Resistor
A resistor limits current and sets voltage/current behavior in a circuit. In student projects it often protects LEDs, creates pull-up or pull-down behavior, or forms a voltage divider.
Part images
What it is
A resistor limits current and sets voltage/current behavior in a circuit. In student projects it often protects LEDs, creates pull-up or pull-down behavior, or forms a voltage divider.
How students use it
Use a resistor in series with an LED, as a pull resistor for inputs, or paired with another resistor/sensor to make a voltage divider for analog readings.
Pins and power
Two non-polarized leads. Either end can face either direction.
Passive part. Choose a resistance and power rating that fits the circuit.
Color bands encode the resistance value. Four- and five-band resistors are common. A 220 ohm resistor is often used for LED current limiting in beginner circuits.
Voltage and safety
A resistor can reduce current, but it is not a magic 5V-to-3.3V adapter for every situation. For Pico inputs, verify the voltage at the GPIO pin.
If a resistor gets hot, the circuit is drawing too much current or the resistor power rating is too low.
Datasheet notes
Generic through-hole resistors are selected by resistance, tolerance, and power rating rather than a single module datasheet.
Common mistakes
Reading the color bands from the wrong end, using 220 ohm where 10k ohm was expected, forgetting the resistor in an LED circuit, and building a voltage divider with swapped values.