What are the characteristics of UJT?
The special features of a UJT are :
- A stable triggering voltage (VP)— a fixed fraction of applied inter base voltage VBB.
- A very low value of triggering current.
- A high pulse current capability.
- A negative resistance characteristic.
- Low cost.
What are the terminals of a unijunction transistor?
We have seen that a Unijunction Transistor or UJT for short, is an electronic semiconductor device that has only one p-n junction within a N-type (or P-type) lightly doped ohmic channel. The UJT has three terminals one labelled Emitter (E) and two Bases (B1 and B2).
What makes PUT programmable?
It is called programmable because the parameters like intrinsic standoff ratio (η), peak voltage(Vp) etc can be programmed with the help of two external resistors. In a UJT, the parameters like Vp, η etc are fixed and we cannot change it.
Why UJT is called Unijunction Transistor?
Construction of UJT The terminal of this junction is called emitter terminal (E). Since the device has three terminals and one pn-junction, for this region this is called as a Unijunction Transistor (UJT).
How many terminal are there in unijunction transistor?
Uni Junction Transistor (UJT): The uni-junction transistor is a solid-state three-terminal device that can be used in gate pulse, timing circuits, and trigger generator applications to switch and control both thyristors and triacs for AC power control type applications.
How many terminals does a programmable unijunction transistor PUT have?
Detailed Solution. It has a four-layered construction just like the thyristors and has three terminals named anode(A), cathode(K), and gate(G) again like the thyristors. It is called a programmable UJT just because its characteristics and parameters have many similarities to that of the unijunction transistor.
What does the term programmable mean as used in programmable Unijunction Transistor?
What are the terminals of a Unijunction Transistor?
How do you identify thyristor terminals?
SCR terminals may be identified by a continuity meter: the only two terminals showing any continuity between them at all should be the gate and cathode.
What are the characteristics of unijunction transistor (UJT)?
The Unijunction Transistor (UJT) will act as voltage breakdown device, when the input applied between emitter and base 1 reduces below breakdown value i.e., RB1 increases to a higher value. This shows that RB1 depends on the emitter current and it is variable. The characteristics of Unijunction Transistor (UJT) can be explained by three parameters:
What is programmable unijunction transistor (put)?
The programmable unijunction transistor is a device that overcomes the major disadvantages of the UJT. This article covers construction, basic operation, and characteristics of Programmable Unijunction Transistor.
What are the characteristics of the curve of the UJT?
Characteristics Curve of Unijunction Transistor (UJT) 1 Cutoff. Cutoff region is the area where the Unijunction Transistor (UJT) doesn’t get sufficient voltage to turn on. 2 Negative Resistance Region. When the transistor reaches the triggering voltage, V TRIG, Unijunction Transistor (UJT) will turn on. 3 Saturation.
What is the schematic symbol for unijunction emitter current vs voltage?
The schematic symbol is Figure (c) The Unijunction emitter current vs voltage characteristic curve (Figure (a) below ) shows that as V E increases, current I E increases up I P at the peak point. Beyond the peak point, current increases as voltage decreases in the negative resistance region.