SunFounder Thales Kit, Manual

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SunFounder Thales Kit for Raspberry Pi Pico, Release 1.0
RT = RN * expB(1/TK – 1/TN)
• RT is the resistance of the NTC thermistor when the temperature is TK.
•
RN
is the resistance of the NTC thermistor under the rated temperature TN. Here, the numerical value of RN is
10k.
• TK is a Kelvin temperature and the unit is K. Here, the numerical value of TK is 273.15 + degree Celsius.
• TN is a rated Kelvin temperature; the unit is K too. Here, the numerical value of TN is 273.15+25.
• And B(beta) , the material constant of NTC thermistor, is also called heat sensitivity index with a numerical
value 3950.
• exp is the abbreviation of exponential, and the base number e is a natural number and equals 2.7 approximately.
Convert this formula TK=1/(ln(RT/RN)/B+1/TN) to get Kelvin temperature that minus 273.15 equals degree Celsius.
This relation is an empirical formula. It is accurate only when the temperature and resistance are within the effective
range.
Example
Thermometer
2.2.8 Transistor
Transistor is a semiconductor device that controls current by current. It functions by amplifying weak signal to larger
amplitude signal and is also used for non-contact switch.
A transistor is a three-layer structure composed of P-type and N-type semiconductors. They form the three regions
internally. The thinner in the middle is the base region; the other two are both N-type or P-type ones – the smaller
region with intense majority carriers is the emitter region, when the other one is the collector region. This composition
enables the transistor to be an amplifier. From these three regions, three poles are generated respectively, which are
base (b), emitter (e), and collector (c). They form two P-N junctions, namely, the emitter junction and collection
junction. The direction of the arrow in the transistor circuit symbol indicates that of the emitter junction.
• P–N junction - Wikipedia
Based on the semiconductor type, transistors can be divided into two groups, the NPN and PNP ones. From the
abbreviation, we can tell that the former is made of two N-type semiconductors and one P-type and that the latter is
the opposite. See the figure below.
20 Chapter 2. What is Included in This Kit