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Control Circuits

 
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Last Updated: November 21, 2017 05:45 AM

Circuits Designed by Dave Johnson, P.E.

Pushbutton Activates Service Request BeeperA single press of a pushbutton switch turns on a beeper for one second but can’t be activated again for 60 seconds.. . . Circuit by Dave Johnson P.E.-September, 2005

Pushbutton Controlled Up/Down Ramping LightThere are times when you want a lamp to gradually change from dark to light and from light to dark, with each push of a pushbutton switch.  The circuit below performs this control function using a flip/flop and a classic pulse width modulation or PWM. . . Circuit by David Johnson P.E.-March, 2009

PWM Circuit for Motor Speed ControlSometimes 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 A. Johnson P.E.-December, 2007

PWM Motor Controller uses a 555 TimerUsing 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 Dave Johnson P.E.-February, 2007


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

Provide 70 DB of ACG -  02/02/12  EDN-Design Ideas A comparator autoranges to ensure that the automatic-gain-control section sees a signal between −60 and −25 dBm, keeping the FET in its linear region.  The circuit diagrammed in the figure provIdeas a 70-dB automatic-gain-control range for input voltages of −60 to +10 dBm over a bandwidth of 55 Hz to 15 kHz.  The worst-case distortion is 3%, but distortion typically measures less than 1% in the 100-Hz to 10-kHz range.   __ Circuit Design by Ben Segal, Telecommunications Technology, Sunnyvale, CA

Provide Bidirectional Variable Speed Motor-Control -  05/16/02 EDN-Design Ideas During the development of systems that include small motors, a simple, bidirectional motor controller with speed adjustment may be heLPFul.  Figure 1 shows such a controller.  The circuit uses everyday components whose tolerances and ratings are unimportant as long as they sustain the required voltage, current, and power __ Circuit Design by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland

Provide Brownout Control of 80c31 -  08/19/99EDN-Design Ideas In the reset and watchdog-timer circuit in Figure 1, IC1 is a 74HC14 Schmitt-trigger inverter that, with R1 and C1, acts as an astable oscillator.  The circuit provIdeas an active-high reset for an 80C31 µC.  The watchdog trigger (W __ Circuit Design by N Kannan, Mediatronix, Pappanamcode, India

Provide Class D Motor Control -  05/01/03  EDN-Design Ideas Class D audio amplifiers provide a dual benefit for battery-powered portable devices.  They enhance battery life, and they produce much less power dissipation than do their linear cousins.  Those features make Class D amplifiers ideal __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

Provide efficient fan-speed control -  03/04/04  EDN-Design Ideas As Moore's Law plunges us into the realm of multigigahertz processors and PCs with gigabytes of RAM, engineers face the task of removing the heat that these state-of-the-art components produce.  Cooling such systems poses a dilemma.   __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

Provide More Accurate Multiplication -  12/15/11 EDN-Design Ideas Convert into and out of the sampled-data domain to get an accurate multiplication.  Common analog multiplying devices employ methods using transistor parameters.  Precise versions of these devices use the logarithm method of multiplication.  This method involves the addition of logarithms and an exponential conversion (Reference 1).  Using these methods, you can achieve a minimal error of ±0.1%.  This Design Idea reduces the error, employs readily available standard components, and maintains the correct voltage scale.   __ Circuit Design by Yakov Velikson, Lexington, MA

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

Provides Efficient Fan-Speed Control -  03/04/04  EDN-Design Ideas As Moore's Law plunges us into the realm of multigigahertz processors and PCs with gigabytes of RAM, engineers face the task of removing the heat that these state-of-the-art components produce.  Cooling such systems poses a dilemma.   __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

Provides Laser-Diode Control -  09/19/02  EDN-Design Ideas Laser diodes are sensitive to ESD, rapid turn-on currents, and overvoltage conditions.  To address those problems, the simple laser-diode controller in Figure 1 has several functions.  The first part of the circuit comprises an 8.2V  __ Circuit Design by Michael Fisch, Agere Systems, Longmont, CO

Provides Motor Feed Control -  07/25/02 EDN-Design Ideas Linear power driver works from single supplyBecause we needed a small grinding machine, we modified an old milling machine that lacked a control system.  The table of the grinding machine needed only to move back and forth with __ Circuit Design by Jean-Bernard Guiot

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 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 Modulators -  generating PWM waveform is extremely simple with the circuits shown in this page __ 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 knowthe 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 Adjuster Reverses Servo Motor -  03/17/94 EDN-Design Ideas Typical remote-control systems and robotics applications use standard R/C servos, which often require a reversal of the direction of rotation.  Since varying the input signal's pulse width between 1 and 2 msec controls the servo's output position, a circuit that adjusts the pulse width __ Circuit Design by Joe Utasi, Jomar Products Corp, Cincinnati, OH

Pulsing Third Brake Light -  The schematic consists of two 555 timer/oscillators in a dual timer configuration both setup in astable mode.  When power is applied via the brake pedal, the brake light driver Q1 is switched on via the low-output pin 3 of IC2, and timer IC1 begins its timing cycle.  With the output on pin 3 going high, inhibiting IC2's pin 2 (trigger) via D2, charge current begins to move through R3, R4 and C2. __ Designed by Tony van Roon  VA3AVR

Pulsing third Brake lite for cars -  Several years ago these flashers were introduced in the automotive industry as part of the third brake light and contained strobe lights   (and strobing continuously for the duration of pressing the break pedal) but got abandoned almost immediately sometime later because of the 'strobe' effect it has on some people.  This circuit has become obsolet since much better circuits are available these days without the 'lag' in between brakes caused by R4 and C3.  One of the circuits is listed below __ Designed by Tony van Roon  VA3AVR

Push Button Motor Control -  This circuit uses solid state switching (transistors) to control direction of a DC motor.  You have precise control of the movement of the motor, and an indication of direction provided by LED's.   __ Designed by Andy Collison

Push-bike Light -  Automatic switch-on when it gets dark; 6V or 3V battery operation __ Contact: Flavio Dellepiane, fladello @ tin.it

Pushbutton Activates Service Request Beeper -  A single press of a pushbutton switch turns on a beeper for one second but can’t be activated again for 60 seconds.. . . Circuit by Dave Johnson P.E.-September, 2005

Pushbutton Control for Single-Phase Appliances -  This circuit lets you switch off and switch on a single-phase appliance using two separate push switches.  Such an arrangement is common for industrial motors (mostly 3-phase) where an isolation is...__ Electronics Projects for You

Pushbutton Controlled Up/Down Ramping Light -  There are times when you want a lamp to gradually change from dark to light and from light to dark, with each push of a pushbutton switch.  The circuit below performs this control function using a flip/flop and a classic pulse width modulation or PWM. . . Circuit by David Johnson P.E.-March, 2009

Pushbutton on/off control for battery-powered Device, with automatic turn-on when the Device is plugged in -  This circuit shows a typical LTC2955-1 application for a handheld device.  The 3.6V supply is produced directly from the handheld’s battery; the 12V secondary supply comes from a wall adapter.  Both the 3.6V and 12V inputs are connected to the LT3060 regulator input via diode-OR so that either supply can power the system.  The __ Linear Technology/Analog Devices App Note, Jun 29th 2012

Pushbutton switch controls power supply & µC -  09/25/97 EDN-Design Ideas  Switching handheld units on and off with a pushbutton switch is a desirable feature.  Thus, switching-regulator/ controller ICs for battery-powered applications provide a logic input to switch the device to a shutdown mode.  This type of shutdown pin can require additional components __ Circuit Design by Greg Dittmer, Linear Technology Corp, Milpitas, CA

Put Coin & Draw Power -  Built on the lines of payphones, here is an automatic coin collection device for payloads like lamps and air-conditioners to be used on a private electrical line.  It is useful for...__ Electronics Projects for You

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 A. 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 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 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 Dave Johnson P.E.-February, 2007

PWM Motor Speed Controller / DC Light Dimmer -  A pulse width modulator (PWM) is a device that may be used as an efficient light dimmer or DC motor speed controller.  The circuit described here is for a general purpose device that can control DC devices which draw up to a few amps of current.  The circuit may be used in either 12 or 24 Volt systems with only a few minor wiring changes __ Designed by Radio LocMan

PWM Motor Speed Controller / DC Light Dimmer -  A pulse width modulator (PWM) is a device that may be used as an efficient light dimmer or DC motor speed controller.  The circuit described here is for a general purpose device that can control DC devices which draw up to a few amps of __ Designed by G. Forrest Cook

PWM Motor Speed Controller / DC Light Dimmer -  A pulse width modulator (PWM) is a device that may be used as an efficient light dimmer or DC motor speed controller.  The circuit described here is for a general purpose device that can control DC devices which draw up to a few amps of current.  The circuit may be used in either 12 or 24 Volt systems with only a few minor wiring changes.  This device has been used to control the brightness of an automotive tail lamp and as a motor speed control for small DC fans of the type used in computer power supplies. __ Designed by G. Forrest Cook

PWM Motor Speed Controller/DC Light Dimmer -  This circuit will work as a DC lamp dimmer, small motor controller, and even as a small heater controller.  It would make a great speed control for a solar powered electric train.  The circuit has been tried with a 5 Amp electric motor using and IRFZ34N FET and worked ok, D1 may need to be replaced with a faster and higher current diode with some motors.  The circuit should work in applications such as a bicycle motor drive system, if you experiment with this, be sure to include an easily accessible emergency power disconnect switch in case the FET shorts out and leaves the circuit full-on. __ Designed by 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 __ Designed by G. Forrest Cook

PWM Speed Control -  includes theory and some example circuits __ Designed by Richard Torrens

PWM-Based Motor Speed Control Simulation using Ltspice -  Pulse-width modulation (PWM) is one of the oldest and widely used techniques of controlling electrical motors.  To control the speed of the motor, the average value of the PWM pulse...__ Electronics Projects for You

PWM-Based Speed Control for DC Motors -  There are several methods for controlling the speed of DC motors.  One simple method is to add series resistance using a rheostat.  As considerable power is consumed in the rheostat, this...__ Electronics Projects for You

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Control Circuits:   #'s - A       B - C       D - G        H - L       M - P        Q - S        T - U        V - Z


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