P-doped (Annode), N-doped (Cathode), depletion region in the middle
Anode and Cathode (on test)
Annode to plus and cathode to minus is forward bias.
Reverse bais no current flow (unless really big!)
Cathode has a stripe (on test) Stripe to minus!
Rectifiers and Bridges
a single diode can be used as a half-wave rectifier to convert AC into <50% duty cycle DC.
4 diodes in a bridge configuration ("Bridge Rectifier") make a full-wave rectifier to convert AC into <100% duty cycle DC.
A rectifier is just a fancy word for a diode being used to convert AC into DC.
Reversed biased and Zener Diodes (but not on the tech test)
Zener Diodes are designed to have a precise breakdown or zener voltage (reverse bias) for use as a voltage regulator for small loads. Typical forward bias is 1 volt. Reverse bias is the Zener voltage (V-sub-Z), typically some voltage you want such as 3.3 volts.
Typical use is in a "Classic" Zener Voltage Clamping circuit with a zener diode (reversed biased) and a series resistor before the load to "regulate" down to the zener voltage.
handles power better
Works at higher frequencies
A Schottky diode is often used at the output of a power supply to insure against damaged due to reverse connections.
Photodiodes change bias based on the amount of light present
Power Supplies for Grow Lights -- Sine Waves prevent harmonics!!
Diodes are very often used to limit damage from unexpected spikes in voltage. Transient-voltage-suppression (TVS) diodes are specialty diodes, kind of like zener diodes — lowish breakdown voltages (often around 20V) — but with very large power ratings (often in the range of kilowatts). They're designed to shunt currents and absorb energy when voltages exceed their breakdown voltage. Used with flyback transformers or motors during startup.