Museum Technology Source KD-3 Proximity Switch - Manual (Page 2)

Museum Technology Source Inc.
PRELIMINARY INFORMATION--SUBJECT TO CHANGE
June 2012
Museum Technology Source Inc.
323 Andover Street Wilmington MA 01887
800-729-6873 | 978-657-3898
fax 978-657-7132
www.museumtech.com
Preliminary Specifications
Principle of Operation: Change in electrical capacitance
Sensing range: Depending upon sensor size and shape up to
10 inches (250 mm)
Response time: Typically 0.1 second or less
Calibration: Automatically calibrates to installed environment
Input-Output: 4 position 5.08 mm pluggable terminal
Output: Normall open relay, 24 Volt, 1 Amp rating
Power: 9 to 24 Volts DC, 10 mA standby, 70 mA active
2.1 mm jack
Power Input reverse polarity protected
Protection: Passes JESD22-A114 Electrostatic Discharge
Sensitivity Testing, Human Body Model (HMB)
+ / - 2000 Volts
Passes JESD22-A115 Electrostatic Discharge
Sensitivity Testing, Machine Model (MM)
Possible Sensor Shapes
KD-3 Proximity Switch
Principle of Operation
The KD-3 operates on the basis of detecting a change in the electrical capacitance between the sensor plate and the trigger-
ing object, which is usually the human hand. The capacitance of the sensor plate is constantly being compared to an internal
reference. When the capacitance increases as a hand approaches, a threshold, set by the internal reference, is exceeded
and the output switches on.
The internal reference automatically adjusts to take into account changes in humidity, or dirt on the sensor. This helps
ensure long-term reliability.
The sensor plate may take almost any shape or form, and may be placed behind plastic, glass or other matertial that does
not conduct electricity. The sensor may be molded into an object, thus when the object is touched the output activates.
The sensor plate should connect to the KD-3 with as short a wire as possible. In general, a lead wire of twelve inches or less
works fine. For greater distances, coaxial cable should be used for distances up to several feet.
The KD-3 is to some degree sensitive to the speed of the hand as it approaces the sensor. Extremely show movement may
result in the hand not being detected. However, experience shows that the user intuitively and quickly adapts to the behavior
of the KD-3