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Quick Release Push Plate Hex & LED RGB issue; Cool down no Green

A project log for Fitting Heat Bed warning RGB LED

To warn using colours of RGB LED that the that the heatbed is hot.

films4youFilms4You 07/21/2016 at 11:050 Comments

Quick Release Push Plate Hex & LED RGB issue

via @YouTube

Or watch the slow chainging back to "Green" Never really goes back to "Green"

It could be the position of "Cold Junction" of the sensor is causing this issue i.e. not changing as quick as it should when cooling down. I need to try to discover if the position of "Cold Junction" of the sensor causing this issue or if it is something else.


The LED RGB: I use this to indicate that the heat bed is too hot to touch.


The LED RGB is controlled by a Arduino Nano and a Precision MAX6675 Module + K Type Thermocouple Temperature Sensor.


It could be the position of "Cold Junction" of the sensor is causing this issue i.e. not changing as quick as it should when cooling down. I need to try to discover if the position of "Cold Junction" of the sensor causing this issue or if it is something else.


The position of the "Cold Junction" being in a warm place. In my Power Supply, RAMPS box.


Also I want to want to change the Arduino Nano code a small amount so that the RGB LED shows "Blue" if there is a problem, no connection, with the thermocouple, this is quite easy change in the code.


Some information about "Cold Junction"


The hot junction is the one that's actually measuring the temperature. The cold junction is an identical thermocouple that is not exposed to heat, but kept at a known temperature. This allows absolute temperature to be measured (by essentially subtracting out the cold junction temperature


MAX6675 Cold-Junction-Compensated K-Thermocouple-to-Digital Converter (0°C to +1024°C)


https://cdn-shop.adafruit.com/datasheets/MAX6675.pdf (PDF format), Adafruit


Other information about"Cold Junction"


https://www.maximintegrated.com/en/app-notes/index.mvp/id/4026


http://www.ti.com/lit/an/sloa204/sloa204.pdf (PDF format)


http://www.acromag.com/sites/default/files/How_to_prevent_temperature_measurement_errors_when_installing_thermocouple_sensors_and_transmitters_926A.pdf (PDF format)

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