Capacitance / Touch Switch Circuits Free Electronic Circuit Links
It features both a normally open and a normally closed set of solid-state switch thermals. It also has an adjustable sensitivity, which may be set for a touch capacitance change as small as 1 picofarad. . . . [Circuit by Dave Johnson P.E., 01/18/02]
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 top of this time duration, relay releases and the circuit gets to off position. The impedance of the trigger input of the 555 timer IC could be very high and the inductive voltage on the human body is sufficient to trigger it. The circuit works based on this principle. You should utilize a piece of metal as a plate. The circuit will be utilized in toy circuits, buzzers or any project that is suitable. You possibly can adjust the duration time by changing the R1 and C1 values. . . .
120 VAC Touch Switch – This can be a capacitance based touch on/touch off switch, which may 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 may power about 50 remote touch activated switch circuits. It might support a cable length of about 2500 feet. A typical remote switch circuit can also be 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 may 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 – Some time back I received an email from a guy within 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 clarify 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 supply 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 a few years . . . [Circuit by Dave Johnson P.E., 02/12/02]
5 Volt Momentary Operation Touch Switch – This straightforward 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 might 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 additional detail within the section on Capacitance Proximity Switch Technology. The circuit is powered from an ordinary +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 easy circuit uses a single IC to form a pleasant touch switch circuit. A single transistor forms the remote active switch sensor. Multiple switches could be wired in parallel. The switch circuit will be located about 500 feet from the control circuit . . . [Hobby Circuit designed by David A.