14 October 2017

Static and Dynamic Characteristics of the SCR

  • Figure A shows the circuit diagram to obtain V – I characteristic of the SCR
  • Here VAK is voltage between anode to cathode and Vg is gate voltage. 
  • The static V – I characteristic of the SCR is divided into following mode.

Structure, Equivalent circuit and Working of the SCR

  • The full form of the SCR is silicon controlled rectifier. 
  • It is a three junction, three terminal and four layer type PNPN semiconductor device. The terminals are anode (A), cathode (K) and gate (G).
  • It allows current flow only one direction so it is called as unidirectional device. 

12 October 2017

Speed Control of the DC Series Motor

  • The speed of the DC Motor is related to following equations
         N α Eb / Ф
         N = K ( V – IaRa ) / Ф
  • Therefore the speed of the DC Motor is controlled by varying

9 October 2017

Torque and Output Power Equation of the DC Motor

  • The term torque means ‘Turning movement of the force about an axis.’
        T = F × r Newton – meter
        Where T = Torque
                   F = Force in Newton
                    r = Radius in Meter

5 October 2017

UJT As Relaxation Oscillator

  • The UJT is often used in the timing and triggering circuits. 
  • Figure A shows the circuit diagram for the UJT relaxation oscillator.
  • When the switch S is kept closed, the capacitor C is charged through resistance R towards voltage VDC