Step 2: Open Falstad simulation
Step 3: Questions
On a PNP transistor:
- Emitter: Input
- Base: Second output – turns on/off
- Collector: Primary output – provides current
When the base is provided a path to GND, the PNP transistor allows current to flow from the emitter to collector.
On an NPN, the base receives a small current (input) to allow current to flow from collector to emitter.
1. What happens when the resistor (10k) connected to A is removed?
2. Which ground, A or B, is drawing most of the current? (check Falstad)
3. If you replace the PNP with an NPN, the LED will not turn on. How can you turn the LED on by making a change to the A circuit (connected to base)?
4. What is the main difference between NPN and PNP transistors?