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Circuits designed by David Johnson, P.E.
Last Updated on:
Thursday, March 22, 2012 08:00 AM
Master Category List
- Dave's Circuits
Text & Graphics
Copyright © David A. Johnson, PE - ALL Rights Reserved.
LINKING to Dave's circuits is permitted but DO NOT COPY to your WEB SITE server! |
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Photo-Flash Circuits |
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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.
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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.
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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.
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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.
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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.
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9v POWERED XENON PHOTOFLASH CONTROLLER
This 9v battery powered circuit is designed for remote control flash needs. A charge
control circuit turns off the high voltage generator when the photoflash capacitor is
fully charged. A neon lamp is included to indicate when the system is ready to flash.
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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.
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LINE POWERED XENON FLASH TRANSMITTER
This line-powered xenon flash circuit drives a small camera type flash tube. It has an
optical isolator to allow the flash to be safely triggered from some remote device. A
flash rate of 2Hz is possible with the circuit.
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