The Door Buzzer
- In this project you're going to make an electronic door buzzer, like the one shown below.
- To activate the buzzer and the LED, we're going to use a circuit component called a transistor.
- In this lesson you'll learn what a transistor is and how it can be used as an electronic switch
- Transistors come in many shapes and sizes, but they all have one thing in common.
- All transistors have three legs - a collector, a base and an emitter.
- The type of transistor you're going to be using is a BC547B, which looks like this.
- Use online resources to help you label the picture above, to show which legs are which.
- The circuit symbol for a transistor looks like this.
- The legs have been labelled B,C and E.
- Now look at the simulation below. This shows a transistor connected to a 5V Power supply, with an LED.
- Connected to the
base of the transistor is a signal generator.
- The signal generator produces a varying voltage, going from 0 up to 5V and then back down again.
- The voltmeter will tell you the voltage being produced by the signal generator.
- Copy an image of the BC547B transistor and label each pin.
- In the circuit above, try and explain what is causing the LED to switch on and off again.
- Make sure your are using the following terms:
- Signal Generator
- Your badge will be awarded by the quality of your explanation to the circuit above.
- The silver badge must include the diagram.
- Silver - A reasonable attempt at an explanation of the circuit plus labelled image of BC547B
- Gold - A correct explanation that uses the term base, collector and emitter.
- Platinum - A detailed explanation using all the terms from the badge task