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 |