- #1
Effect of load voltage variation in this circuit
In summary, the circuit from Horowitz and Hill has a negative feedback mechanism that helps to reduce the effects of changes in load voltage. As load current increases, Q1 is turned on harder, causing a decrease in the collector current of Q2 and ultimately maintaining a consistent load current. The same process happens in reverse when load current decreases. This negative feedback helps to eliminate the early effect in the circuit.
- #2
berkeman
Mentor
- 67,058
- 19,876
brainbaby said:
Hey, that circuit is from Horowitz and Hill
The collector current of Q2 is mostly set by the current through R2, which is set by its resistance and the voltage across it (which is being held at about a diode drop by the E-B junction of Q1. As long as the load voltage doesn't get big enough to take Q2 out of the active region, the load current should be pretty independent of the load voltage.
- #3
Jony130
- 627
- 138
Forget about early effect in this circuit. this circuit has a negative feedback mechanism which reduce the early effect.
As load current tries to increase his value, the voltage drop across R2 and VbeQ1 also increases. This turns-ON Q1 harder (Ic1 current increase ), larger Ic1 current increase voltage drop across R1 resistor this reduces the Vb2 voltage and Vbe2 in the same time, thereby reducing the collector current of Q2 and load current.
As you can see negative feedback restore the previous value of a load current.
The same things happens when load current tries to decreases. In this case Vbe1 is dropping which reduces Ic1 collector current, this make less voltage drop across R1.
So Vbe2 must increase his value and in result bring back the previous value of a load current.
As load current tries to increase his value, the voltage drop across R2 and VbeQ1 also increases. This turns-ON Q1 harder (Ic1 current increase ), larger Ic1 current increase voltage drop across R1 resistor this reduces the Vb2 voltage and Vbe2 in the same time, thereby reducing the collector current of Q2 and load current.
As you can see negative feedback restore the previous value of a load current.
The same things happens when load current tries to decreases. In this case Vbe1 is dropping which reduces Ic1 collector current, this make less voltage drop across R1.
So Vbe2 must increase his value and in result bring back the previous value of a load current.
- #4
brainbaby
- 228
- 5
thanks buddy i got it...great jobJony130 said:
1. What is the effect of increasing load voltage in this circuit?
Increasing the load voltage in a circuit can cause an increase in current flow, which can lead to higher power dissipation and potential damage to components. It can also cause a decrease in circuit efficiency and a shorter lifespan of the circuit.
2. How does load voltage variation affect the circuit's performance?
Load voltage variation can result in fluctuations in the output voltage and current of the circuit, leading to instability and potential circuit failure. It can also affect the accuracy and precision of the circuit's operation.
3. Can a higher load voltage damage the circuit?
Yes, a higher load voltage can cause excessive stress on components and lead to their failure. It can also cause overheating and damage to sensitive electronic components.
4. What precautions should be taken when dealing with load voltage in a circuit?
It is important to carefully select and regulate the load voltage in a circuit to ensure it does not exceed the maximum ratings of components. Adequate heat dissipation and protection measures should also be implemented to prevent damage to the circuit.
5. How do you determine the optimal load voltage for a circuit?
The optimal load voltage for a circuit can be determined by considering the specifications and ratings of the components used in the circuit. It is important to choose a load voltage that will provide the desired output without causing stress or damage to the circuit.
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