Home » Electronics » The Diac Features & Applications

The Diac Features & Applications

Features of a Diac

The diac is a two-terminal, semiconductor, bi-directional switching device. It can conduct in both directions. The diac closely resembles a PNP transistor without an external base terminal.

Diac structure
Figure 1.0 Diac Structure
Diac Symbol
Figure 1.1 Diac Symbol

Operation of a Diac

The diac does not conduct except for a small leakage current) until the breakover voltage VS is reached, typically 20 to 40 volts. At that point the diac goes into avalanche conduction, furthermore, at that point the device exhibits a negative resistance characteristic and the voltage across the disc snaps back, typically about 5 volts, creating a breakover current IS in the order of 50 t 200 μA enough to trigger a triac or SCR.

Diac characteristics
Figure 1.2 Diac characteristics

Diac Applications

The negative resistance characteristic of the diac makes it valuable for very simple relaxation oscillators and pulse generators; however, its key application is in conjunction with a triac to produce AC phase-control circuits helpful for motor-speed control, light dimming and other AC power-control applications.

Also Read: The Junction Field Effect Transistors (JFET)

Please follow us & share:

Comments

2 responses to “The Diac Features & Applications”

  1. […] The Diac Features & Applications […]

Currently trending: