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

Capacitance Switches:   #'s - O       P - Z
 

Last Updated: December 31, 2017 06:47 AM

Circuits Designed by Dave Johnson, P.E. :
1.5V 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.. . . Circuit by Dave Johnson P.E.-January, 2002

12v Touch Switch Exciter Circuit This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits.    It can support a cable length of about 2500 feet.    A typical remote switch circuit is also shown as well as a receiver circuit for those switches.. . . Circuit by David A. Johnson P.E.-February, 2002

3v Capacitance Proximity Switch This circuit was designed to provide a touch activated switch function without an external power supply.  It draws so little power that a single 3v battery will operate the circuit for many years. . . Circuit by Dave Johnson P.E.-February, 2002

5 Volt Momentary Operation 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. . . Circuit by David A. Johnson P.E.-March, 2002

5v Capacitance Touch Activated Momentary Switch This circuit is discussed in more detail in the section on Capacitance Proximity Switch Technology.  The circuit is powered from a standard +5v supply.  It has both a source and sink output that change state whenever a metal button connected to the circuit. . . Circuit by David Johnson P.E.-July, 2000

5v 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 A. Johnson P.E.-March, 2002

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

Capacitance Proximity Switch-3 volts This circuit was designed to provide a touch activated switch function without an external power supply.  It draws so little power that a single 3v battery will operate the circuit for many years . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

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Capacitance Touch Activated Momentary Switch-5v This circuit is discussed in more detail in the section on Capacitance Proximity Switch Technology.  The circuit is powered from a standard +5v supply.  It has both a source and sink output that change state whenever a metal button connected to the circuit . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2000

Capacitance Touch 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 . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2002

Door Knob Alarm 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 placed around the inside doorknob of a wood door.  Anyone grabbing the knob from the outside is detected. . . Circuit by Dave Johnson P.E.-May, 2000

Exciter Circuit-12v Touch Switch This circuit generates a 20KHz pseudo sine wave signal that can power approximately 50 remote touch activated switch circuits.  This hobby circuit can support a cable length of approximately 2500 feet.  A typical remote switch circuit is also shown as . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Finger 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. . . Circuit by Dave Johnson P.E.-June, 2000

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

Momentary Operation 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. . . Circuit by Dave Johnson P.E.-March, 2002

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 David Johnson P.E.-January, 2002


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

1.5V 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.. . . Circuit by Dave Johnson P.E.-January, 2002

101 Seconds Duration On Switch with Touch Control This is a touch control switch which keeps the circuit on about 100 seconds after touching the plate connected to the 2 numbered pin.  At the end of this time duration, relay releases and the circuit gets to off position.  The impedance of the trigger input of the 555 timer IC is very high and the inductive voltage on the human body is enough to trigger it.  The circuit works based on this principle. __

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

12v Touch Switch Exciter Circuit This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits.    It can support a cable length of about 2500 feet.    A typical remote switch circuit is also shown as well as a receiver circuit for those switches.. . . Circuit by David A. Johnson P.E.-February, 2002

240VAC Touch Switch This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load. . . Circuit by David Johnson P.E.-July, 2006

24v NiMH
Battery Charger using a 12v Solar Panel 
A while back I received an email from a guy in the UK.  He wanted to use a small solar panel, designed to charge 12v lead acid batteries, but use it to charge a 24v battery pack.  His 24v battery pack used 20 AA size NiMH
cells.  He went on to explain that his 20 cell NiMH
battery pack was used very infrequently . . . Hobby Circuit designed by David Johnson P.E.-October, 2011

3v Capacitance Proximity Switch This circuit was designed to provide a touch activated switch function without an external power supply.  It draws so little power that a single 3v battery will operate the circuit for many years. . . Circuit by Dave Johnson P.E.-February, 2002

5 Volt Momentary Operation 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. . . Circuit by David A. Johnson P.E.-March, 2002

5v Capacitance Touch Activated Momentary Switch This circuit is discussed in more detail in the section on Capacitance Proximity Switch Technology.  The circuit is powered from a standard +5v supply.  It has both a source and sink output that change state whenever a metal button connected to the circuit. . . Circuit by David Johnson P.E.-July, 2000

5v 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 A. Johnson P.E.-March, 2002

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

Basement Remote Doorbell This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Capacitance-Based Touch Switch This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Capacitance Proximity Switch-3 volts This circuit was designed to provide a touch activated switch function without an external power supply.  It draws so little power that a single 3v battery will operate the circuit for many years . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Capacitance Touch Activated Momentary Switch-5v This circuit is discussed in more detail in the section on Capacitance Proximity Switch Technology.  The circuit is powered from a standard +5v supply.  It has both a source and sink output that change state whenever a metal button connected to the circuit . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2000

Capacitance Touch 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 . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2002

Capacitive Sensor Special design for shop-windows animation; Useful for many types of touch controls __ Contact: Flavio Dellepiane, fladello @ tin.it

Capacitive Touch Switch Uses CPLD 05/29/08  EDN-Design Ideas Using an Altera MAX IIZ CPLD, you can implement a touch-switch decoder with no external components__ Circuit Design by Rafael Camarota, Altera, San Jose, CA

Cheap Touch Switch Using Transistor This cheap touch switch circuit is the touch switch is updated from the original version.  Which use IC to control the operation cause difficut for the electronics beginner.  So this circuit is thought to are suitable because uses TR purely.  When was broken also a simple repair.  and More cost-effective equipment.  But The application is __

Circuit Project: 12v Touch Switch Exciter This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits.  It can support a cable length of about 2500 feet.  A typical remote switch circuit is also shown as well as a receiver circuit for those switches.  Circuit diagram Source: DiscoverCircuits __

Detector for Human Footsteps This circuit uses a surplus geophone to detect human footsteps from 100 feet away.  It was designed for monitoring the Mexico/USA border.  This preamp part of the system draws about 50 micro amps from a 12 volt supply . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Door Knob Alarm 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 placed around the inside doorknob of a wood door.  Anyone grabbing the knob from the outside is detected. . . Circuit by Dave Johnson P.E.-May, 2000

Door Knock Beeper In some apartment buildings and homes, not equipped with a door bell, it may be hard to hear someone knocking on the front door.  The circuit below provides a means to activate a loud beeping sound inside, whenever someone knocks on the door. . . Circuit by David A. Johnson P.E.-June, 2009

Electronic Touch Switch Mechanical contacts have the disadvantage that they wear out.  That is why it is practical to use an electronic ‘touch switch’ in some situations.  With such a touch switch the resistance of the human skin is used for the switching action.  The schematic shows the design of a circuit that senses the resistance of the __

Exciter Circuit-12v Touch Switch This circuit generates a 20KHz pseudo sine wave signal that can power approximately 50 remote touch activated switch circuits.  This hobby circuit can support a cable length of approximately 2500 feet.  A typical remote switch circuit is also shown as . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Fastest Finger First This project describes a "Fastest Finger First" system that is cheap to build, has high noise immunity, is reliable and is also extensible.  Note that whilst the schematic below may look complicated, its actually a very simple & cheap interlock based round a single 4013 dual d-type flip-flop and an output driver that is replicated for each positionin this example, 8 times.  The buzzer is also optional and can be omitted, along with all its associated components.  The few extra resistors & capacitors used for improving the noise immunity are very cheap but improve the reliability of the design greatly.  i.e.  it's a proper design rather than a hack! __ Designed by Nick de Smith

Fastest Finger First Indicator Quiz-type game shows are increasingly becoming popular on television these days.  In such games, fastest finger first indicators (FFFIs) are used to test the player’s reaction time.  The player’s designated number...___ Electronics Projects for You

Fastest Finger First Indicator The above image shows the circuit diagram of Fastest Finger First Indicator which is used to make the project and has been taken from EFY.  This project is an electronic quiz buzzer that is affordable by the colleges and even individuals.  This project is useful for a 4-team quiz contest, although it can be modified for more number of teams.  Use this report for your reference and study only and thanks to all authors. __ Designed by Krity Vats, Divya Uniyal, Garima Sharma

Fastest Finger First System using Raspberry Pi Fastest finger first systems are used in school, college and TV contests.  The team which presses their push-button switch first is entitled to answer the query.  When two or more teams...___ Electronics Projects for You

Finger 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. . . Circuit by Dave Johnson P.E.-June, 2000

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

Hum-Sensitive Touch Alarm Radiation signals from mains wiring can travel a few metres of distance.  These can be induced by the electromagnetic field in the human body also.  This touch-sensitive alarm is based on generation...___ Electronics Projects for You

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

Jeopardy (Fastest Finger First) This project describes a "Fastest Finger First" system that is cheap to build, has high noise immunity, is reliable and is also extensible.  Note that whilst the schematic below may look complicated, its actually a very simple & cheap interlock based round a single 4013 dual d-type flip-flop and an output driver that is replicated for each positionin this example, 8 times.  The buzzer is also optional and can be omitted, along with all its associated components.  The few extra resistors & capacitors used for improving the noise immunity are very cheap but improve the reliability of the design greatly.  i.e.  it's a proper design rather than a hack! __ Designed by Nick de Smith

Knocking rings Doorbell In some apartment buildings and homes, not equipped with a door bell, it may be hard to hear someone knocking on the front door.  The circuit below provides a means to activate a loud beeping sound inside, whenever someone knocks on the door . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2009

Momentary Operation 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. . . Circuit by Dave Johnson P.E.-March, 2002

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 David Johnson P.E.-January, 2002

ON OFF Touch Switch with 555 This ON OFF touch switch circuit is based on the well known timer IC 555 (IC1), which drives a relay that acts like a switch.  The metal surfaces can have what form we want, but it should be clean and very close to the circuit. __ Designed by Popescu Marian


Capacitance Switches:   #'s - O       P - Z


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