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Description        Features        Applications        Specifications        Typical Connections   

Faraday Switches
Max Input Capacitance = 250pF

Model FS3X-1 Description

Faraday Switch, Model FS3X, externally powered

The module uses an electronic circuit to detect when an electrically conductive object comes in direct or near contact with the capacitance "cap" input.  A human, touching a metal button or approaching a metal sensing plate connected to the cap input, increases the capacitance between the module and a nearby earth ground.

When the capacitance exceeds a specific level, the module circuit activates a transistor switch. A multi-turn adjustment screw on the module is used to set the minimum capacitance needed to activate the switch. When carefully adjusted, the unit will switch with only a small capacitance change.

The module contains two switch outputs. The "momentary" output will remain activated as long as the sensor input capacitance is higher than the level set by the module’s adjustment screw. The "latched" output toggles the output on and off with each cap input activation. The module’s outputs can sink up to 1 amp of current and handle voltages up to 30v.

Faraday Switches use true capacitance sensing methods. Unlike some “AC hum-type” touch activated switch circuits, Faraday Switches do not require the area around the switch to be rich in line-powered devices, such as fluorescent lamps. However, to insure reliable operations, an earth ground reference does need to be established. Each module provides a terminal for an earth ground reference. The FS3X-1 model is an externally powered. A screw terminal is included for an external battery or power supply connection. The FS3X-1 model has an extended 250pF maximum capacitance capability. This switch is ideal for applications with a large installed capacitance.

The switch module is packaged in an epoxy sealed plastic box that is available with or without mounting feet. Standard barrier type screw terminals are provided to make all of the electrical connections. Dimensions are 1.0" x 1.0" x 0.75"

Faraday Switch Features
  • FS3X-1 is powered by an external supply ranging from 3v to 30v

  • Very low 4ua current drain

  • 100% solid-state circuitry 

  • True capacitance sensing, not “Hum”

  • Adjustable capacitance sensitivity

  • 1pF capacitance change detection

  • Transistor switch output, 1 amp, 30v

  • Excess of 10 million operations

  • Screw type terminals for easy wiring

  • Adhesive pad mounting (standard)

  • Cases with mounting feet (optional)

  • External power supply overrides battery

Also available is Model FS3N
which is powered by a 3v Lithium Battery

Faraday Switch Typical Applications
  • Replacement for pushbuttons

  • Finger touch activated

  • Hand, arm or foot proximity

  • Hidden behind walls or floors

  • Vandal-proof and weatherproof

  • Interactive museum displays

  • Automotive touch activated

  • Jail light or intercom controls

  • Liquid level monitors

  • Animal detection

  • Robotics PLC interface sensors

  • Material handling monitors

  • Touch free flush toilets

  • Computer Interface

Faraday Switch Specifications

Enclosure = 1.0”W x 1.0”L x 0.75”H

Electrical Connections = 5 screw barrier type terminal block

Supply voltage range = 3v30v

Typical Supply Current = 4ua @ 3v-15v, 1.5mA @ 30v

Minimum Momentary Output Switch Pulse Length = 100mS

Minimum Capacitance change duration for switch detection = 50mS

Minimum Capacitance change needed to activate switch = 1pF

Maximum Input Capacitance = 250pF

Output Switch = normally open, current sink, momentary & latch outputs

Maximum Switch Current = 1 amp

Maximum Switch Voltage (sinking output) – 30v

Operating Temperature = -40C+60C

Switch Life = excess of 10 million operations

Typical Faraday Switch Connections
FS3X-1 Faraday Switch Connention with Sinking Logic Circuit FS3X-1 Faraday Switch Connection with Alternation Relay Action

Faraday Capacitance Proximity Touch Switches Six (6) Models Available           Prices           Place an Order           Project Photos

David A. Johnson, P.E.

Consulting Electronics Engineer

6601 County Road 6410    Lubbock, TX  79416-9717

Phone:  806-778-8407  Central Time Zone

email: dave@discovercircuits.com                    
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Last Updated on: 22 November, 2021 02:42:39 PM

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