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Last Updated: January 01, 2018 04:02 AM
Circuits Designed by Dave Johnson, P.E. :

AC to DC (240v to 5v)Power Supply -  This is simple way to power some 5v logic from a 240vac source.  if a 120vac power adapter is used, the circuit will also work for 120vac power lines . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

AC/DC relay from Charge Coupled MOSFET -  This circuit acts as an AC/DC relay with a rating up to 50 volts peak and up to 10 amps of current.  The differential oscillator supplies voltage to the gates of the two FETs with good isolation will drawing only 1.5ma of current . . . Hobby Circuit designed by David Johnson P.E.-October, 2005

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747




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

A 4-Digit Alarm Control Keypad -  Alarm Control Keypads:  This Keypad is suitable for the Modular Burglar Alarm.  However, it has other applications.  Pressing a single key will energize the relay.  Entering the Four-Digit code of your choice will de-energize it.  __ Designed by Ron J.

A 5-Digit Alarm Control Keypad -  Alarm Control Keypads:  This Keypad is suitable for the Modular Burglar Alarm.  However, it has other applications.  Entering the First Four Digits of your chosen Five-Digit code - will energize the relay.  Entering the Full Five-Digit code - will de-energize it. __ Designed by Ron J.

A home-made light-operated camera trigger -  This device is used to photograph moving objects by triggering a camera or flashgun when one or two light beams are interrupted.  it was designed to capture insects in flight, but can also be used for projectiles and anything else that moves too fast or irregularly to be photographed by hand.  it cost around $30 to build, and was used to make The Barista Collection. __ Designed by © Mark Harris 2010

A Low Battery Cutoff -  Also acts as a Master On / Off Switch.  NOW, Also a New P-Mos Version.  Supplies Positive voltage to grounded devices.   __ Designed by G.L. Chemelec

A Low Cost AT Keyboard Translator -  This Low-cost project takes the complex scan codes from a PC keyboard and spits out standard ACCiI codes.  it's just the shot for use with the BASIC  stamp and PIC  series of microcontrollers but has lots of other uses as well.__ SiliconChip

A Simple Circuit home-made light-operated camera trigger -  This device is used to photograph moving objects by triggering a camera or flashgun when one or two light beams are interrupted.  it was designed to capture insects in flight, but can also be used for projectiles and anything else that moves too fast or irregularly to be photographed by hand.  it cost around $30 to build, and was used to make The Barista Collection. __ Designed by Mark Harris Photography

A Simple Circuit Light Control Switch -  This is a simple LM311 Comparator based switch which can be used for various purposes: __ Designed by Nina Gajjar

AC Mains Bistable Switch -  This AC mains-operated bistable switch turns on or turns off a device using a miniature neon lamp and a few discrete components.  This switch can be used for control panels, appliances__ Electronics Projects for You

AC Power Line Power Load Sensing Automatic Switch -  WARNiNG:  This circuit requires experience with mains wiring.  Do not attempt construction unless experienced and capable.  Death or serious injury may result from incorrect wiring.   __ Designed by Rod Elliott  ESP

AC Power Line Slave Switcher -  There are many situations where two or more pieces of equipment are used together and to avoid having to switch each item on separately or risk the possibility of leaving one of them on when switching the rest off, a slave switch is often used.  __ 

AC Switch -  An AC triggered switch for low frequency signals.   __ Designed by Andy Collison

AC Switch Control with Opto-Triac -  AC switches are silicon devices that control AC loads directly connected to the AC mains.  This means that the driving reference terminal of the AC switch can be connected to the__ Electronics Projects for You

AC to DC (240v to 5v)Power Supply -  This is simple way to power some 5v logic from a 240vac source.  if a 120vac power adapter is used, the circuit will also work for 120vac power lines . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

AC/DC relay from Charge Coupled MOSFET -  This circuit acts as an AC/DC relay with a rating up to 50 volts peak and up to 10 amps of current.  The differential oscillator supplies voltage to the gates of the two FETs with good isolation will drawing only 1.5ma of current . . . Hobby Circuit designed by David Johnson P.E.-October, 2005

Accurate Foot-Switch -  Certain industrial controls require accurate switching operations.  For example, in case of a foot-switch for precise drilling work, even a small error in switching may cause considerable loss.  This low-cost but__ Electronics Projects for You

Add a grounded-switch feature for Top Switch on/off control -  06/21/07  EDN Design Ideas:  Adding a couple of components to the control pin of a Topswitch switching regulator enables on/off control __ Circuit Design by Robert N Buono, Aeolian Audio LLC, Bloomfield, NJ

Add voice command to virtual instrumentation -  05/30/02 EDN Design Ideas:  Debates still persist in the engineering community about the relative merits of analog and digital controls of instrumentation.  Meanwhile, a revolutionary new type of control—voice-command control—is gaining acceptance in many application areas (Reference 1].  This design idea focuses on the practical implementation of the Voice Commander voice-command interface in a virtual-instrume __ Circuit Design by Alexander Bell, Infosoft International Inc, Rego Park, NY

Add voice commands to your CAD system -  05/02/02 EDN Design Ideas:  The first time I activated the Language Bar (Speech Tools] in my Microsoft Word 2002 and started dictating this Design idea, the on-screen title displayed "cat" instead of "CAD.   " By using the "Add/Delete Words" feature, I'vetrained the system to recognize the "CAD" acronym.  This was my first experience with the MOSR (Microsoft Office Speech Recognition] tool, which is part of the latest Micros __ Circuit Design by Alexander Bell, Infosoft International, Rego Park, NY

Adjust Power-Efficient LED Switch to Any Light Intensity -  EDN Design Ideas:  06/20/12    Drawing only microamps (other than load current) , this circuit switches in accordance with ambient light levels. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, India

Alarm control keypad -  The IC is a quad 2 input "AND" gate, a CMOS 4081.  These gates only produce a HiGH output, when BOTH the inputs are HiGH.  When the key wired to 'E' is pressed, current through R1 and D1 switchs Q5 on.  The relay energises; and Q5 is 'latched on' by R8.  Thus, the Alarm is set by pressing a single key, say one of the two non-numeric symbols __ Designed by Ron J.

Algorithm tests for point location -  08/03/00 EDN Design Ideas:  A recent software project approximated the phase-space trajectory (also known as a strange attractor) of a certain dynamic system by using several nonoverlapping triangles.  it became necessary to determine whether particular opera __ Circuit Design by Lawrence Arendt, Manitoba HVDC Research Centre, Winnipeg, Canada

Alternating On-Off Switch, #1 -  This circuit uses three easily available 555 timer IC s.  All three work as astable multivibrators.  The first 555 has an on period and off period equal to 1 sec.  This IC controlson/ off periods ofor 2 555s which are used to flash two bulbs throughrelay contacts __ Designed by Tony van Roon  VA3AVR

Alternating On-Off Switch, #2 -  This circuit is the transistor version of the 4069 CMOS type.  Every press of the push-button will activate or de-activate the relay.  if you decide to mofify the circuit for 9V or higher, make sure the working voltage of the electrolytic capacitors are 25V instead of 16V.  The BC557B and BC337-40 are European transistors manufactured by Philips in the Netherlands.  Replacements such as the 2N3406 (PNP) , 2N3904 (NPN) , are okay, just watch the pin orientation which differs in regards to the collector/emitter __ Designed by Tony van Roon  VA3AVR

AN122 - Diode Turn-On Time Induced Failures in Switching Regulators -  Linear Technology AN122 __ Designed by Jim Williams - Jan 16th, 2009

AN-80-004  Using the RSW-2-25P switch -  AN-80-004 Application Note__ MiniCircuits.com

Analog switch acts as DC/DC converter -  01/20/00 EDN Design Ideas:  Many low-current devices that require 65V supplies can operate reliably in a single 5V power-supply environment if you use an appropriate localized DC/DC converter to generate  -5V bias.  Often,   capabilities and advantages of se 5V ICs  far outweigh  minor inconvenience and added costs of an additional -5V-converter function.  Many __ Circuit Design by John P Skurla, Advanced Linear Devices Inc, Sunnyvale, CA

Analog switch converts 555 timer into pulse-width Modulator -  15-Feb-07 EDN Design Ideas:  Added CMOS switch enhances a PWM oscillator __ Circuit Design by Jordan Dimitrov, Tradeport Electronics, Vaughan, ON, Canada

Analog Switch Cuts Peak-Detector Reset Time -  05/25/95 EDN Design Ideas:  The schematic in Fig 1  is a basic configuration for a unity-gain peak detector using the PKD-01FP monolithic peak detector from Analog Devices.  The reset time, tRES, is the time necessary to discharge the hold capacitor CH.  tRES  and the acquisition time tACQ are functions of the IC 's output-current capability.  With CH10 nF, this output-current limitation sets both tRES and tACQ to about 220 �sec __ Circuit Design by Gualtiero Bolognesi, Landis & Gyr, Peschiera Borronmeo, Italy

Analog switch expands I2C interface -  11/22/01 EDN Design Ideas:  Perhaps the most effective way to gain board space and increase component density is to minimize wiring on the board.  A widely used architecture that allows such miniaturization is the i2C bus.  Comprising only a bidirectional data line, SDA, and a clock line, SCL, this bus requires no chip selects or other additional connections __ Circuit Design by Luca Vassalli, Maxim Integrated Products, Sunnyvale, CA

Analog switch frees stuck I˛C bus -  26-Jun-03 EDN Design Ideas:  The dual-channel PCA9540 i2C multiplexer often breaks up an i2C or SM bus or allows you to use devices with the same addresses on the same bus.  When the PCA9540 initially powers up, it comes up in a state in which both channels are deselected.  The i2 C- or SM-bus master can then address the control register in the PCA9540 to select either Channel 0 or Channel 1, connecting the master to the ap __ Circuit Design by Bobarshall, Philips Semiconductor, Morgan Hill, CA

Analog switch lowers relay power consumption -  20-Dec-01 EDN Design Ideas:  Designers often use relays as electrically controlled switches.  Unlike transistors, their switch contacts are electrically isolated from the control input.  However, the power dissipation in a relay coil may render the device unattractive in battery-powered applications.  You can lower this dissipation by adding an analog switch that allows the relay to operate at a lower voltage (Figure 1)  __ Circuit Design by Steve Caldwell, Maxim Integrated Products, Chandler, AZ

Analog switch lowers relay power consumption -  Abstract: Design idea   outlining a method to use an analog switch and discrete components to reduce the power dissipated in relay actuation -- Relays are often used as electrically controlled switches.  Unlike transistors, their switch contacts are electric__ Maxim Integrated APPLICATION NOTE 956

Antenna extension provides open-door policy -  02/16/98 EDN Design Ideas:  Metal garage doors may be solid and secure, but they are not transparent to radio waves.  if your garage has aluminum siding, you may experience frustration with the operation of your garage-door opener.  if you must drive.   File contains many circuits, please scroll to find this one __ Circuit Design by Richard Panosh, Vista, Bolingbrook, IL

Anticipating timer switches before you push the button -  3-Apr-03 EDN Design Ideas:  Virtual-zener circuit simplifies high-voltage interface - (Editor's note This Twilight Zone-worthy circuit will be the subject of an upcoming network sitcom, My Big Fat Anticipating Timer.   ] it happens to almost everyone that an apparatus or system should have been turned off a moment ago.  The device in question could be the car heater, the air conditioner, the lights __ Circuit Design by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland

Appliance Timer-Cum-Clap Switch -  PANKAJ D.  CHOUDHURY When planning for a week-end outing to return late in the evening, we are often in an ambivalence whether to leave the staircase/outside light ‘on’ or ‘off.’ We sometimes__ Electronics Projects for You

AT89C2051/4051 Scanning 7 Segment Display & Keypad -  Since the output buffer ofP1 can sink 20mA (each output pin, but maximum iOL for all outputs was limited at 80mA) , thus we can use P1 to drive LED display directly.  As shown in the circuit, Two common-anode 7-segment LEDs are connected to P1 with 180 Ohms current limiting resistor.  Each segment of two LED __ Designed by Wichit Sirichote

ATX Power Switch Substitute -  An additional push-button switch is normally required for the ATX Power Switch/Soft Power Switch signal, but you can do without it if you use this simple circuit.  it is an artful design, but it has been repeatedly tested.  The zener diode is intended to provide protection against excessive voltages and reverse-polarity connection.  in the latter__ 

Audio/ Video Switch (8 x 8) -  This is an 8-input x-output audio/video switch module to be controlled from a computer, for example fromparallel port.  Each audio/video output can be switched to any of8 inputs, separately.1-module drives1-audio/video output and has a34-pin connector to plug intosystem interface.  You can use video OPA-s on 4051 output instead.  Note that you can get full integrated video multiplexers from Maxim __ Designed by Peter Jakab

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


Switches:  #'s - C       D - L       M - Q       R - S       T - Z


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


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