Touch Sensor - Online Article


Perhaps the most commonly used of all robotic sensors, the "touch sensor" is nothing more than a simple electrical switch; when the lever is pressed an electrical circuit is completed. Touch sensors were used in making Sciborg's bumpers. Chimera used touch sensors in its head (to tell when it was being petted) and its tail (to tell when it was being pulled.) Touch sensors are also useful as "limit switches", to indicate when some mechanism has reached the end of its travel.


A Simple Touch Switch



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 would not last, such as wet or very dusty areas.


  1. C1 - 10uF 16V Electrolytic Capacitor
  2. R1, R2 2 - 100K 1/4 Watt Resistor R3 - 10 Meg 1/4 Watt Resistor
  3. U1 - 4011 CMOS NAND Gate IC
  4. MISC - Board, Wire, Socket for U1


  1. The contacts can be made with just two loops of wire close together, or two squares etched close together on a PC board.
  2. When activated, the output of the circuit goes high for about one second. This pulse can be used to drive a relay, transistor, other logic, etc.
  3. You can vary the length of the output pulse by using a smaller or larger capacitor for C1.

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Shamit Kumar Tomar on 2008-08-04 20:18:26 wrote,

Where can we get the specified parts and what is the estimated cost of this setup.