What is a Diode?

A diode is a semiconductor device that acts like a one-way street for electrical current—it allows current to flow in only one direction.

In a forward‑biased condition, the diode’s anode (its positive side) is at a higher voltage than its cathode. This allows current to pass through—just like a turnstile lets people go in only one direction.

In a reverse‑biased condition, the diode blocks current, similar to a locked door preventing movement in the wrong direction.

Real-World Examples:
- Rectification: Converting AC to DC for powering devices.
- Protection: Preventing reverse current in car electronics.
- Signal Demodulation: Filtering signals in radio receivers.

Diodes are essential for ensuring safe and reliable operation in almost all electronic devices.

The symbol above is drawn using p5.js. The triangle represents the anode (where current enters), while the vertical line represents the cathode (where current exits). Short legs extend from each side to indicate connection points.

What is a Zener Diode?

A Zener diode is designed to operate in reverse bias. When the reverse voltage exceeds a specific value—the Zener voltage—the diode conducts and clamps the voltage, thereby regulating the output.

Think of it as a safety valve that maintains a steady voltage by diverting excess energy.

Real-World Examples:
- Voltage Regulation: Stabilizing power supplies for sensitive electronics.
- Surge Protection: Clamping voltage spikes to protect devices.
- Reference Voltage: Providing a stable voltage reference in precision circuits.

Zener diodes are critical for building stable and reliable electronic systems.

The symbol above is drawn using p5.js. For a Zener diode, the triangle represents the anode and the cathode is drawn as a zigzag (Z‑shaped) line to denote its voltage‑regulation function.