05/11/2015 Activity 29 Transistors Aim To investigate the switching action of an npn transistor. Method – Follow the instructions on Activity 29. Result The transistor switches on at approximately ___ V COPY Date, Heading and Aim into your jotter.

How does the circuit work? Temperature around thermistor INCREASES Resistance of the thermistor DECREASES Voltage across the thermistor DECREASES Voltage divider circuit, so voltage across the variable resistor INCREASES to a value that will switch the transistor on….approximately 0.7 V. This allows current to flow through the LED and it lights up.

05/11/2015 Transistors Open up your notes at page 29, note 38. witch voltage transistor field

oltage evice 0.7 evice

supply light 0.7 transistor LED

HDRHDR eat ecreases esistance increases 1.8 Von motor R TH

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