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Control Circuits

 
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Last Updated: October 24, 2017 02:54 PM

Circuits Designed by Dave Johnson, P.E.

AC Current Controls Hour MeterMany systems require routine maintenance based on machine operation time.  The circuit below is a simple way to turn on a hour meter whenever AC power is supplied to the machine.  An inexpensive snap-on current transformer from Magnetics Inc, is used to. . . Circuit by David A. Johnson P.E.-February, 2010

AC Line Powered LED FlasherSome of the latest LEDs are amazing.  They can produce a surprising amount of light with very little current.  In the light flasher application shown below I take advantage of a nice surface mounted LED from King Bright.  This flasher circuit draws only about 3ua of average current from the AC power line to flash this green LED.  This flasher might be used as a power indicator light . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2008

AC Line Under/Over Voltage AlarmPower lines, which deviate much beyond normal voltages can damage expensive electronic equipment.  The circuit below sounds an alarm whenever the line voltage is higher or lower than normal.  I set the alarm limits at about +-15% from standard levels . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2009

AC Power Line High/Low Voltage TesterIf you wish to test a line-powered device under both a 15% high and a 15% low voltage condition, you can use the circuit below.  The circuit uses an 18v transformer with a 3 amp rating.  A double pole, double throw toggle switch then switches in the. . . Circuit by David A. Johnson P.E.-March, 2010

AC Power Loss AlarmIve been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter   (GFI) module.  Every now and then, the GFI trips, leaving me without hot water. . . Circuit by David A. Johnson P.E.-March, 2009


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

A Voice Controlled LED Light Show using a VRStamp -  A voice controlled LED light show.  Train your board with your voice, then control the LED animation by saying commands!   This project is fitted to the mikroC RSC-4x compiler small memory model : no mikroC licence is needed, just to show the power of the demo version!__ Bruno Gavand

A worked Stepping Motor Example -  Perhaps some of the most commonly available stepping motors, for the experimenter, are the head positioning motors from old diskette drives.  These can be found at electronics swap meets, in computer surplus outlets, and even in trash dumpsters.  In addition to a stepper, a typical full-height 5.25 inch disk drive includes a 12 volt DC motor with tachometer and motor control circuit board, two microswitches, and a matched LED-photosensor pair   (schematic design 6/06)  __ Designed by Douglas W. Jones

AC Current Controls Hour Meter -  Many systems require routine maintenance based on machine operation time.  The circuit below is a simple way to turn on a hour meter whenever AC power is supplied to the machine.  An inexpensive snap-on current transformer from Magnetics Inc, is used to. . . Circuit by David A. Johnson P.E.-February, 2010

AC Line Powered LED Flasher -  Some of the latest LEDs are amazing.  They can produce a surprising amount of light with very little current.  In the light flasher application shown below I take advantage of a nice surface mounted LED from King Bright.  This flasher circuit draws only about 3ua of average current from the AC power line to flash this green LED.  This flasher might be used as a power indicator light . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2008

AC Line Powered LED Strings -  This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.    This hobby circuit was designed by Ken Schultz.   __ Designed by Ken Schultz, drawn Dave Johnson 12.18.2004 May, 2005

AC Line Under/Over Voltage Alarm -  Power lines, which deviate much beyond normal voltages can damage expensive electronic equipment.  The circuit below sounds an alarm whenever the line voltage is higher or lower than normal.  I set the alarm limits at about +-15% from standard levels . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2009

AC Motor Speed Controller -  This AC motor speed controller can handle most universal type   (brushed) AC motors and other loads up to about 250W.  It works in much the same was a light dimmer circuit; by chopping part of the AC waveform off to effectively control voltage.  Because of this functionality, the circuit will work for a wide variety of loads including incandescent light bulbs, heating elements, brushed AC motors and some transformers.   __ Designed by Aaron Cake

AC Power Line Clock Controller using AT89C2051 -  The Clock Controller V1.1was designed to be an exemplary of using 'C' language to control timer0interrupt, 7-segment LED and keypad scanning.  It provides 1-bit sink currentdriving output, for driving a relay, opto-TRIAC, say.  Many projects requiring7-segment display and keypad interfacing may get the idea from the Clockcircuit and software.   __ Designed by Wichit Sirichote

AC Power Line High/Low Voltage Tester -  If you wish to test a line-powered device under both a 15% high and a 15% low voltage condition, you can use the circuit below.  The circuit uses an 18v transformer with a 3 amp rating.  A double pole, double throw toggle switch then switches in the. . . Circuit by David A. Johnson P.E.-March, 2010

AC Power Loss Alarm -  Ive been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter   (GFI) module.  Every now and then, the GFI trips, leaving me without hot water. . . Circuit by David A. Johnson P.E.-March, 2009

AC power Monitor uses remote sensing -  04/26/01 EDN-Design Ideas The detection circuit in the Design Ideas"Circuit monitors ac-power loss"   (EDN , Nov 24, 1999, pg 172) requires a physical connection with the mains to sense the power loss.  The circuit in Figure 1 senses the power loss through the radiated power-line signal __ Circuit Design by Sanjay R Chendvankar, Tata Institute of Fundamental Research, Colaba, Mumbai, India

AC power supply -  I have done a lot of work with valves in recent years.  For me valves have many advantages, least of all the price; since they are now "obsolete" it is quite easy to get hold of them for next to nothing at rally's and junk sales.  I recently purchased a couple of hundred battery valves for less than SEK1   (GB0.10 US$0.15) each.   __ Designed by Harry Lythall-SM0VPO

AC Servo Motor Windmill -  A windmill built around a 3 phase servo motor from an old welding robot.  

Accent Lights Are a Crowning Achievement -  23-Nov-09 -Design News:   As a way to set the mood in his family room, when he remodeled Joe Peck put multi-color LEDs behind the crown molding.  The major circuit uses a microcontroller and LED drivers located in a closet, and a small circuit board at each room corner to connect to red-green-blue LEDs.  Perhaps Joe's lights __ Gadget Freak-Case #153

Accomodating Offset IF Filters -  Digitally synthesized FM tuners normally use ceramic IF filters centered at 10.7 MHz. But the characteristics of individual filters vary. Murata specifies filter center frequency as 10.67 to 10.73 MHz. Outlier filters may make a tuner more susceptible to interference on one side of channel center than the other.  __ Designed by Brian Beezley K6STI

Achieve Precision Temperature Control with TEC Seebeck-Voltage Sampling -  27-Nov-08 EDN-Design Ideas By periodically setting the TEC's drive to zero, a storage capacitor samples and holds the Seebeck voltage __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

Achieve Simple Circuit IR data transmission from a PCs serial port -  10/11/07 EDN-Design Ideas By transmitting appropriate hex values from a PC's serial port to a pair of IR LEDs, a remote-control IR receiver can enable 38.4-kHz data transmission __ Circuit Design by Andreas Grn, Wedemark, Germany

AC-power your without a transformer -  07/17/13  EDN-Design Ideas Editor's Note: Here's another take on the transformerless AC line power supply, which finds use in some well-insulated, low-power devices.  Our technical reviewer pointed out that Cac should be an X-rated safety type, and I think we'd both feel better if the ground symbol wasn't there!  SMPS circuits offer an efficient way to reduce AC from a mains source to any desired level for powering low-voltage circuits, though this comes at the cost of components such as control ICs, switching transistors, inductors, etc.  Figure 1 shows a simple way you can use more common components to step-down and regulate the AC mains to the desired low DC voltage.   __ Circuit Design by Raju Baddi

Active load handles high voltages -  EDN-Design Ideas 02/25/2016    This electronic load design presses an electric kettle into service as a power resistor __ Circuit Design by Gheorghe Plasoianu

Active pullup/pulldown network saves watts -  02/17/05  EDN-Design Ideas The control circuit in Figure 1 presents a relatively low input resistance and thus imposes a low value on external pulldown resistor R1 to provide the desired low-level input voltage.  In turn, R1 wastes power by drawing a relative __ Circuit Design by JB Guiot, DCS Dental AG, Allschwil, Switzerland

Active Subwoofer & Controller -  Designed to operate a sub-woofer driver below its resonant frequency __ Designed by Rod Elliott  ESP

ActiveX control brings bit manipulation to Windows -  05/25/00 EDN-Design Ideas Nothing compares with the C language for working with bits.  C provIdeas a rich set of signed and unsigned number formats, along with many intrinsic bit-manipulation operators.  However, most of the popular rapid-application-development Windows languages __ Circuit Design by Steve Hageman, Agilent Technologies, Santa Rosa, CA

Adaptive rotary encoder distinguishes fine from coarse -  EDN-Design Ideas 06/20/2013    Need a rotary panel control that automatically switches between fine and coarse adjustment? It's here __ Circuit Design by Anthony Smith

Adaptive Windscreen Wiper Control -  This is easy to install to the usual system.     (Not for instance MAZDA 626, where the external connections  are literally avoided.)   You have to find a wire which has a voltage in position '1' and then you cut that wire.  After that You install the "ADAPWIPE" between the break of wire just like the circuits diagram  ADAPWIPE.ISS it shows.  (Immediately after the switch!)   __ Mark Harris 2008

ADC controls multiple stepper Motors -  09/14/00 EDN-Design Ideas Typical stepper-motor control circuits use either logic gates and flip-flops or shift registers to generate the proper sequences of binary codes that produce bidirectional stepper-motor movement.  A conventional stepper-motor-control circuit uses a square-wave generato __ Circuit Design by K Suresh, Indira Gandhi Centre for Atomic Research, Kalpakkam, India

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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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