Ujt firing circuit

The UJT has three terminals: an emitter (E) and two bases (Band B2). The base is formed by lightly doped n-type bar of silicon. Two ohmic contacts Band Bare attached at its ends.

The emitter is of p-type and it is heavily doped. The resistance between Band B when the emitter is open- circuit is called interbase .

If you want random firing you need to introduce some further circuit elements.

Like diodes, unijunction transistors are .

One common application of the uni junction transistor is the triggering of the other devices such as the SCR, triac etc. The resistor RE is chosen so that the load line determined by RE passes through the device characteristic in the negative . UNIJUNCTION TRANSISTOR ( UJT ) ! The connections at the ends of the bar are known as bases B1 . Thus the pulse is generated in the circuit. Now the capacitor discharges through the output resistance. When the capacitor voltage reaches peak point voltage of UJT.

Lab Experiment Aim To Study and verify UJT Triggering circuit of SCR. These pulses are generated across Rand are connected to the gate of the SCR. This can be viewed by see in the voltage drop . It includes UJT triggering, SCR (Silicon Controlled Rectifier), Load resistor. A unijunction transistor (UJT) is an electronic semiconductor device that has only one junction. Lujt based triggering circuit.

It is used in free-running oscillators, synchronized or triggered oscillators, and pulse generation circuits at low to moderate frequencies (hundreds of kilohertz). It is widely used in the triggering circuits for silicon controlled rectifiers. The low cost per unit, combined with its unique . Dynamic Turn ON Switching Characteristics. Features of R,RC,UJT,Triggering. LEARN AND GROW - Duration: 4:17.

SCRs is archive small variations in supply voltage and frequency are not going to effect the circuit operation. In case the resistor 'R' is reduced so that the capacitor voltage reaches UJT threshold voltage . Unijunction Transistor Oscillator - Duration: 6:28.