|
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.
.(designed by David A. Johnson) |
|
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. You can use a piece of metal as a plate. The circuit can be
used in toy circuits, buzzers or any project that is suitable. You can adjust the
duration time by changing the R1 and C1 values.
.(circuit design added 11/08) |
|
120vac Touch Switch - This is a capacitance based touch on/touch off switch, which
can control power to a 200 watt 120vac load.
.(designed by David A. Johnson) |
|
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.
.(designed by David A. Johnson) |
|
240VAC Touch Switch - This is another capacitance based touch on/touch off switch,
which can control power to a 200 watt 240vac load.
.(designed by David A.
Johnson) |
|
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. It is
discussed in more detail in the section on Capacitance Proximity Switch Technology.
(Note link is off site)
.(designed by David A. Johnson) |
|
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.
.(designed by David
A. Johnson) |
|
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 is touched. An earth ground
reference is required.
.(designed by David A. Johnson) |
|
Capacitive Sensor - Special design for shop-windows animation. Useful for
many types of touch controls. (electronic circuit added 06/07/08) |
|
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.....(design idea added 06/07/08) |
|
Doorknob 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 by the electrical capacitance change that occurs from the human
hand contact between the knob and the box. Almost all of the commercial devices sold
use a more expensive and power consuming radio frequency circuit approach to detect
the capacitance change. But, a very inexpensive and micro power technique can also
work. This circuit schematic should dramatically reduce the cost of the device and
allows it to operate for many years from one set of batteries.
.(designed by David A.
Johnson) |
|
Fastest Finger First Indicator - (electronic Circuit / Schematic added 10/04) |
|
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 is not desired.
.(designed by
David A. Johnson) |
|
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.
.(designed by David A. Johnson) |
|
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.
.(designed by David A.
Johnson) |
|
Touch Activated Alarm (Tony van Roon) - (schematic / circuit added 10/02) |
|
Touch Activated Lamp (Bowden) - (circuit / schematic design added 6/06) |
|
Touch activated timer switch extends battery life - 07/10/08 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.....(design idea added 09/08) |
|
Touch Dimmer - (electronic Circuit / Schematic added 10/04) |
|
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
.(added 05/08) |
|
Touch Switch (Aaron Cake) - 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....
(circuit added 08/08/08) |
|
Touch Switch (Randy Linscott) - 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
.(added 05/08) |
|
Touch Switch Circuits - 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....(electronic designs added 08/08/08) |
|
Touch Switch II -
.(electronic schematic added 08/08) |
|
Touch switch needs no DC return path - 02/03/05 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.....(design idea added 5/05) |
|
Touch Switch using Transistors - (Tony van Roon's circuit added 9/04) |
|
Touch Switches - (circuit added 9/04) |
|
Touch triggered alarm - No description available... |
|
Travel Touch Alarm - The Travel Touch Alarm can be used to provide a audible
alarm when someone touches the door knob or handle of your hotel room. The door
knob or handle must be made of metal for the circuit to work. The main chip in the
circuit is a 555 timer
.(added 08/08/08) |
