CrazyEngineers Archive
Old, but evergreen and popular discussions on CrazyEngineers, presented to you in read-only mode.
@qaisarpk1 • 01 Apr, 2009
what is the reason of negative resistance in UJT . plz explain in some detail
@shiwa436 • 02 Apr, 2009 The UJT is biased with a positive voltage between the two bases. This causes a potential drop along the length of the device. When the emitter voltage is driven approximately one diode voltage above the voltage at the point where the P diffusion (emitter) is, current will begin to flow from the emitter into the base region. Because the base region is very lightly doped, the additional current (actually charges in the base region) causes conductivity modulation which reduces the resistance of the portion of the base between the emitter junction and the B2 terminal. This reduction in resistance means that the emitter junction is more forward biased, and so even more current is injected. Overall, the effect is a negative resistance at the emitter terminal. This is what makes the UJT useful, especially in simple oscillator circuits.
@g_rakesh2 • 02 Apr, 2009
The characteristics of UJT can be divided in three regions, cut-off region, negative resistance region and saturation region. The most important region is negative resistance region. Negative resistance region is the part of the characteristics where, as current increases voltage decreases.​
@sauravgoswami • 03 Apr, 2009 it is a phenomena which finds its application in RF devices and communication!!!
@qaisarpk1 • 04 Apr, 2009 thanx u all brothers

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