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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E.

Model Airplane Wing Tip FlasherThe circuit below is designed to flash two white LEDs mounted at the wing tips of a model airplane.  The flasher unit is powered by a 4.5v supply made of three AA or AAA 1.5v alkaline battery cells.  The average current is about 2ma so a set of batteries . . . Hobby Circuit designed by David A. Johnson P.E.-October, 2009

Model Train Lighthouse Flasher RevisitedHO train sets often have authentic looking scale model homes and buildings.    A while back someone asked me to design a flashing LED light, which he could mount inside a model lighthouse and have it operate so it would appear to rotate and flash.    I designed a working circuit but I was never pleased with the results.    I’m still not 100% pleased but the revised circuit below seems to operate a bit better than the older circuit.  … [ . . . Hobby Circuit designed by Dave Johnson P.  E.  , May 2012] . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2012

Modified LED Night LightI bought some night lights a few months ago from Walmart here in Denver.  The devices were made by Elumina Lighting Technologies Inc.  (www.  eluminalighting.  com) , their model LED-6200A.  I think I paid about $15 for a pack of three lights.  I wanted a light . . . Hobby Circuit designed by David Johnson P.E.-May, 2007

Momentary Touch Activated SwitchA single 1.5v silver oxide button cell powers this complete touch activated switch circuit for 5 years.  It features both a normally open and a normally closed set of solid-state switch thermals.  It also has an adjustable sensitivity, which can be set for a touch capacitance change as small as 1 picofarad. . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2002

Monitor ON/OFF status of a Remote SwitchThere are many applications when a remote switch’s on/off status needs to be monitored.  Reed relay sensors, toggle control switches and security alarms contacts are just a few examples.  Routing a switch directly to a computer system hundreds of feet away . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2009




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

Miniature Stobe Light -  It is a circuit for a strobe light that uses a neon glow lamp with reflector to create an effect of a strobe light.  __ Electronics Projects for You

Minimize Noise In Power-Supply Measurements -  07/28/11  EDN-Design Ideas Eliminating excess noise from an oscilloscope probe yields better measurements.   Design by John Lo Giudice, STMicroelectronics, Schaumburg, IL

Minimize the Short-Circuit Current Pulse in a Hot-Swap Controller -  27-May-04 EDN-Design Ideas Because of internal circuit-breaker delay and limited MOS-gate pulldown current, many hot-swap controllers do not limit current during the first 10 to 50 µsec following a shorted output.  The result can be a brief flow of several hundred amperes.  A simple external circuit can counter this problem by minimizing the initial current spike and terminating the short circuit within 200 to 500 nsec Design by Jim Sherwin and Thong Huynh, Maxim Integrated Products, Sunnyvale, CA

Miser Flash -  A flashing LED at the doorstep of your garage or home will trick the thieves into believing that a sophisticated security gadget is installed.  The circuit is nothing but a low-current...__ Electronics Projects for You

MK5 Infra Red Repeater -  The latest addition to my collection of Infra Red (IR) Repeater circuits.  The Mark 5 is a much improved version of the Mark 1 circuit and has increased range and sensitivity.  It is also immune to the effects ofambient light, daylight and other forms of interference.  In addition it works with IR modulation freuencies in the range 30 to 120kHz making the Mk5 circuit the best choice for compatibility with remote controls __ Designed by Andy Collison

Model Aeroplane Navigation Strobe/Battery Level Indicator  -  If you are interested in model aeroplanes and have the capital, a radio controlled electric park flyer is a must have.  An RC aeroplane under 400 grams floats around like the rubber models of my youth and contact with the ground doesn't seems to involve that sickening crunch __ Contact: r dot p @ webone.com.au

Model Airplane Wing Tip Flasher -  The circuit below is designed to flash two white LEDs mounted at the wing tips of a model airplane.  The flasher unit is powered by a 4.5v supply made of three AA or AAA 1.5v alkaline battery cells.  The average current is about 2ma so a set of batteries . . . Hobby Circuit designed by David A. Johnson P.E.-October, 2009

Model Lighthouse -  This project was designed for a model lighthouse to flash a lamp or LED in a simple sequence: two flashes of 2s with a short gap of 1s, followed by a longer gap of 5s before repeating the sequence.  A 4017 counter is used to produce the flash sequence and this project includes information on how to adapt it to give a different flash sequence __ Designed by John Hewes

Model Railway Level Crossing Lights -  The level crossing warning lights are switched on automatically as a train approaches.  First an amber light shows, then two red lights flash until the train has passed the crossing.   __ Designed by John Hewes

Model Railway Signal -  This signal is controlled automatically by a passing train fitted with a magnet.  It can also be manually set to red or green by pressing the switches.  Trains will automatically stop at the red signal.   __ Designed by John Hewes

Model Train Lighthouse Flasher Revisited -  HO train sets often have authentic looking scale model homes and buildings.    A while back someone asked me to design a flashing LED light, which he could mount inside a model lighthouse and have it operate so it would appear to rotate and flash.    I designed a working circuit but I was never pleased with the results.    I’m still not 100% pleased but the revised circuit below seems to operate a bit better than the older circuit.  … [ . . . Hobby Circuit designed by Dave Johnson P.  E.  , May 2012] . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2012

Modeller’s Clock -  The special feature of this analogue wall clock is that it uses a standard model servo to tell the time.  The display principle is the same as for an ordinary wall clock, but with two important differences.  A standard model servo is unable to cover a travel of 360°, so we’ll need to adapt the clock face to this situation must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Modified LED Night Light -  I bought some night lights a few months ago from Walmart here in Denver.  The devices were made by Elumina Lighting Technologies Inc.  (www.  eluminalighting.  com) , their model LED-6200A.  I think I paid about $15 for a pack of three lights.  I wanted a light . . . Hobby Circuit designed by David Johnson P.E.-May, 2007

Modify Servo Motor for Continuous Movement -  Servo motors are widely used in precise control applications, but most of them can rotate up to 180 degrees only.  Presented here is a process for modifying servo motors so that...__ Electronics Projects for You

Modifying a Servo -  I was in need to modify four expensive JR-DS8231 Ultra Digital servos to rotate 360° instead of the standard 130° or something.  The mods were required so they could be used with a tethered blimp.  The infra-red and night vision camera equipment is mounted underneath the blimp on a special frabicated aluminum cage and is radio controlled (Tony van Roon's R/C)  __ Designed by Tony van Roon  VA3AVR

Modular Relay SystE - M -  This is simple transistorised relay into which can be plugged 'personality modules' to turn the base unit into a timer (pulse, delay on energise or delay on de-energise) or a latching relay or whatever is required.  This is therefore a universal relay system.  It was designed to simplify industrial machinery control.   __ Designed by Richard Torrens

Momentary switch controls mains with latch-on & remote shutdown -  12/30/13  EDN-Design Ideas Convert a momentary switch into one that latches as well as protects loads from rapid cyclingThe purpose of this Design Idea was to improve reliability, add new features, and replace a latching power switch with a momentary one Design by Peter Demchenko

Momentary Touch Activated Switch -  A single 1.5v silver oxide button cell powers this complete touch activated switch circuit for 5 years.  It features both a normally open and a normally closed set of solid-state switch thermals.  It also has an adjustable sensitivity, which can be set for a touch capacitance change as small as 1 picofarad. . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2002

Monitor ON/OFF status of a Remote Switch -  There are many applications when a remote switch’s on/off status needs to be monitored.  Reed relay sensors, toggle control switches and security alarms contacts are just a few examples.  Routing a switch directly to a computer system hundreds of feet away . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2009

Mono Hi-Fi Tone Control -  This is the mono tone control circuit.  The circuit will give you high fidelity (hi-fi) output.  Built the 2 similar circuit to make it stereo.  Use high quality electronic parts for better audio output quality. 

More stepping Motors -  There are so many ways to drive a stepper motor, Here is another circuit that use 74LS194 4 bit bi-directional universal shift register as a phase generator and UDN2543B to drive the unipolar stepper motor.  U1 74LS04 provide the necessary clock pulse for the circuit.  S1 is the direction selection switch and S2 turns ON/OFF the motor.   __ Designed by www.wzmicro.com

MOSFET switch provides efficient AC/DC conversion -  02/17/00 EDN-Design Ideas Occasionally, you have access to a transformer for powering a dc circuit, but its output voltage is much higher than that required for the dc voltage.  The full-wave-rectified and filtered output of an ac input voltage V X , is V DC =1.414V X-2V F , where V F is the forward drop in the rectifier (approximately 0.7V).    Design by Spehro Pephany, Trexon Inc, Toronto, ON, Canada

MOSFETs Reduce Crosstalk Effects On Analog Switches -  02/17/97 EDN-Design Ideas Some cost-effective analog multiplexer/demultiplexer ICs, such as the CD4053 and CD4066, find frequent use as signal distributors.  These digitally controlled analog switches have low on-resistance.  However, with all channels in the same package, crosstalk can be annoying and unavoidable.  Figure 1 provIdeas a cost-effective and viable method of solving this problem.  By simply adding some n-channel MOSFETs, such as the 2N7002 or 2N7000, the crosstalk effect becomes negligible.  When the Channel Select signal is high, the CD4053's input pins A, B, and C assume a level of nearly 0V.   Design by Stanley Chen, Global Mixed-Mode Technology, Taipei, Taiwan

Motion Controlled Blinking Eyes -  13-May-14 -Design News:   This is Mark II of my Animatronic Eyes, which was created for someone who wanted to animate a rock sculpture.  The eyes themselves were made with plastic Easter egg tops, which fit perfectly as eyelids over ping pong balls.  The problem there becomes one of mounting and alignment.  In this version, __ Gadget Freak-Case #254

Motor Control through PWM -  Motion control plays a vital role in industrial automation.  It is required in manufacturing plants of industries like chemical, pharmaceutical, plastic and textile.  And it may be a flat-belt application, flow-control...__ Electronics Projects for You

Motor controller operates without tachometer feedback -  12/09/99  EDN-Design Ideas Speed controllers have long exploited the reverse-EMF characteristics of dc motors to control their speed.  These linear driver circuits use power op amps to create a negative resistance drive to the motor that counteracts the voltage drop in the motor's Design by Bruce Trump

Motor Protection/Regulation -  The LTC2991 is used to monitor system temperatures, voltages and currents.  Through the I2C serial interface, the eight monitors can individually measure supply voltages and can be paired for differential measurements of current sense resistors or temperature sensing transistors.  Additional measurements include internal temperature __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Motor PWM -  The speed of a motor can be adjusted by this circuit, from 5% to 95%.  __ 555-Timer

Motor Speed Control -  This circuit will allow you to control the speed of an AC motor, for example an electric drill.  The way that this circuit works is as follows.  The bridge rectifier produces dc voltage from the 120vac line.  A portion on this current passes through the 10K ohm pot.  The circuit comprised of the 10k pot, the two 100 ohm resistors and the 50uf capacitors delivers gate drive of the SCR.  The diode D1 protects the circuit from reverse voltage spikes.  The ratings of the bridge rectifier and the SCR should be 25 amps and PIV 600 volts.  The diode D1 should be rated for 2 amps with PIV of 600 volts.  The

Motor Speed Regulator -  This circuit regulates the speed of a small drill motor I use for PC board work.  It is much handier for delicate work than a larger AC powered tool.  The tool I have came with a useless 9 volt AC adapter.  The motor would whine at high RPMs unloaded, but wo __ Designed by Andrew R. Morris

Motor-controller uses fleapower -  09/25/03  EDN-Design Ideas A simple, permanent-magnet dc motor is an essential element in a variety of products, such as toys, servo mechanisms, valve actuators, robots, and automotive electronics.  In many of these applications, the motor must rotate in a gi Design by Anthony Smith, Scitech, Biddenham, Bedfordshire, UK

Motorcycle Brake Light Flasher -  Several years ago one car manufacturer added a rapid flasher to their brake lights.  Wow! Those things really got your attention when the driver stepped on the brakes.  But, if you ever had to stop behind one at a traffic light at night, you were likely to go into seizures from the strobing, rear lights covering your field of vision.  I think they dumped the idea __ Designed by Tony van Roon  VA3AVR

Motorcycle Low Voltage Warning -  This circuit is connected to your motorcycle.  It's tapped into a circuit thats only powered with the key "ON".  If you turn the bike off with the kill-switch and leave the key on, as you know, the headlight will stay on and quickly drain the battery.   __ Designed by Tony van Roon  VA3AVR

Motorcycle Turn-signal SystE - M -  This circuit is based on the CMOS IC from Motorola, the MC14049UB Hex Inverting Buffer.  Of course, the regular CD4049 can be used and is pin-for-pin compatible.  The 4049 is a 16-pin chip.  Maximum DC supply voltage should not exceed 18V.  The above diagram can replace your existing mechanical clicker.  The prototype worked excellently! __ Designed by Tony van Roon  VA3AVR

Motorized Video Camera Mount -  This article describes a motorized, waterproof mount for a miniature video camera.  If a suitable waterproof camera is used, this unit can be used outdoors.   __ Designed by G. Forrest Cook

MP-3 Stereo Transmitter with USB control from a PC -  This low cost MP-3 player was designed to be run from a PC via a USB interface.  The MP-3 audio from a PC sound card is transmitted to a home stereo via a synthesized FM Transmitter.  Also included is a 433 MHz wireless remote control to provide basic VCR type functionality to the whole design.   __ Designed by Steve Hageman

Multidisplay LED Controller -  LTC3205__ Linear Technology/Analog Devices

Multi-Function Remote-Controlled Lamp Dimmer -  You probably think that a dimmer is a dimmer is a dimmer, right? This little beauty will definitely change your mind!__ SiliconChip

Multiutility Flash Light -  This multiutility flash light consists of three sections: a flasher, a sound-to-light display and a white LED-based flashlight.The flasher circuit (Fig.1) is built around an NE555 timer IC that is...__ Electronics Projects for You

Musical Instrument (Expandable) Graphic Equaliser -  This equaliser is designed as a preamp suitable for musical instrumentsguitar, bass and keyboard in particular.  Unlike most conventional graphic equalisers, each slider ranges from fully off to fully on, and not the more conventional +/-12dB or so that is normally available.   __ Designed by Rod Elliott  ESP

Mute for Big Briar Etherwave® Theremin -  This circuit permits the addition of a "mute" switch to the Etherwave® Theremin, useful for placing the theremin in a silent mode without having to turn it off completely.  There is no "pop" during the mute-unmute transition.  A MUTE STATUS light-emitting diode doubles as a convenient power indicator.  The circuit was constructed on a small circuit board installed inside the theremin.  The MUTE CONTROL switch  __ Designed by Arthur Harrison

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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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