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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E.

Mechanical_Underground_Gate_Opener -  Provide power to mechanical gates located opposite ends of a looping branch tunnel.  The gate was required to open and close perhaps only 2 times each month. The gates were set to open and then close again at ten minutes intervals.  Solution:  Use a wind generator.  . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 15 Jan 2011

Micro Power Over-Temperature AlarmThe circuit is powered for years by a single 3 volt lithium battery.  It sounds an alarm when the temperature exceeds a certain point.  With some minor changes the circuit could also be configured for an under temperature (freeze) alarm.  The circuit uses a. . . Circuit by David A. Johnson P.E.-June, 2000

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

Mad idea for a blacklight strobe -  CAUTIONMay be both hard on your eyes and a bit disappointing __ Designed by Don Klipstein

Magic Lamp -  No, its not Aladdin's lamp with a genie inside.  This magic lamp appears to be an ordinary frosted light bulb with a rather unusual characteristic.  Whenever your finger is touched across the base threads and center contact the lamp magically lights! Without wires! It is a most effective illusion if you don't make a big production, "Hey! Check out this magic lamp!", but instead casually remove the bulb from a package of new bulbs and pretend to not notice when it lights.  When your victim gasps and grabs the bulb for further investigation just explain away the flash as some sort of static electricity effect and act indifferent. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Magic Lights -  The circuit as shown in the figure employs 14 bi-colour (red and green) LEDs having three terminals each.  Different dancing colour patterns are produced using this circuit since each LED can...__ Electronics Projects for You

Magnetic Longwire Balun (MLB) also usable for dipoles and homemade RF choke -  Ham RadioBALUN, TUNERSSchematic __ Designed by Guy Roels ON6MU

Magnetic longwire balun and VHF-splitter -  Ham RadioBALUN, TUNERSSchematic __ Designed by Guy Roels ON6MU

Mains 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

Mains Remote Switch -  This compact design forms a remotely operated switch that receives its control signal via the mains voltage.  The switch is operated using the ‘mains remote transmitter’ described elsewhere in this issue.  With this transmitter, a switch should be connected between pins 1 and 2 of K1.  Depending on the application, this must be either a

Mains Remote-Alert -  Remotely-operates a Beeper and/or a LED via mains supply line __ Contact: IQ Technologies

Mains Synchronization Has Two Separate Outputs for Each Half-Period -  03/22/13  EDN-Design Ideas Generate independent short pulses at positive- and negative-going AC mains zero crossings.  Often a measurement of weak signals has to be performed in the presence of strong interference from the ac power mains.  If the interfering signal cannot be filtered out, then you can still obtain a clean result by making two consecutive measurements separated in time by an odd number of half-periods of the mains and calculating the average of the two measurements.  The interfering signals have opposite polarities in consecutive measurements, and averaging cancels them out.  If you average several consecutive pairs of measurements, the results will improve still further.   Design by Dusan Ponikvar

Make a Simple Circuit PC-Based frequency meter  -  04/29/99  EDN-Design Ideas –  NOTE :  Scroll to find this circuit.   A simple, low cost, and precision frequency meter uses only two pins of a pc parallel port (Figure 1). The TTL-level periodic input signal with frequency fIN connects to the ACK pin of LPT1. Design by Radovan Stojanovic, University of Patras, Patras, Greece

Making a bistable from a normal relay, based on coil hysteresis -  This simple circuit turns on and off a coil with a momentary switch, then it works as a bistable relay.  The circuit is supplied by 12 Volt DC and drives a 5 Volt -125 ohm coil.  When the button is pressed both transistors switch on, but the coil takes a voltage of about 2,5 Volt, so it keeps off.  By releasing the button the Q2 transistor keeps on for a bit due to the capacitor; since the coil takes almost 5 Volt the relay switches on and closes the circuit between the pins 11 and 14. __ Designed by Andrea-Central Italy

Making your own RS-60E3 Remote Control for Canon EOS cameras -  Welcome to, ashamedly, the most popular page on my website.  I'm not really sure why, but I guess people like these do-it-yourself projects.  Promise me you'll go look at pretty pictures after this, okay? __ Designed by Markus Wandel

Manage power-up sequencing with this -  31-Oct-02 EDN-Design Ideas Power sequencing poses a unique problem in power management.  Because improper sequencing may cause damage to many types of processors, power-up sequencing of these devices is critical.  Devices that may require power-up sequencing control include FPGAs, ASICs, and DSP chips.  These devices can require tracking I/O and core voltages Design by Martin Galinski

Mark 1/1A -  This circuit is used to relay signals from an Infra Red remote control in one room to an IR controlled appliance in another room.   __ Designed by Andy Collison

Marx Flasher -  File contains several designs, please scroll to find this circuit.  Here is a strange-looking flasher that uses an unusual form of the Marx high voltage multiplier.  The traditional Marx multiplier uses spark gaps to repetitively charge capacitors from a high voltage supply (in parallel) then to suddenly connect them in  series to generate a much higher voltage, near N times the supply voltage where N is the number of capacitors.  This multiplier uses Lumex gas tube transient suppressors (GT-RLSA3230D) as the spark gap, providing reliable and repeatable triggering at about 250 volts (much lower than the typical spark gap).  The 120 volt line voltage is rectified and doubled to provide enough voltage to trigger the suppressors and to reduce the required number of stages.   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

MD-4 8031 Microcontroller Motor driver kit -  The MD4 is a stepper motor driver design utilizing the 80C31 microcontroller.  The design is very similar to the MD-2 stepper motor driver board except that this board has an on-board +5V regulator so it does not require a dual voltage power supply to run.  It uses two Allegro UDN2540B ICs to driver the stepper motors.  The U1 is 8031AH microcontroller which can be replaced with any 80C32, 87C51, 87C52 or flash base microcontroller 89C51, 89C52 families.   __ Designed by www.wzmicro.com

Measurement and Control Circuit Collection -  Linear Technology AN45 __ Designed by Jim WilliamsJun 5th, 1991

Measures Capacitance or Inductance -  10/21/10 EDN-Design Ideas Use instruments you already have and a few equations when you don’t have a capacitance meter.   Design by Jim McLucas, Broomfield, CO

Mechanical_Underground_Gate_Opener -  Provide power to mechanical gates located opposite ends of a looping branch tunnel.  The gate was required to open and close perhaps only 2 times each month. The gates were set to open and then close again at ten minutes intervals.  Solution:  Use a wind generator.  . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 15 Jan 2011

Message Waiting Flasher -  This circuit starts flashing a neon light when the phone rings and continues flashing it until the phone is picked up to remind you to check your voice-mail.  The flashing neon light drives a voltage doubler (Q2) which keeps it flashing.  Q1 ensures that the __ Designed by Andrew R. Morris

Micro Based PIR to IR Remote Converter -  After the third attack on my car in 6 weeks, loosing 35 litres of fuel and generally having my day stuffed upI got really pissed off and embarked on the EKM-1 surveillance camera system.  Next time I want to get the act on video.  My first thought was to keep it simple and use a PIR (passive Infra-red) motion detector to set off an alarm in my bedroomthen I would manually start my VCR and record video from a low-light camera. __ Designed by Eddie Matejowsky

Micro Power Over-Temperature Alarm -  The circuit is powered for years by a single 3 volt lithium battery.  It sounds an alarm when the temperature exceeds a certain point.  With some minor changes the circuit could also be configured for an under temperature (freeze) alarm.  The circuit uses a. . . Circuit by David A. Johnson P.E.-June, 2000

Microcontroller Clapper Switch -  Introduction I always thought the clapper so cool.  For those who are lazy like me, turn on or off the bedroom light without getting out of bed, simple clap your hands is amazing.  Thinking about it I projected one for me.  Several __ Designed by Toddy Cangica

Microcontroller Controls Analog Phase Shifter -  06/12/08  EDN-Design Ideas By using a digital potentiometer in a phase-shift circuit, a microcontroller can precisely control phase shift Design by Nick Ierfino, IGS Technologies, Montreal, PQ, Canada

Microcontroller controls multichemistry battery charger -  09/28/00 EDN-Design Ideas Figure 1 is a generalized block diagram of a multichemistry battery charger.  A COP8ACC5 µC handles its key charging features.  The µC is available in a 20-pin(15 I/O pins] SOIC or a 28-pin(23 I/O pins] SOIC/DIP.  It contains 4 kbits of internal ROM.  The controller's A/D inputs monitor Design by Kelly Flaherty, National Semiconductor, Santa Clara, CA

Microcontroller converts digital-temperature-sensor readings without floating-point arithmetic -  03/05/09  EDN-Design Ideas Convert digital-temperature-sensor readings without floating-point arithmetic Design by Jordan Dimitrov, Toronto, ON, Canada

Microcontroller Interfaces to 24V -  11/18/10 EDN-Design Ideas Convert 24V industrial signals to TTL levels.  [Design Ideas by Adolfo Mondragon, Electrolux Products, Juarez, Mexico Design by Adolfo Mondragon, Electrolux Products, Juarez, Mexico

Microcontroller or DSP Controls On/Off Function -  13-Nov-03 EDN-Design Ideas In many applications, a single on/off button switches the power supply on or off.  Usually, the system switches off regardless of the processing function or workload the microcontroller or DSP circuit is currently handling.  The small circuit in Figure 1 is intended to make the microcontroller or DSP circuit the master over this on/off function Design by Dirk Gehrke, Texas Instruments, Freising, Germany, and Frans Ravn, ChemoMetec A/S, Alleroed, Denmark

Microcontroller Produces Analog Output -  16-Oct-03 EDN-Design Ideas A brushless dc motor needs several voltage levels to control its speed  0V to stop the motor, 5V to run it at maximum speed, and some voltages between these extremes to run it slower.  When you use such a motor in a system under microcontroller supervision, the microcontroller should generate all these voltages Design by Abel Raynus, Armatron International, Melrose, MA

Microcontroller takes control of comparator -  09/01/00 EDN-Design Ideas In many µC applications, a signal conditioner modifies an analog input signal from a sensor and passes it to the µC for processing.  The last stage of the signal conditioner is always a device that transforms the signal level to a value acceptable for the µC's input.  Usually, it is a comparator.  Often, this signal channel is open or closed for some programmable time period.   Design by Abel Raynus, Armatron International, Melrose, MA

Microcontroller visualizes hex code -  04/27/00 EDN-Design Ideas In µC systems, information exchanges usually use the hexadecimal 1-2-4-8 format; output data also appear in this format.  Reading the hex code is not a problem; several LEDs connected to the output lines can display the answer.  The problem arises when you wish to observe the output data.  Many engineers are unfamiliar with hex code and prefer to observe data in the common decimal format.   Design by Abel Raynus

Microcontroller Watches, Controls AC Power -  06/22/95 EDN-Design Ideas Circuit allows an isolated microcontroller to both sense and control ac power to an externally plugged-in deviceFor monitoring and controlling a power circuit from a microcontroller (µC), Fig 1 replaces the conventional technique of a low-value resistor and differential amplifier (with gain set for the expected current value).  A control line turns TRIAC Q1 on and off via optoisolator IC2.  When an appliance is plugged into J1 and turned on, the voltage drop across Q1 is independent of the current value and sufficient to turn on optoisolator IC3.  The phototransistor current of IC3 charges C1to a logic 1, which is sensed by the µC.   Design by Samuel Kerem, Infrared Fiber Systems, Silver Spring, MD

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

Micro-Power Flasher -  With this micro-power flasher you can baffle the intruders trying to break into your home.  The unit continuously emits flashing light both during day and night giving the impression that the...__ Electronics Projects for You

MicroPower Solar Engine -  A 'micro power solar engine' has been a goal since my introduction to BEAM Robotics.  I believe that if there wasn't one before, I there is one now.  What I'm presenting to you looks very similar to one of the circuits found in Steven Bolt's web pages.  As you will see, I made only minor changes to that design and not without help.   __ Designed by Ken Huntington

Micro-step driver-connect a bipolar steppe Motor to a PC through the parallel port -  This circuit allows to connect a bipolar step motor to a personal computer through the parallel port.  The circuit is, for safety reasons, optically isolated from the PC and it allows to manage motors up to 3A for phase.  Moreover, the digital interface allows to connect up to six motors to a single PC parallel port. __ Designed by © Vincenzo Villa

Microstepping stepper Motor driver with PBM3960 & TEA3718 -  This Microstepping motor driver offers a short cut to get familiar with microstepping.  It is a complete system to driver the bipolar stepper motor in micro-stepping mode as well as the half step and full step modes.  This board is built around the Ericsson PBM3960 (NJR NJU39610) microstepping controller and TEA3718 stepper motor driver __ Contact: info @ wzmicro.com

Miller solar engine -  The Miller solar engine uses a 1381* voltage detector (a.  k.  a.  , a voltage supervisor) IC to drive a voltage-based (type 1) solar engine.  The 1381 is normally used to reset CPUs and Micros when the power supply drops too low for reliable operation.  So 1381s detect and switch when the input voltage crosses the rated upper and lower threshold voltages.  The upper- and lower-switching voltages are slightly overlapped so that the turn-on voltage is a few hundred mV above the turn-off voltage.  This hysteresis keeps input noise (around the switching threshold) from resulting in multiple output cycles as the transition occurs.   __ Contact: Eric Seale

Mini Pocket Strobe -  This circuit is a mini storoscope which you can make so small that it can fit into your pocket.  The circuit is not very powerful, but is works out of two small 1.5V batteries for an hour constantly and maximum flash rate.  The flash rate is variable from zero to about 10 Hz.  Quite nice small device to have with you in parties to gain attention __ Designed by Tomi Engdahl

Miniature High-Rate Speed Control with BEC -  My first Speed 400 powered plane was the Sydney's Special, an 80% scaled down version of Vernon Williams' Fred's Special, as published in the November 1991 issue of Model Airplane News.  I chose this project because I was really happy with my original-size 46˝" Speed 600 powered Fred's Special.  The scaled down version has a 37" __ Designed by Stefan Vorkoettert

Miniature High-Rate Speed Control with Brake -  Many designs for high-rate speed controls have been published.  Most require two 8-pin integrated circuits   (ICs) or one 14-pin IC.  Many designs suitable for home construction are fairly large   (some as large as 2" square).  Many do not include a brake __ Designed by Stefan Vorketter

Miniature Real-Time Controller -  My long history homeuse controller, a Miniature Real-time Controller controls night light, A/C, household appliances with programmable scheduler.  Modified source code and hex file for year 2002 readout.  New source code in c program.   __ Designed by Wichit Sirichote

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