 1508 Kb (Apex App Note added 08/08/08)

Apex-AN33 Spice Model & PWM Amplifier Applications - 6/2007, AN33UREVB : 435 Kb (Apex App Note added 08/08/08)

Apex-AN34 PWM Functionality Test - 2/2001, AN34UREVC : 133 Kb (Apex App Note added 08/08/08)

Apex-AN35 PWM AC/DC Power Supply Design - 12/1999, AN35UREVA : 332 Kb (Apex App Note added 08/08/08)

Apex-AN41 Stability & Biasing for PWM Amplifiers - 11/2004, AN41UREVC : 1766 Kb (Apex App Note added 08/08/08)

Applications of the LM3524 Pulse-Width-Modulator - National Semiconductor Application Note  (app note added 2/06)

Avoiding Turn-on Oscillations in HV91 Family PWM ICs - Supertex Semiconductors  (app note added 2/06)