See how a diode controls current direction
Blink a resistor-limited red LED through a forward-biased 1N4001 diode on D8.
Blink a resistor-limited red LED through a forward-biased 1N4001 diode on D8.
Use the Uno R3 Learning Kit. Build with power disconnected, check the labelled connections, then upload the supplied sketch. Drag or zoom the 3D model to inspect it from any angle.
Step 1 — Watch the complete build
Press Play for the narrated build. You can rotate and zoom the model while it plays, or follow the individual steps below.
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Keep U S B disconnected while you build. On this breadboard, each group of five holes shares a connection; the centre channel separates the two halves. You can drag the 3D view to look around. Connect Arduino ground to the ground rail. Add the 1N4001 rectifier diode. Its cathode lead goes into column 4 row E; the highlights show the remaining holes. Add the Red L E D · 5 millimetres. Its cathode lead goes into column 20 row E; the highlights show the remaining holes. Add the 1 kiloohm resistor. Its Pin 0 lead goes into column 10 row H; the highlights show the remaining holes. Connect Arduino digital pin 8 to one end of the resistor. Connect the other end of the resistor to the diode’s anode pin. Connect the diode’s cathode pin to the L E D’s anode lead. Connect the L E D’s cathode lead to the ground rail. Check all wiring. Connect the square U S B-B plug to the Uno and the U S B-A plug to your computer. Use Verify and Upload in the code editor below.
Step 2 — Understand the breadboard
Keep USB disconnected while you build. On this breadboard, each group of five holes shares a connection; the centre channel separates the two halves. You can drag the 3D view to look around.
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Keep U S B disconnected while you build. On this breadboard, each group of five holes shares a connection; the centre channel separates the two halves. You can drag the 3D view to look around.
Step 3 — Connect Uno GND → T- rail 1
Connect Arduino ground to the ground rail.
| Connect | To |
|---|---|
| Uno GND | T- rail 1 |
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Connect Arduino ground to the ground rail.
Step 4 — Place 1N4001 rectifier diode
Add the 1N4001 rectifier diode. Its cathode lead goes into column 4 row E; the highlights show the remaining holes.
Exact breadboard holes
- diode · cathode → column 4 row E
- diode · anode → column 8 row E
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Add the 1N4001 rectifier diode. Its cathode lead goes into column 4 row E; the highlights show the remaining holes.
Step 5 — Place Red LED · 5 mm
Add the Red LED · 5 mm. Its cathode lead goes into column 20 row E; the highlights show the remaining holes.
Exact breadboard holes
- led · cathode → column 20 row E
- led · anode → column 21 row E
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Add the Red L E D · 5 millimetres. Its cathode lead goes into column 20 row E; the highlights show the remaining holes.
Step 6 — Place 1 kΩ resistor
Add the 1 kΩ resistor. Its Pin 0 lead goes into column 10 row H; the highlights show the remaining holes.
Exact breadboard holes
- r · Pin 0 → column 10 row H
- r · Pin 1 → column 14 row H
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Add the 1 kiloohm resistor. Its Pin 0 lead goes into column 10 row H; the highlights show the remaining holes.
Step 7 — Connect Uno D8 → column 10 row J
Connect Arduino digital pin 8 to one end of the resistor.
| Connect | To |
|---|---|
| Uno D8 | column 10 row J |
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Connect Arduino digital pin 8 to one end of the resistor.
Step 8 — Connect column 14 row J → column 8 row A
Connect the other end of the resistor to the diode’s anode pin.
| Connect | To |
|---|---|
| column 14 row J | column 8 row A |
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Connect the other end of the resistor to the diode’s anode pin.
Step 9 — Connect column 4 row A → column 21 row A
Connect the diode’s cathode pin to the LED’s anode lead.
| Connect | To |
|---|---|
| column 4 row A | column 21 row A |
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Connect the diode’s cathode pin to the L E D’s anode lead.
Step 10 — Connect column 20 row A → T- rail 20
Connect the LED’s cathode lead to the ground rail.
| Connect | To |
|---|---|
| column 20 row A | T- rail 20 |
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Connect the L E D’s cathode lead to the ground rail.
Step 11 — Place USB-A to USB-B cable · Uno
Check all wiring. Connect the square USB-B plug to the Uno and the USB-A plug to your computer. Use Verify and Upload in the code editor below.
Loading assembly…
Check all wiring. Connect the square U S B-B plug to the Uno and the U S B-A plug to your computer. Use Verify and Upload in the code editor below.
Step 12 — Program your Uno
Choose Arduino Uno. Verify, pair the board and Upload this sketch. Keep USB connected. Blink a resistor-limited red LED through a forward-biased 1N4001 diode on D8.
Step 13 — Try it and troubleshoot
Power off, reverse only the diode and reconnect. The LED should stay dark because the diode blocks this current direction. Restore its original orientation afterwards.
If it does not work
The LED and the diode both have polarity. Keep the resistor in series. In the motor lesson the 1N4001 is instead placed across the motor as a flyback path.
Parts List
Required Parts (1)
Use the components named in this tutorial. A computer and any additional power supply are not included.
x1
$64.70
In stockProject Summary
1 part total
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