If the semiconductor has a few per million atoms with FIVE outermost (valence) electrons....... FIVE valence atoms have an “extra” electron in the crystal.

If the semiconductor has a few per million atomswith FIVE outermost (valence) electrons ....

... FIVE valence atoms have an “extra” electron in the crystal structure.

The “extra” electron is NEGATIVELY charged.

Semiconductors

This is Called “N-TYPE”

If external voltage is applied:

Junction Diode

NEGATIVE to ANODE; POSITIVE to Cathode

The Depletion (Barrier) Zone is increased,BLOCKING CONDUCTION

Rectifier Filters

Moderate Load ....

Capacitor charges to Peak value as voltage rises,but discharges when voltage drops away.

Single-Phase Full-WaveBridge Rectifier

Back

Conduction DuringNegative ½ Cycle

Three-Phase Waveforms3-phase AC Features

Phase Voltages are 1200 out-of-phase

1200

2400

Three-Phase Half-Wave Rectifier

(Animated)

Three-Phase Half-Wave Rectifier

Maximum value = VPeak Minimum value = VPeakx0.5

VRipple = VPeak – (VPeak x 0.5) = VPeak x 0.5

Three-Phase Full-Wave Rectifier

Maximum value = VPeak Minimum value = VPeakx0.866

VRipple = VPeak – (VPeak x 0.866) = VPeak x 0.134

Voltage Regulator

THREE-TERMINAL REGULATOR(7xxx Series)

7812

Input

Output

Ground

Positive Output

7812

Regulated Voltage (12V)

Voltage Regulator

THREE-TERMINAL REGULATOR(7xxx Series)

7912

Input

OutputGro

und

7912

Regulated Voltage (12V)

Negative Output

Electronic Control Devices (Thyristors)

Silicon Controlled Rectifier (SCR)

Varying R1 varies charging rate of the Capacitor.

Animated

This varies the Trigger Point, controlling the average load current

Trigger Point can be delayed up to nearly 1800

Electronic Control Devices (Thyristors)TRIAC

Waveform across Load Waveform across TRIAC