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More Sensors / Detectors:
Capacitance Sensors Circuits

 

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.,  01/18/02]

 

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.,  07/11/06]



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.,  02/10/02]

 

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.,  07/11/06]

 

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.,  10/12/11]

 

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.,  02/12/02]

 

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.,  03/12/02]

 

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.,  07/08/00]

 

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.,  03/12/02]

 

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.,  02/12/02]

 

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.,  07/11/06]

 

Capaciatance-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.,  07/11/06]

 

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.,  02/12/02]

 

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.,  07/08/00]

 

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.,  01/18/02]

 

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.,  07/11/06]

 

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.,  05/29/00]

 

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.,  06/14/09]

 

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.,  02/10/02]

 

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.,  06/03/00]

 

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.,  02/11/02]

 

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.,  07/09/06]

 

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.,  06/14/09]

 

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.,  03/12/02]

 

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.,  01/18/02]

 

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.,  07/09/06]

 

Short Range Reflective Object Sensor  -  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 Dave Johnson P.E.,  07/09/06]

 

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.,  02/07/10]

 

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.,  06/03/00]

 

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.,  11/07/10]

 

Through Glass Pushbutton 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 . . . [Hobby Circuit designed by David A. Johnson P.E.,  02/10/02]

 

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.,  01/18/02]

 

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.,  05/29/00]

 

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.,  02/12/02]

 

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.,  07/11/06]

 

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.,  02/11/02]


More Sensors / Detectors: Capacitance Sensors Circuits

Master Category List - Dave's Circuits


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


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