Skills · skill
Building a Circuit on a Breadboard
Electronics · Beginner
- Difficulty
- Beginner
- Safety
- Low voltage; the only real risk is a shorted battery pack getting hot. Never breadboard mains.
- Done When
- The LED lights, the measured current is within 10 % of the calculation, and you can explain every part.
- Tools
- Breadboard, jumper wires, LEDs, resistors, a 5 V supply or battery pack, a multimeter to check.
- Category
- Electronics
- Summary
- Wiring a working circuit — an LED, a resistor, a supply — without solder, and understanding why every part is there.
Steps
Learn the board: the long rails run the length; the short rows of five are joined across.
Wire the supply to the rails; check with the meter before adding anything.
LED long leg (anode) toward positive, resistor in series on either side.
Calculate the resistor and use the nearest standard value above.
Power on: it lights. Measure the LED drop and the resistor drop; they add to the supply.
Measure the current in series and compare with what you calculated.
The Science
The LED is a diode: it conducts one way and drops a fixed voltage, about 2 V for red, 3 V for blue, set by the semiconductor's band gap — the photon energy, by the Planck–Einstein relation. Without a resistor it would draw whatever current the supply can give and die. Ohm's law sizes the resistor: (supply − LED drop) ÷ desired current, so 5 V, 2 V, 10 mA → 300 Ω. Kirchhoff's laws say the current is the same everywhere in the loop and the voltages add to the supply.
How It Fails
Nothing lights: LED backwards, or a part in a row that is not connected to what you think. LED flashes and dies: no resistor. Dim: resistor far too large.
Referenced by
element
equation
machine
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