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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E.

Simple Circuit for White LED Night LightThis simple circuit is designed to plug into a standard AC electrical outlet.  It uses four super bright white light emitting diodes (LED) in conjunction with a capacitor coupled full wave rectifier circuit. . . Circuit by David A. Johnson P.E.-July, 2003



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

Simple Circuit controls stepper-motors -  01/08/04 EDN-Design Ideas Stepper motors are useful in many consumer, industrial, and military applications.  Some, such as personal-transportation systems, require precise speed control.  Stepper-motor controllers Design by Noel McNamara, Analog Devices, Limerick, Ireland

Simple Circuit Controls the Rate Of Voltage Change Across a Capacitor or Another LoA - D -  09/22/11  EDN-Design Ideas The output rate of change servos a pass FET.   The circuit in this Design Idea lets you set a well-controlled voltage rate of change, often expressed as the differential dV/dt (instantaneous rate of voltage change over time in volts per second).  You can vary the sensitivity with a potentiometer.  Set the dV/dt from 1V/200 nsec to 1V/3 msec.  The input voltage can range from a few volts to 30V.  Higher-voltage transistors can be used to increase the upper voltage limit.  The circuit precharges a capacitor with a slow and controllable dV/dt to avoid a large inrush current during power-up.  You can also use the circuit to create a high dV/dt for susceptibility testing on other circuits. Design by Fabien Dubois, Ampere Lab, Lyon, France

Simple Circuit DC Motor PWM speed control -  You need a power supply for a project, but only have a DC adapter available, so you can't use my AC power adapter trick (Project 05).  This little project came about because a reader had just this problem, and didn't know what he could do.  This idea will work best with DC adapters having 12V DC or morelower voltages will work, but the dynamic range will not be as good as it could be __ Contact: IQ Technologies

Simple Circuit disconnects loA - D -  02/17/00  EDN-Design Ideas Placing a load-disconnect circuit on the output of a bootstrapped step-up regulator allows the regulator to start with load currents much higher than would otherwise be possible (Figure 1).  During shutdown, the disconnect completely isolates the battery Design by Larry Suppan

Simple Circuit Disconnects Load From Battery -  03/14/96 EDN-Design Ideas To prevent battery damage, the circuit in Figure 1 disconnects the load at a predetermined level of load voltage.  This load voltage, VTRIP, is closely proportional to the battery voltage.  R1 and R2 determine the level of VTRIP  that corresponds to voltage of 1.15V at pin 3 of IC1.  A voltage of 1.15V at pin 3 of IC1 causes the internal comparator to trip.  Thus, VTRIP=1.15(R1+R2)/R1 Design by Michael Keagy, Maxim Integrated Products, Sunnyvale, CA

Simple Circuit Easy Parametric & Graphic Eq's Plus Peaks & Notches -  If you're into playing with tone controls and notch filters to see how they change the sound out of your effects, you will undoubtedly have built several glops of R's, C's and pots, maybe some L's to make up the tone networks.  While this is fun, it's not very flexible.  Sooner or later you might wonder if there is a more general solution to messing with tone controls.   __ Designed by © 1999 R.G. Keen

Simple Circuit ESC -  with optoisolated input

Simple Circuit Flasher Operates Off AC Mains -  06/23/11 EDN-Design Ideas A few components create an illuminated switch.  Looking for a mains switch in the dark is easier if the switch contains a built-in neon or filament miniature lamp.  Adding a small indicator to any mains switch is heLPFul.  It is even better if the indicator flashes.  This circuit makes a simple flasher using only four discrete components (Figure 1).   Design by Noureddine Benabadji, University of Sciences and Technology, Oran, Algeria

Simple Circuit Flashing Light 1 -  This project uses a 3909 IC and a few other parts; power is 1.5 volts DC.   __ Designed by ML Rollins

Simple Circuit Flashing Light 2 -  This project uses parts from Digi-Key __ Designed by ML Rollins

Simple Circuit Flashing Light 3B -  The simplest flashing light circuit in the world! This is the simplest flashing circuit, suitable for tops of tall buildings, smokestacks and water towers __ Designed by ML Rollins

Simple Circuit FM Transmitter with a Single Transistor -  Mini FM transmitters take place as one of the standard circuit types in an amateur electronics fan's beginning steps.  When done right, they provide very clear wireless sound transmission through an ordinary FM radio over a remarkable distance.  I've seen lots of designs through the years, some of them were so simple, some of them were powerful, some of them were hard to build etc.   __ Designed by Kamran Ahmed-UK

Simple Circuit for White LED Night Light -  This simple circuit is designed to plug into a standard AC electrical outlet.  It uses four super bright white light emitting diodes (LED) in conjunction with a capacitor coupled full wave rectifier circuit. . . Circuit by David A. Johnson P.E.-July, 2003

Simple Circuit Infrared Remote Control -  This article will show you how to use the components in our infrared data communications parts KIT.   __ Designed by Reynold's Elec

Simple Circuit LED flasher -  This circuit has a lot going for it.  For one thing, it only consists of two transistors, two capacitors and four resistors.  That also means it consumes very little power.  You can control the flash rate by changing the size of the 100k resistors   (100k makes for a pretty slow rate).  You can also control the duty cycle by using resistors of different values on the two sides __ Designed by Colin Pringle

Simple Circuit light flashing -  This circuit use 2 transistor and some components.  

Simple Circuit Microcontroller-Temperature Measurement Uses Only a Diode & a Capacitor -  12/05/08  EDN-Design Ideas Discharging a capacitor through the reverse leakage of a PN junction allows you to measure ambient temperature.  Using a PN-junction diode for temperature measurement usually depends on its 2‑mV/K temperature  coefficient.  Conventionally, you must amplify and digitize this voltage with an ADC before you can use the value in a microcontroller.  Less well-known is the fact that the reverse current of a PN-junction diode shows a good exponential dependency over temperature; increasing the temperature by approximately 12K doubles the leakage (Figure 1).  An easy way to measure current over such a large range of two to three decades is to charge and discharge a capacitor and measure the time or frequency Design by Andreas Grun

Simple Circuit Night-Light Uses a Photoresistor to Detect Dusk -  12/15/11Design Ideas: You can adjust this battery-powered circuit for different levels. Design by Chau Tran, Analog Devices, Malden, MA

Simple Circuit 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 Design by Jean-Bernard Guiot

Simple Circuit Radio Control from Junk -  Here we are going to make a simple radio controlled device using supplies from your local dumpster.  This project should cost less than a dollar to make.  If you spend more than a dollar on this project, you need to dig more.   __ Designed by sixmhz @ yahoo.com

Simple Circuit safely Deep-discharges NiCd battery  -  04/29/99  EDN-Design Ideas –  NOTE :  Scroll to find this circuit.   Also available athttp://m.eet.com/media/1150682/25098-42999di     Nickel-cadmium (NiCd) batteries can possess an undesirable memory effect due to partial discharges.  The remedy is a complete discharge before charging again. Figure 1a shows a simple circuit that performs this feat.  Design by Jim Hagerman, Science & Technology International, Honolulu, HI

Simple Circuit scheme saves string-light situation -  12/16/04 EDN on Components   As you enter the holiday season with strings of ac-line-powered lights hanging everywhere, do you ever wonder how bulb vendors overcame the frustrating problem of having an entire string go dark when just one of th Design by Bill Schweber

Simple Circuit servo Controller -  This cicuit allows you to test a servo.  The angle of the servo can be set by means of the 10k potmeter.  Perhaps you will not be able to reach all positions with this circuit.  Playing with other

Simple Circuit Servo Controller using 555 Timer -  Servo motors have many uses in everything from robotics to puppetry to photography and beyond.  These little motors can position their output shaft to any position on command and hold that position.  Most servos have a range of motion to about 210 degrees and thankfully are very easy to control with a simple circuit such as the one presented here.  Using just a 555 timer and a few support components this circuit can control a servo through it's full rotation based on the position of a pot.  This circuit was originally published in the Think Tank column of the October 1995 issue of Popular Electronics. __ Designed by Aaron Cake

Simple Circuit Servo Tester -  This is a simple servo tester which will comprehensively test the capabilities of almost any modern servo. It has two pushbuttons, CENTRE and SWEEP and a potentiometer which works as follows: __ Designed by Edward M

Simple Circuit Smoothly Drives Stepper Motors -  05/28/09  EDN-Design Ideas Adding an analog switch make the motor bidirectionalThe circuit in This design idea     drives low-power, unipolar stepper motors using only a shift register, a few resistors, and low-power transistors.  Adding an inexpensive 4053 an Design by Uwe Schüler, Institute of Physiology, Tübingen, Germany

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.  Activating sequence: [code:1:7492cb9d88]+-------------+---------------+ | Inputs |Coils Energised| |-------------+ | | D0 D1 |

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.

Simple Circuit stepper Motor Controller -  This design allows for very precise control of the motor: by proper pulsing, it can be turned in very accurate steps of set degree increments (for example, two-degree increments, half-degree increments, etc.).  They are used in printers, disk drives, and other devices where precise positioning of the motor is necessary.  There are two basic types of stepper motors, unipolar steppers and bipolar steppers

Simple Circuit stepper Motor driver for PC parallel port -  A stepper motor has four coils.  The direction of rotation (clockwise or anti-clockwise) depends on the order in which the currents supplied to the coils are switched on.  If you use the motors type 55SI-25 DAYA, having a connector as shown below,  __ Designed by © David Hoult

Simple Circuit 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

Simple Circuit Surround Processor -  Simple Surround Processor.  This is built with only conventional parts, and digital delay block, too.  So it is very easy to build.   __ Designed by The Electronic Lives Manufacturing-presented Chan

Simple Circuit 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

Simple Circuit temperature regulated FAN speed controller -  This regulator uses a P-FET to change the positive supply voltage to a FAN an NTC resistor mounted on the device that needs cooling will change the fan speed, the temperature on the heat sink will therefore be constant, while the FAN speed will change, depending on power disipated __ Designed by OZ2CPU Thomas  Denmark

Simple Circuit Tester Checks Christmas-Tree Lights -  12/23/99 EDN-Design Ideas Why is it that you always test 48 bulbs before you find the bad one in a 50-light string? This simple circuit allows you to divide and conquer, greatly reducing the time it takes to find the bad bulb. Design by William Dias, Brown & Sharpe, North Kingstown, RI

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