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Sensors / Detectors: Capacitance / Touch Switch Circuits
Sensors / Detectors Main Page

Capacitance Switches:   #'s - O       P - Z

Last Updated: June 04, 2021 06:51 AM

Circuits Designed by Dave Johnson, P.E. :

Pushbutton Switch works through Glass 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 Johnson P.E.-February, 2002

Solid State Touch Activated Switch It does not get any easier if you want a solid state switch that is activated by the touch of a finger.  Two small metal pins route voltage through the finger skin to a MOSFET switch.  The circuit is great for situations where a membrane type mechanical switch . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

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 Activated Switch This circuit provides about one watt of non-isolated DC power for an automotive type 12v LED array lamp in addition to a standard incandescent table lamp.. . . Circuit by Dave Johnson P.E.-January, 2002

Touch Activated Battery Powered Latching Relay -  A client needed a touch activated switch.  The unit needed to be fairly small and wired into the underside of some kitchen cabinets.  When touched, a string of fluorescent or LED lights, mounted under the cabinets, would turn on.  The total light power is less than 100 watts.  The system into two parts.  (1) A relay is mounted inside a plastic junction box and (2) a touch switch module.    Four wires leading from plastic junction box would connect to a second box containing the touch switch module.  The circuit is a simple relay driver powered by a9v battery. . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 20 Nov 2011

Touch Alarm for Door Knob I designed this hobby circuit many years ago and it seems be a very popular construction project.  Many companies offer simple alarm devices for personal use in bedrooms or hotel rooms.  A metal chain attached to a box holding the electronics is place . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2000

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 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

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

Pushbutton Switch works through Glass 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 Johnson P.E.-February, 2002

Reflected Infrared Light Switch Infrared light reflected off a finger is used to activate this switch circuit.  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 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Simple  Touch-Sensitive Switch This touch-sensitive switch is built around NAND gate IC CD4011 and transistor BC547.  When someone touches plate 1 (which is connected between pin 1 of gate N1 and ground), the RS flip-flop...___ Electronics Projects for You

Simple Circuit Touch Alarm Touch the sensor of the alarm with your finger and it starts beeping, goes on for some time and then stops.  Touching it again, and it goes again! This little and flexible circuit consists of a touch sensor and a directly coupled transistor amplifier with a small loudspeaker as the output load.  Two sensor strips of metal are __ Designed by T.K. Hareendran

Single Output 120VAC 200 Watt Touch Switch This simple circuit uses a single IC to form a nice touch switch circuit.    A single transistor forms the remote active switch sensor.    Multiple switches can be wired in parallel.    The switch circuit can be located about 500 feet from the control circuit. . . . Hobby Circuit designed by David Johnson P.E.-February, 2010

Solid State Touch Activated Switch It does not get any easier if you want a solid state switch that is activated by the touch of a finger.  Two small metal pins route voltage through the finger skin to a MOSFET switch.  The circuit is great for situations where a membrane type mechanical switch . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

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 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 Activated Lamp The circuits below light a 20 watt lamp when the contacts are touched and the skin resistance is about 2 Megs or less.  The circuit on the left uses a power MOSFET which turns on when the voltage between the source and gate is around 6 volts.  The gate of the MOSFET draws no current so the voltage __ Designed by Bill Bowden

Touch activated switch 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 Activated Switch This circuit provides about one watt of non-isolated DC power for an automotive type 12v LED array lamp in addition to a standard incandescent table lamp.. . . Circuit by Dave Johnson P.E.-January, 2002

Touch Activated Battery Powered Latching Relay -  A client needed a touch activated switch.  The unit needed to be fairly small and wired into the underside of some kitchen cabinets.  When touched, a string of fluorescent or LED lights, mounted under the cabinets, would turn on.  The total light power is less than 100 watts.  The system into two parts.  (1) A relay is mounted inside a plastic junction box and (2) a touch switch module.    Four wires leading from plastic junction box would connect to a second box containing the touch switch module.  The circuit is a simple relay driver powered by a9v battery. . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 20 Nov 2011

Touch Alarm for Door Knob I designed this hobby circuit many years ago and it seems be a very popular construction project.  Many companies offer simple alarm devices for personal use in bedrooms or hotel rooms.  A metal chain attached to a box holding the electronics is place . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2000

Touch and/or Remote Controlled Light Dimmer Old-fashioned light dimmers with knobs are passe! This one dims up or down at a touch or you can use an infared remote control.___ SiliconChip

Touch and/or Remote Controlled Light Dimmer-Part 2 Completing the construction and building the touchplate and pushbutton dimmer extensions.___ SiliconChip

Touch Controlled Mute Switch with 555 IC Here is another simple circuit to mute the volume of Audio devices through simple touch.  It exploits the action of the flip-flops in the timer IC 555 to reduce the volume of the Audio amplifier. IC NE555 is designed in the toggle mode.  Its lower and upper comparator inputs are connected to the touch plates which can be __ Designed by D Mohankumar

Touch Dimmer By simply touching this touch dimmer you can increase the light intensity of incandescent lamps in three steps.  The touch dimmer is built around 8-pin CMOS IC TT8486A/TT6061A specifically manufactured for...___ Electronics Projects for You

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 sensistive touchpad This board layout was created using the SOIC version of a PIC16F627A 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 TIC206D TRIAC, it enables smooth regulation of light intensity from a bulb of 10W – 400W.  A coil of 100µH/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 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 David A. 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 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 triggered alarm No description available __ Designed by Jospfh

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-controlled Dimmer Here’s a dimmer that, besides being touch-controlled, also has a setting memory that enables it, for example, to turn the lighting on at the level you had set last time it was turned off.  The project uses a specialized IC, an LS7534 from LSI Computer Systems, available from Farnell, among othersmust register on this site __ Designed by Published in Elecktor July/Aug, 2010

Touch-Plate Doorbell This touch-plate doorbell makes use of enhancement-mode MOSFETs forming part of CMOS quad NAND gate CD4007B in conjunction with a detector and Darlington driver stage. IC CD4007B comprises a dual complementary pair...___ Electronics Projects for You

Touch-Sensitive Audio Desk Trays 23-May-14 -Design News:   This Christmas, I received a MaKey MaKey , which turns everyday conductive objects into keyboard buttons.  Seeing as it runs on top of Arduino, I wanted to explore the same touch-sensitive capabilities on my Arduino Uno.  These trays, unlike normal trays with printed labels, have audio labels.  The __   Gadget Freak-Case #255

Touch-Sensitive Musical Bell with Timer This circuit is built around CMOS IC CD4011 and popular melody generator IC UM66. When touch plates are bridged by hand for a moment. the circuit starts to generate music. After __   01/01/07EFY


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