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TRANSISTOR BREADBOARD PROJECT |
V. Ryan © 2002 - 2022 |
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Components:
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PIN LAYOUT OF NPN TRANSISTOR |
1. Build the
breadboard circuit shown above. This is a dark sensor and relies on
several components, in particular the transistor. When the LDR is
covered the LED will light, although there may be a need to alter the
setting of the preset resistor. How it works: When light shines into the LDR its resistance is high and consequently current cannot flow from positive 9 volts to negative 0 volts. If the LDR is completely covered its resistance falls dramatically. Current then flows into the base of the transistor switching it on. Consequently current can flow through the collector and emitter - therefore, the LED lights. 2. Try building a light sensor, that is a circuit in which the LED lights if light shines into the LDR. HINT; try swapping round the LDR and the preset resistor. 3. Try building a similar circuit but this time add an arrangement of transistors called a Darlington Pair. Do you find any difference in the operation of the circuit ? 4. Try building a similar dark sensor but this time with a relay rather than an LED. |
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