DIAC (Diode for Alternating Current) is like a TRIAC without a gate terminal. DIAC conducts current in both directions depending on the voltage connected to its terminals. When the voltage between the two terminals greater than the breakdown voltage, the DIAC conducts and the current goes in the direction from the higher voltage point to the lower voltage one. The following figure shows the layers construction, electric circuit symbol and the operating characteristics of the DIAC. Figure 1 shows the DIAC construction and electric symbol. Figure 2 shows a DIAC V-I characteristics.
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Figure1: DIAC construction and schematic symbol
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The DIAC used in firing circuits of thyristors since its breakdown voltage used to determine the firing angle of the thyristor.
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Figure2: DIAC V-I characteristics
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