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Last Updated: November 22, 2021 02:41 PM
Circuits Designed by Dave Johnson, P.E. :

Hidden Panic Switch  -  Design an electronic switch which would be positioned behind a wall at several key positions and would be activated when an adult human hand was pressed against the wall at that position.  The best way to detect the human hand against a wall was with a capacitance switch.  The QTFS3X from Faraday switches looked like a perfect match.  The switch could be powered by a DC voltage down to 3v.  It required only 30ua of current.  It was quite small and would easily fit behind the wall. . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 18 May 2011

High Power Touch Switch Exciter Circuit -  if you have hundreds of touch switches that need an excitation signal, then this circuit is what you need.  its 20KHz 20v peak to peak output signal can supply up to 3 watts of touch switch excitation power . . . Circuit by David A. Johnson P.E.-February, 2002

Infrared Reflected Light Switch -  Drawing only 30uA from a 3v supply, this circuit will detect a human finger with a range of about 1 inch.  The sensor uses an inexpensive infrared LED and a matching photo diode . . . Circuit by David A. Johnson P.E.-July, 2006

Infrared Safety Switch -  Using a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch . . . Circuit by David Johnson P.E.-July, 2006

Isolated Remote Switch Circuit -  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 . . . Circuit by David Johnson P.E.-January, 2009

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407




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

Hard Disk Switch -  in these times with viruses and other threats from the internet it would be nice to have reassurance that the PC cannot be infected.  That is why this circuit was designed.  it makes it possible to install multiple hard disks inside the case of a PC, which are separated in such a way that viruses__ 

Hdd Selector Switch -  Using the switch-mode power supply (SMPS) of your personal computer, this add-on circuit lets you switch between three hard disk drives (HDDs) and also ensure that nobody else can open your__ Electronics Projects for You

Heat Sensitive Switch -  At the heart of this heat-sensitive switch is IC LM35 (IC 1) , which is a linear temperature sensor and linear temperature-to-voltage converter circuit.  The converter provides accurately linear and directly proportional output signal in millivolts over the temperature range of 0°C to 155°C.  it develops an output voltage of 10 mV per degree centigrade change in__ 

Heat-Sensitive Switch -  At the heart of this heat-sensitive switch is IC LM35 (IC 1) , which is a linear temperature sensor and linear temperature-to-voltage converter circuit.  The converter provides accurately linear and directly proportional output signal__ Electronics Projects for You

HeNe Laser Transmitter/Receiver -  This set of two circuits from the basis for a very simple light wave transmitter.  A LASER beam is modulated and then aimed at a receiver that demodulates the signal and then presents the information (voice, data, etc).  The whole thing is very easy to build and requires no specialized parts execpt for the LASER itself.  LASERs are available from MWK industries.   __ Designed by Aaron Cake

Hidden Panic Switch  -  Design an electronic switch which would be positioned behind a wall at several key positions and would be activated when an adult human hand was pressed against the wall at that position.  The best way to detect the human hand against a wall was with a capacitance switch.  The QTFS3X from Faraday switches looked like a perfect match.  The switch could be powered by a DC voltage down to 3v.  It required only 30ua of current.  It was quite small and would easily fit behind the wall. . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 18 May 2011

High Current MOSFET  Flip Flop with Debounced Pushbutton -  This circuit was adapted from the "Toggle Switch Debounced Pushbutton" by John Lundgren.  it is useful where the load needs to be switched on from one location and switched off from another.  Any number of momentary (N/O) switches or push buttons can be connected in parallel.  The combination (10K, 10uF and diode) on the left side of the schematic insures the circuit powers up with the load turned off and the NPN transistor conducting.  These components can be omitted if the initial power-on condition is not an issue. __ Designed by Bill Bowden

High Efficiency Linear & Switching Solutions for Splitting a Digital Supply -  DN172 Design Notes __ Linear Technology/Analog Devices

High Power Touch Switch Exciter Circuit -  if you have hundreds of touch switches that need an excitation signal, then this circuit is what you need.  its 20KHz 20v peak to peak output signal can supply up to 3 watts of touch switch excitation power . . . Circuit by David A. Johnson P.E.-February, 2002

High-side current-sensing switched-mode regulator provides constant-current LED drive -  04/14/05 EDN Design Ideas:  Many suitable circuits exist for driving LEDs in constant-current mode and from low-voltage sources. For example, references 1, 2, and 3 show circuits that use switched-mode-regulator ICs  and low-voltage sources to supply LED current. Design by Bradley Albing, Philips Medical Systems Inc, Cleveland, OH

Hit Switch -  This versatile hit switch is the electronic equivalent of a conventional switch.  it can be used to control the switching of a variety of electronic devices. The circuit of the hit switch__ Electronics Projects for You

Home-made light-operated camera trigger -  it is more expensive (around $150 for parts instead of $30) , but is easier to construct, and vastly more flexible since it is based on a programmable microcontroller that can have new functions downloaded from a computer instead of having to build with more hardware.   __ Designed by © Mark Harris 2010

Hot-Swap Switch Provides Easy Thermal Protection -  9-Jul-09 EDN Design Ideas:  Remove power from your circuit when things get too hot Design by Donald Schelle, National Semiconductor Corp, Santa Clara, CA

Improve efficiency of low-cost switcher -  EDN Design Ideas:  07/21/2014     Reduce losses by over 30%, and improve Vin (min) too, on a 34063-based or similar switcher Design by Peter Demchenko

Improve On Low-Cost Keyboard -  10/30/03  EDN Design Ideas:  You can easily improve on a previous Design ideas - to produce a slightly simpler resistor arrangement with better timing balance between switches, using a single resistor value (Reference 1, Figure 1].  The use of a single resistor val Design by Martin O'Hara, Telematica Systems Ltd, Cranfield, Bedfordshire, UK

Impulse Changeover Switch -  So what on earth is an 'impulse changeover switch'? Easy - a switch which changes state each time it gets an impulse.  You may think it's just a fancy name for a bistable - OK I admit it.  However in the welding industry we used to use an 'impulse changeover relay' to control the direction of a d.  c.  motor used to oscillate a welding head between mechanical end stops.  There was a roller-lever operated microswitch and two adjustable position blocks.  Each time the microswitch hit a block, the relay changed over.  How crude can you get?  __ Designed by Richard Torrens

Inexpensive Power Switch Includes Submicrosecond Breaker -  3-Dec-09 EDN Design Ideas:  Control power to a load and protect the power source Design by Anthony H Smith, Scitech, Bedfordshire, England

Infra Red Switch -  acsiI Drawing __ Contact IQ Technologies

Infra Red Switch -  This is a single channel (on / off) universal switch that may be used with any infra Red remote control using 36-38kHz. (This is a very common remote handset frequency).  in place of iR1 a TSOP1738 receiver may be used.     __ Designed by Andy Collison

Infrared Reflected Light Switch -  Drawing only 30uA from a 3v supply, this circuit will detect a human finger with a range of about 1 inch.  The sensor uses an inexpensive infrared LED and a matching photo diode . . . Circuit by David A. Johnson P.E.-July, 2006

Infrared Safety Switch -  Using a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch . . . Circuit by David Johnson P.E.-July, 2006

Infra-Red Switch -  The component values must be chosen to give a frequency of oscillation to suit the receiver module to be used.  in most cases this will be 40kHz but you should verify this before starting construction.  The resistance in series with the diodes should be about 22W (its value is not critical)  __ Designed by © David Hoult

Infrared Switch Is Controlled By A TV Remote. -  Nowadays Appliances used to control almost any function with remote control.  But can not put the remote to control other electrical appliances.  We can do this project With the following – Can be used with almost any infrared remote.  – Can choose to work, or SPST switch or normally open pushbutton switch.  -There are output__ 

Infrared Toggle Switch -  This infrared toggle switch can be controlled by any TV/VCR remote operating at 38kHz frequency.  The circuit uses readily available, low-cost components and can be assembled on a small veroboard.Fig.1__ Electronics Projects for You

Infrared Transmitter & Receiver Schematic Diagrams -  Schematic only, there is no circuit description given__ 

Inline equations offer hysteresis switch in PSpice -  08/16/01 EDN Design Ideas:  Smooth-transition switches are convenient devices in many Spice-based simulators.  Their action can greatly ease the convergence process.  Unfortunately, these devices lack inherent hysteresis, a heLPFul feature used to build UVLO (undervoltage-lockout] systems, oscillators, and other systems.  intusoft's (www Design by Christophe Basso, On Semiconductor, Toulouse, France

Intelligent Switch -  This intelligent switch circuit enables automatic, switching on of an emergency light system during darkness in the event of mains failure.  The mains power failure condition is detected by the section__ Electronics Projects for You

Intelligent Video Switcher -  Monitoring several cameras on one monitor is usually done in one of two ways:  divide the screen into sections and show them all at once, or time sequence the cameras onto the whole screen.   __ Designed by Luhan Monat-Mesa Arizona

Interrupt-driven keyboard for MCS-51 uses few components -  26-May-05 EDN Design Ideas:  interface keypad easily to a microcontroller i/O port Design by Sandeep M Satav, Indian Institute of Technology, Bombay, India

Introduction, Definition of terms, Q&As-sw13-2 -  Application Note__ MiniCircuits.com

IR Receiver Toggle Switch -  The IR receiver circuit featured here is basically a simple  toggle switch that responds to IR signals from common hand  held remote controls.  it provides a means of controlling power  to electrical appliances not equipped for remote operation, without needing an additional controller. __ Designed by Bill Bowden

IR remote switch -  imagine the convenience of selecting TV channels using your remote and then pointing the same remote to your switchboard to switch on/off the fan or the tube light.  Here is a__ Electronics Projects for You

IR Terminal, Remote -  This unit provide 2 way IR communications using a numeric keypad and an LCD display.  Data is sent and recieved in acsiI with no regard to what the data means to any particular device __ Designed by Luhan Monat-Mesa Arizona

Isolated Remote Switch Circuit -  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 . . . Circuit by David Johnson P.E.-January, 2009

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Got Designs?
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if you want me to link to and/or post your original design Thanks.


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