Electrical Engineering ⇒ Topic : Mutual or Transfer Characteristics

Mutual or Transfer Characteristics

To plot the mutual or transfer characteristics the following procedures are performed:

• Maintain constant plate voltage
• Vary grid voltage
• Note the plate current

The mutual characteristics of a triode valve is shown in Figure (a) for different plate voltages.

If the grid is made more positive, plate current will get increased. At a certain grid voltage,the plate current will not change. If plate voltage is increased further, there will be no change of plate current.

From Figure (a), it is clear that when grid potential is zero, some electrons will flow towards the plate through the grid. So some plate current will be obtained.

If the grid is now given a negative potential nearer to the filament, there will be repulsive force on electrons. So plate current will decrease. If a grid voltage is made more and more negative, plate current will decrease and at a certain grid voltage, plate current will be zero. This grid voltage is called cut-off voltage and is defined as the minimum value of negative grid voltage required to reduce the plate current to zero

                                          Figure (a)  Mutual or transfer characteristics.