Transistors

The goal of this sequence of five activities is to explore different electrical components in order to better understand the more complex role of the transistor in circuits. Learners begin with a simple circuit to observe how resistors affect the brightness of an LED. Next, they add a switch to create an on-off circuit that controls when the LED turns on. In the third activity, learners replace the switch with a photoresistor to build a circuit that responds to changes in light. They then construct a smart light-sensitive circuit by adding a transistor, allowing the LED to turn on automatically in low-light conditions. In the last activity, learners build a circuit with two transistors and capacitors to make two LEDs blink alternately, providing a simple context to consider how components can be combined to create timed patterns of light.