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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.

Super Bright 3v Powered LED FlasherI have posted several kinds of LED flashers over the years.   This is yet one more flasher, designed to flash any high power LED of any color.  It hits the LED with a 25ms 250ma pulse once every 2 seconds.   This works out to an average current about 3ma.  It. . . Circuit by David Johnson P.E.-April, 2009

Switch Detects Audio SignalThis circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.    It could be used to turn on a relay, routing the signal to were it is needed.. . . Circuit by David Johnson P.E.-July, 2006

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

Strain Meter -  This strain meter shows whether the strain is compressive (reducing the length) or tensile (increasing the length) when an object such as a strut on a crane changes its shape.__ Electronics Projects for You

Street Light Controller -  Two of the problems commonly associated with street lights are false triggering due to slight variation in the intensity of ambient light and no control over switching action.  Here is a...__ Electronics Projects for You

Strobe from Flash -  After using a disposable camera, you can build a strobe light (flashing light) with one simple modification.  (6/02/2006)  __ Designed by Jose Pino

Strobe Light -  A xenon flash tube is a triggered gas discharge device.  A voltage may be impressed across the tube and it will not conduct until the xenon gas is ionised by an external high voltage (typically 3 to 5kV).  Once triggered, the gas becomes a very low impedance, and discharges the storage capacitors in about 1ms (this varies considerably, but this figure is fine for basic calculations)  __ Designed by Rod Elliott  ESP

Strobe Light -  Disco anyone? Actually, this strobe serves a much more useful purpose then making it look cool when you dance in the dark.  You can use it to view fast moving objects, look for craks in PC boards (hold the strobe on the trace side of the board and look from the component side) , and it is a great attention getter in a store window __ Designed by Aaron Cake

Strobe Light 12 Volt Coil Powered -  This circuit will give provide a Good Strobe Effect for a variety of
Portable Uses.  Nominal current draw is "up to about" 1 amp at 12 volts.  Depending on value of capacitor on pin 2 of the 555 and the particular choke that is used.  The .01 cap on pin 2 of the 555 may be slightly changed in value to optomize the output drive to the 22 mfd capacitor.   __ Designed by G.L. Chemelec

Strobe Trigger -  These pictures are scenes frozen by a flash unit that is triggered by the action being recorded.  They were made by setting up a shot, opening the camera shutter using its "bulb" setting, and carrying out some action that opened or closed a circuit to trigger the flash.  The balloon pictures were taken by triggering the flash when the balloon began to shrink after being popped.  In most cases the balloon had a strip of foil attached to it with probes pressed against it on two sides, with a circuit interrupted when the foil pulled away from the probes __ Designed by John DuBois

Strobex Schematic -  Schematic only for a Variable Intensity Variable Speed Stroboscop, no circuit description given.   __ Designed by Samuel M. Goldwasser

Strobo Control -  Remote controller for professional lighting system stroboscope, controls the flashing speed.   __ Designed by Tomi Engdahl

Strobo Disco Light using Standard Tube Lamp (TL) -  Using a standard fluorescent tube lamp (TL), you can make your own disco light, similar to a stroboscope light.  You can even use a half-broken lamp, which one side of the heating filaments has broken.  This circuit use only one side heating filament inside the tube.  Look at the circuit’s schematic below.

Stroboscope -  The 220v supply is rectified and then used to charge the two 3µ* capacitors.  The 1µ capacitor also charges (more slowly) through the 150k resistor and 1M variable resistor.  When the voltage across the 1µ capacitor is high enough to cause the diacs to conduct, the thyristor is triggered.  This produces a high voltage "pulse" at the secondary of the transformer.  This pulse causes the tube to conduct and a flash of light is produced.  __ Acknowledgements The stroboscope was taken from an excellent French electronics magazine  sadly, no longer published called "Elex"

Stroboscope triggers -  This circuit typically uses a voltage around 300 volts for the main high voltage supply and needs a low voltage supply of typically 6 to 15 volts.   __ Designed by Don Klipstein

Subwoofer Controller -  Adding a subwoofer to your home theatre or hifi system is the easiest way to extend the bass response.  A relatively small speaker system driven by a big amplifier can give heaps of bass while not taking up a lot of space.  This new Subwoofer Controller has all the features you could want, including low and high pass filters, parametric equaliser and auto-turn on.__ SiliconChip

Subwoofer Equaliser -  The Linkwitz transform circuit is a hugely flexible way to equalize the bottom end of a sealed loudspeaker enclosure.  A speaker that is corrected using this method is flat from below resonance to the upper limit of the selected driver.  The low frequency roll off point is determined by the parameters of the transform circuit __ Designed by Rod Elliott  ESP

Sump Pump Controller -  Having a reliable system to pump out a sump pit is essential as mistakes and failures can lead to serious flooding and enormous expense.  In our article Sump Pump Control System we introduced a selection of electronic solutions to the following problems __ Designed by REUK-Renewable Energy UK website

Sunrise Lamp using 120VAC 60 Watt Lamp -  In this circuit, a 120VAC lamp is slowly illuminated over a approximate 20 minute period.  The bridge rectifier supplies 120 DC to the MOSFET and 60 watt lamp.  A 6.2K, 5 watt resistor and zener diode is used to drop the voltage to 12 volts DC for the circuit power.  The bridge rectifier should be rated at 200 volts and __ Designed by Bill Bowden

Sunset Lamp -  LDR-based automatic lights flicker due to the change in light intensity at dawn and dusk.  So compact fluorescent lamps (CFLs) are unsuitable in such circuits as flickering may damage the electronic...__ Electronics Projects for You

Super Bright 3v Powered LED Flasher -  I have posted several kinds of LED flashers over the years.   This is yet one more flasher, designed to flash any high power LED of any color.  It hits the LED with a 25ms 250ma pulse once every 2 seconds.   This works out to an average current about 3ma.  It. . . Circuit by David Johnson P.E.-April, 2009

Super Remote -  Using a PIC12F683 and a few transistors, it is theoretically possible to boost the power to a standard 433 MHz remote transmitter module.  (Note hypothetical image at right)  __ Designed by Luhan Monat-Mesa Arizona

Super Simple Circuit Flasher -  File contains several designs, please scroll to find this circuit.  Here is a simple flasher circuit that uses no resistors! However, it relies on leakage in the base of the PNP germanium transistor and only some will work; be prepared to try a few.  If you add a 100k resistor from the base to the collector of the PNP, the circuit will work with most germanium transistors and will work down to 1 VDC! The NPN should be a silicon type.  The 100 uF may be replaced with a 22uF in series with a 5k resistor and it would be a good idea to add 39 ohms in series with the base of the NPN (but then the circuit starts to lose its charming simplicity).   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Super Simple Circuit Stepper Motor Controller -  The circuit shown above can be used to control a unipolar stepper motor which has FOUR coils (I’ve swiped it off an old fax machine).  The above circuit can be for a motor current of up to about 500mA per winding with suitable heat sinks for the SL100.  For higher currents power transistors like 2N3055 can be used as darlington pair along with SL100.  The diodes are used to protect the transistor from transients.

Supercapacitor Energy Storage System for Data Backup -  This circuit shows a supercapacitor-based power backup system using the LTC3625 supercapacitor charger, an automatic power crossover switch using the LTC4412 PowerPath controller and an LTM4616 dual output μModule DC/ DC converter.  __ Linear Technology/Analog Devices App Note, Mar 16th 2011

Supercap-Based Power Ride-Through Maximizes Run Time using an Energy Scavenging Scheme -  This circuit shows a complete 3.3 V/200mA ride-through application that maximizes the amount of power extracted from the supercap to support the load.  The main components of the ride-through application includes the LTC4425 complete 2A supercapacitor charger to clamp the individual cell voltages and ensure that the cells do__ Linear Technology/Analog Devices App Note, Mar 16th 2011

Surround Sound Decoder -  This surround-sound decoder is based on the "Hafler" principle, first discovered by David Hafler sometime in the early 1970s.  The original idea was to connect a pair of speakers as shown in Figure 1, for use as the rear speakers in the surround setup __ Designed by Rod Elliott  ESP

Switch controls digital potentiometer -  02/27/02  EDN-Design Ideas The control of electronic potentiometers in most today's applications comes from controller-generated signals.  However, a significant number of applications exist that require adjustments using manual, front-panel controls.  The circuit in Figure 1 uses one IC, one switch, and 10 discrete components __ Circuit Design by Chuck Wojslaw and Gary M Craig, Catalyst Semiconductor, Sunnyvale, CA

Switch controls lights -  04/07/11  EDN-Design Ideas Cities and towns worldwide are considering and installing LED streetlights to help save electric energy, reduce costs, protect the environment, and improve lighting for their citizens.  Despite this trend, the lamps’ turn-on/turn-off time control is receiv __ Circuit Design by C Castro-Miguens, University of Vigo, Spain, and JB Castro-Miguens, Cesinel, Madrid, Spain; Edited by Martin Rowe and Fran Granville

Switch Detects Audio Signal -  This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.    It could be used to turn on a relay, routing the signal to were it is needed.. . . Circuit by David Johnson P.E.-July, 2006

Switched capacitor IC controls feedback loop -  02/17/00 EDN-Design Ideas You can implement a simple control loop with a constant setpoint over a wide range of control by using a switched-capacitor filter.  The circuit controls motor speed over 1 to 200 Hz or 60 to 12, 000 rpm.  In Figu __ Circuit Design by Dave Sargent, IBM Research, San Jose, CA

Switching-regulator generates fast pulses -  04/13/06  EDN-Design Ideas Switching-regulator-controller ICs can deliver gate-drive pulses with rise and fall times of less than 2 nsec, making them ideal candidates for laboratory pulse-generators __ Circuit Design by Mitchell Lee, Linear Technology Corp

Sync Separator Includes AGC -  05/11/95 EDN-Design Ideas This sync separation circuit has a gain-control circuit that helps to stabilize the sync-separation function __ Circuit Design by Dana Romero, Salt Lake City, UT-- 05/11/95

System Monitor with Instrumentation-Grade Accuracy Used to Measure Relative Humidity -  A psychrometer is a type of hygrometer, a device that measures relative humidity.  It uses two thermometers, one dry (dry bulb) and one covered in a fabric saturated with distilled water (wet bulb).  Air is passed over both thermometers, either by a fan or by swinging the instrument, as in a sling psychrometer.  A psychrometric __ Linear Technology/Analog Devices App Note, Jan 30th 2012

System Monitors multiple temperatures, controls fan speed -  10/12/00 EDN-Design Ideas The block diagram in Figure 1 represents a complete remote-temperature-sensing and fan-control system.  The system uses an Analog Devices temperature-monitor and fan-control ASIC and a PIC16C84 µC from Microchip Technology.  The ADM1022 allows you to measure the local temperature and two remote temperatures within a system.  An on-chip, 8-bit DAC controls the speed of a cooling fan in response to the measured temperature.    __ Circuit Design by David Hanrahan, Analog Devices Inc, Limerick, Ireland

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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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