What does LED / PT mean when defining electronics parts?

I know that LED means Light Emiting Diode but what is the PT?
these are used for TACH monitoring in a roomba.
Just wondering what PT stand for?
I know that the LED produces a signal on one side of a wheel and the PT senses the signal so as to monitor the speed of the robot. just dpnt know what PT stands for..

Light Emitting Diodes. It is a simple PN junction in a clear casing. It grows when current is passed though

3 Responses to “What does LED / PT mean when defining electronics parts?”

  1. Cindy Says:

    Cindy Crawford
    References :

  2. VicValentino Says:

    Light Emitting Diodes. It is a simple PN junction in a clear casing. It grows when current is passed though
    References :

  3. chris Says:

    Platinum Resistance Temperature sensors on a 1206-sized surface mount chip are now available from UK Switching & Sensing specialist, Willow Technologies Ltd. Designed, developed and manufactured by Sensotherm GmbH the sensors provide high accuracy, excellent long-term stability and a near linear output over the operating temperature range ?50 to +150C.

    The sensors may be pre-aged by temperature cycling to provide a maximum long-term drift of 0.02% over the full temperature range. Available as 100 & 500 devices, the sensors are laser trimmed to standard tolerance bands with a positive temperature coefficient compliant with DIN EN 60751 specifications.

    The sensors may be supplied blister-taped & reeled compatible with latest automated insertion techniques. Applications are wide and the devices make an excellent replacement for thermistors in most temperature measurement or compensation circuits.

    hope this helps
    References :
    http://www.willow.co.uk/html/pt_sensor.html
    http://en.wikipedia.org/wiki/Resistance_thermometer

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