Contents
What are the limits of a transistor circuit?
The transistor can’t drive the collector to the emitter voltage, so it’s saturated. The limitation of this specific circuit, therefore, is a maximum input voltage of about 1.3 V. At the other end, anything less than 0.7 V causes the transistor to go into cutoff.
What happens to the base of a transistor when the voltage is positive?
If you apply a positive voltage greater than 0.7 V to the base, the emitter diode will be forward-biased and current will flow from the base, through the emitter and to ground. The collector diode will be reverse-biased, and no current will flow through that diode.
What is the voltage difference between diodes in a transistor?
The transistor turns on slightly harder to deliver the current. and this has produced a voltage difference of 12.7-11.45 = 1.25 volts. Now, these diodes limit increasing the current will lower the output automatically. You see the diodes are helping as the voltage across them does not over 1.2 volts.
What happens at the junction of two anodes in a transistor?
The junction of the two anodes represents the base of a transistor. If you apply a positive voltage greater than 0.7 V to the base, the emitter diode will be forward-biased and current will flow from the base, through the emitter and to ground. The collector diode will be reverse-biased, and no current will flow through that diode.
What kind of transistor to use when IC output is low?
To switch on when the IC output is high use an NPN transistor. To switch on when the IC output is low use a PNP transistor. NPN and PNP transistors are connected differently as shown in the diagrams below but the calculations and properties required are the same for both types of transistor. 2. Find out the supply voltage (s) and load properties.
Why are multiple transistors used in a bipolar transistor?
Sometimes the DC current gain of the bipolar transistor is too low to directly switch the load current or voltage, so multiple switching transistors are used. Here, one small input transistor is used to switch “ON” or “OFF” a much larger current handling output transistor.
Why are transistors still used in simple circuits?
Transistors, for example, typically have much higher operating voltage and power limits in simple circuits than those of comparable ICs. Electronics manufacturers and distributors still make and sell individual transistors because the parts still have some uses.