What is inter Base resistance?
The resistance between B1 and B2 when the emitter is open-circuit is called interbase resistance. It is a current-controlled negative resistance device.
What is the typical value of the interface resistance of UJT?
If measured with an ohmmeter, this static resistance would typically measure somewhere between about 4kΩ and 10kΩ’s for most common UJT’s. The ratio of RB1 to RBB is called the intrinsic stand-off ratio, and is given the Greek symbol: η (eta). Typical standard values of η range from 0.5 to 0.8 for most common UJT’s.
What is the range of values of Interbase base 1 to base 2 resistance of a UJT?
UJT Operation The manner in which the device is manufactured is such that the interbase resistance, that is, the resistance between base 1 and base 2, is high. This value will be in the range 5 to 10 kΩ.
Which base in the UJT has a variable value?
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.
What is valley point in UJT?
The point on the current-voltage characteristic corresponding to the second lowest current at which dvAK/diA = 0 when the gate is biased from a resistive voltage divider.
Why is UJT known as a Unijunction Transistor?
Definition: Unijunction Transistor is a semiconductor switching device having 2 layers and 3 terminals and is abbreviated as UJT. It is called so because of the presence of only one junction. It has the ability to limit large power with a small input signal and is also known as a double base diode.
What is its value of resistance between B1 and B2?
Since the silicon bar is lightly doped, the resistance between B1 and B2 is very high (typically 5 to 10 KΩ). A heavily doped P-type region is constructed on one side of the bar close to the B2 region.
What is peak point and valley point in UJT?
Peak-Point Emitter Current. It represents the rnimrnum current that is required to trigger the device (UJT). It is inversely proportional to the interbase voltage VBB. Valley Point Voltage VVThe valley point voltage is the emitter voltage at the valley point.
Why is UJT known as a unijunction transistor?
What is peak point and valley point?
Peak-Point Emitter Current. It represents the rnimrnum current that is required to trigger the device (UJT). It is inversely proportional to the interbase voltage VBB. Valley Point Voltage VV The valley point voltage is the emitter voltage at the valley point. It increases with the increase in inter-base voltage VBB.
What is the inter base resistance of the UJT?
The equivalent circuit of the UJT is shown in the Figure B. The resistance between terminal base 1 and base 2 with emitter open is called as inter – base resistance ( RBB ). Therefore RBB = RB1 + RB2 The value of inter base resistance lies is in the range of 4.7 kilo ohm to 10 kilo ohms.
What is the intrinsic stand off ratio of an UJT?
The circuit action of a UJT can be explained more clearly from its equivalent circuit. (ii) If a voltage V BB is applied between the bases with emitter open, the voltage will divide up across R B1 and R B2. The ratio V 1 / V BB is called intrinsic stand-off ratio and is represented by η. The value of η lies between 0.51 and 0.82.
Which is the equivalent circuit of the UJT?
The equivalent circuit of the UJT is shown in the Figure B. The resistance between terminal base 1 and base 2 with emitter open is called as inter – base resistance ( RBB ). Therefore RBB = RB1 + RB2. The value of inter base resistance lies is in the range of 4.7 kilo ohm to 10 kilo ohms.
What is the structure and characteristic of the UJT?
The structure and symbol of the UJT is shown in the Figure A. The UJT consists of lightly doped N type silicon bar with terminal ends with base 1 ( B1 ) and base 2 ( B2 ). A small heavily doped P type material is alloyed to its one side for producing single PN junction.