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Switch Circuits
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Last Updated: October 24, 2017 02:55 PM
Circuits Designed by Dave Johnson, P.E. :

Tap Switch uses a Piezo Wafer -  Two different switch circuits are shown.  One sources current and the second sinks current.  Both switches are connected to a piezo wafer.  When the wafer is tapped, the switches are activated . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Through Glass Push Button Switch -  This simple technique allows a mechanical pushbutton switch assembly to activate a reed type relay through a pane of thick glass.    Pushing the button moves a magnet near the reed relay, closing the relay contacts.   . . . Circuit by David A. Johnson P.E.-November, 2010

Touch Switch 240VAC -  This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Touch Switch controls a 120 VAC load -  This is a capacitance based touch on/touch off switch, which can control power to a 200 watt 120vac load . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Touch Switch Exciter -  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 . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Transistor-Switch Detects Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

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

Tap Switch uses a Piezo Wafer -  Two different switch circuits are shown.  One sources current and the second sinks current.  Both switches are connected to a piezo wafer.  When the wafer is tapped, the switches are activated . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Three-State Switch Interface Uses One Microcontroller Pin -  02/21/08  EDN Design Ideas:  A single microcontroller i/O pin senses the state of a three-position switch __ Circuit Design by Kartik Joshi, Netaji Subhas Institute of Technology, New Delhi, India

Through Glass Push Button Switch -  This simple technique allows a mechanical pushbutton switch assembly to activate a reed type relay through a pane of thick glass.    Pushing the button moves a magnet near the reed relay, closing the relay contacts.   . . . Circuit by David A. Johnson P.E.-November, 2010

Time Switch -  This circuit is especially designed for those who often need to wake up early in the morning.  Ordinary alarms in electronic watches are not loud enough and very often they fail to wake up.  The switch circuit described here will come handy; it can be used to switch on a TV, radio or tape recorder__ 

Time Switch V1.0 -  New weekly scheduler made by 68HC908QY4 with kaypad and 16x1 line LCD!  (not recommended)  __ Designed by Wichit Sirichote

Time-Controlled Switch using PIC16f72 -  APRiL 2012: A time-controlled switch is an automatic timer switch that turns an appliance on for the desired time duration.  After the preset time duration, the timer automatically switches off, disconnecting__ Electronics Projects for You

Toggle on off -  This circuit could be used to toggle on and off a NE555 output by a single momentary button.  Similar circuits are often used instead of  mechanical bistable relays, especially when the circuit must back to the start condition by switching off the power supply.   __ Designed by Andrea-Central Italy

Toggle Switch #1 -  This simple circuit will energize and de-energize a relay at the push of a button.  Any type of momentary action push-to-make switch can be used.  Pushing the button once - will energize the relay.  And pushing it a second time - will de-energize the relay __ Designed by Ron J.

Toggle Switch #2 -  Pushing the button once will energize the relay.  Pushing the same button a second time will de-energize the relay.  Any simple momentary action push-to-make switch will do.   __ Designed by Ron J.

Toggle Switch #3 -  This versatile circuit provides a selection of different switching modes.  it can be used as two entirely separate toggle switches - with each push button successively energizing and de-energizing its own relay.  Or the two switches can be interlinked with diodes - to produce a number of different switching patterns.  For example - the circuit can be used to reverse the direction of DC motors __ Designed by Ron J.

Toggle Switch Circuit -  This Toggle Switch uses the popular Johnson Decade counter IC CD4017.  By giving positive pulses to its clock input, the ten outputs of the IC becomes high one by one provided the reset pin is grounded.  By connecting the reset pin to any of the output, IC latches and the output remains high irrespective of__ 

Toggle Switch Debounced Pushbutton -  This is a unique and interesting circuit that I found somewhere.  it's a simple circuit that has two characteristics.  it debounces the pushbutton switch with just a few parts.  it also always comes up reset so that Q1 is on and Q2 is off.   __ Designed by John Lundgren

Toggles Illustrate Low Power-MOSFET Leakage -  7-Aug-08 EDN Design Ideas:  A novelty circuit demonstrates the low leakage of modern power MOSFETs __ Circuit Design by Tom Bruhns, Mukilteo, WA

Touch Activated Alarm -  Not much to tell here as the circuit speaks for itself.  The 555 can be almost any type, they are all pin-compatible.  Although some CMOS types may not have enough power to drive the transistor, in that case use an ordinary 555.  C1's working voltage should be increased to 25V if you decide to go with a 12V power source.  Change the value of C1 for the desired output pulse __ Designed by Tony van Roon  VA3AVR

Touch Keypad -  This board layout was created using the SOIC  version of a PIC 16F627A without drawing the usual schematic first.  Most of the part values are etched on the Layout.  The SiP resistor packs I used are 10k ohm, some experimentation with this value may be useful __ Designed by Luhan Monat-Mesa Arizona

Touch 'N Flip -  Ever wonder how a touch plate, like the kind you see on some elevators and lamps work?This circuit will give you a feel for how the touch plate works in a circuit and you can expand on the circuit to suit your project needs.  The touch plate.   __ Designed by Randy Linscott

Touch operated Band switch for Radio Set -  Touch switch are now in vogue for stereo decks and other audio and video sets.  This small circuit is meant for electronics enthusiasts to help them covert the manual bandswitch of their radio set to an electronics touch switch with band indicators using LEDs.__ 

Touch Operated Switch -  Touch operated switches are an attractive project for DiY electronics but they are not so common in commercial products.  The reason for this is that, although there are many different ways of implementing a touch switch (leakage, hum pickup, capacitance, albedo) all of them rely on body parameters which vary a lot with the person's body, age and environment so that a circuit which gives reliable operation with one development engineer may cause problems in use with, for instance, old folks living in arid areas.  Nevertheless touch switches can give excellent results.   __ Designed by Richard Torrens

Touch Sensative Relay Switch -  Our TOUCHER-TRS1 has many applications; Turn on for predetermine time light motor etc simply by touching sensitive metal pad.  Use the kit anywhere youd like to draw an audience and a smile show friend your magic-touch.  The unique small design will allow you to mount kit almost anywhere.  Operates from 9 to 12VDC (optional) , or via one of our 9 or 12 battery simulator/regulator kits.  The alternative uses are endless.  its designed for the beginner as well as the expert.   __ Contact Kit from Elich Industrial Development, Corp

Touch sensistive touchpad -  This board layout was created using the SOIC  version of a PIC 16F627A without drawing the usual schematic first.  Most of the part values are etched on the Layout.  The SiP resistor packs I used are 10k ohm, some experimentation with this value may be useful __ Designed by Luhan Monat-Mesa Arizona

Touch Sensitive Light Dimmer -  With IC SLB0586A from Siemens you can build a simple touch light dimmer circuit that will allow you to adjust the lamp intensity.  Together with a TIC 206D TRIAC, it enables smooth regulation of light intensity from a bulb of 10W 400W.  A coil of 100H/5A is required to suppress switching noise.  The voltage supply__ 

Touch Sensor Switch with 555 timer -  This is a very simple touch sensor switch that is build with the 555 timer IC .  You just need to touch the metal plate and the relay gets energised and is kept in this state for about 100 seconds, then is released.  This kind of sensor switch is suitable for making touch operated bells, buzzers of small toys which operate for a __ Designed by Popescu Marian

Touch Switch -  The Touch Switch circuit will detect stray voltages produced by mains voltages and electrostatic build-up in a room.  in the first circuit, pin 2 must see a LOW for the circuit to activate.  if sufficient static voltage is detected by the plate, the chip will change state.  if not, you will need to touch the plate and the 0v rail__ 555-Timer

Touch switch -  This circuit uses a 555 timer as the bases of the touch switch.  You can learn more about 555 timers in the Learning section on my site.  When the plate is touched the 555 timer is triggered and the output on pin 3 goes high turning on the LED and the buzzer for a certain period of time.   __ Designed by IQ Technologies

Touch Switch -  PIC  Project   __ Designed by Luhan Monat - Mesa Arizona

Touch Switch 240VAC -  This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Touch Switch controls a 120 VAC load -  This is a capacitance based touch on/touch off switch, which can control power to a 200 watt 120vac load . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Touch Switch Exciter -  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 . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Touch Switch II -  A touch switch is a switch that is turned on and off by touching a wire contact, instead of flicking a lever like a regular switch.  Touch switches have no mechanical parts to wear out, so they last a lot longer than regular switches.  Touch switches can be used in places where regular switches would not last, such as wet or very dusty areas. __ Contact IQ Technologies

Touch switch needs no DC return path -  3-Feb-05 EDN Design Ideas:  Common designs for touch switches detect a decrease in resistance when a user's fingertip either connects a contact to the circuit's common ground or supplies an injection of 60-Hz ac voltage, resulting from immersion in the electrostatic field that nearby power lines radiate.  But what if no nearby power lines exist and the equipment operates from a battery source, such as in an automotive appl __ Circuit Design by Brad Albing, Philips Medical Systems Inc, Cleveland, OH

Touch Switch using 4011 CMOS NAND Gate IC -  A touch switch is a switch that is turned on and off by touching a wire contact, instead of flicking a lever like a regular switch.  Touch switches have no mechanical parts to wear out, so they last a lot longer than regular switches.  Touch switches can be used in places where regular switches would not last, such as wet or very dusty areas __ Designed by Aaron Cake

Touch Switch using Transistors -  Schematic & notes only there no circuit description.   __ Designed by Tony van Roon  VA3AVR

Touch Switches -  One of the unusual features of the out-of-production Programmable Drum Set was its use of touch switches for control.  Like most touch switches, these detect the difference in the capacitance of a plate when it is being touched by a finger versus the parasitic capacitance of the plate alone. __ Designed by John Simonton

Touch Switchs -  Here is a great collection of touch switch circuits.  A touch switch is an electronic device that enables us to control a circuit by simply touching a sensor.  Simple touch switch circuit with 4011 source The circuit as you can see from its diagram is very simple and only uses 8 components.  The heart of the circuit is __ Designed by Popescu Marian

Touch Switchs -  All the circuits and projects we describe in these articles consist of very important "building blocks" that you can add to other designs.  This time we describe the concept of touching a plate (or two plates separated by a small gap) and turning a circuit ON or OFF.  A TOUCH PLATE is classified as a high impedance device __ Contact Collin Mitchell

Touch-Activated Timer Switch Extends Battery Life -  10-Jul-08 EDN Design Ideas:  Designed to fit into the battery compartment of an optical mouse, this circuit automatically shuts off the battery after a time delay __ Circuit Design by Israel Schleicher, Prescott Valley, AZ

Touch-Free Timer Switch -  This type of infrared proximity circuit is widely used as an electric switch where physical contact is not desired for hygiene purpose.  For example, we commonly see use of infrared proximity__ Electronics Projects for You

Transistor-Switch Detects Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

TRIAC Switch To Control High-Voltage Devices -  From ages electron-magnetic relays are being used as switches to control high voltage devices.  But, because of their bulky size and noise (both electrical and mechanical) people started using TRIAC with opto-coupler as better alternative.  Above circuit uses TRAIC  and Opto-coupler to use small voltage to control high voltage devices.  For example, micro-controller to control 220v bulb or any device which runs on high voltage. __ ` Sigmatone

Two buttons provide safe start -  07/06/00 EDN Design Ideas:  The circuit in Figure 1 provide as a safety interlock that checks the actuation of two pushbuttons before enabling a relay.  When you push both buttons, the circuit actuates the relay.  At that point, you can release one of the switches without the relay' __ Circuit Design by Vincent Himpe, Alcatel Microelectronics, Desselgem, Belgium

Two Light Controlled Relays -  Switching Circuits:  These two circuits use LDRs (Light Dependent Resistors).  Circuit No.1 energizes the relay when the light rises above a preset level. Use it to switch things on at dawn. Circuit No.2 energizes the relay when the light falls below a preset level. Use it to switch things on at dusk.  __ Designed by Ron J.

Two Line Intercom Plus a Telephone Changeover Switch -  The circuit presented here can be used for connecting two telephones in parallel and also as a 2-line intercom.  Usually a single telephone is connected to a telephone line.  if another telephone is required at some distance, a parallel line is taken for connecting the other telephone.  in this simple parallel line operation, the main problem is loss__ 

Two Temperature Controlled Relays -  Switching Circuits:  These two circuits use Thermistors (Temperature Dependent Resistors).  Circuit No.1 energizes the relay when the temperature rises above a preset level. Use it to switch things on when it gets hot. Circuit No.2 energizes the relay when the temperature falls below a preset level. Use it to switch things on when it gets cold.  __ Designed by Ron J.

Two wire 4 by 4 key keyboard interface saves power -  08/17/06 EDN Design Ideas:  Resistor matrix and microcontroller encode keypad - You can use a microcontroller that includes an ADC to design a two-wire-plus-ground keyboard interface.  For example, you can use a resistive voltage divider to identify a pressed key (Reference 1).  A microcontroller's integrated ADC typically presents an input resistance on the order of hundreds of kilohms, and, for adequate accuracy, its keypad divider should comprise relatively low-value resistors of 10s of kilohms.   __ Circuit Design by Stefano Salvatori, University of Rome, Rome, Italy, and Gabriele Di Nucci, EngSistemi, Rome, Italy

Two-button control for dangerous machines -  Two button control systems are used on dangerous industrial machines in order to protect the operators hands.  Just for hobby I made a circuit that turns on a relay by pressing two buttons simultaneously.   __ Designed by Andrea-Central Italy

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

 


Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches



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