The simplest triode audio amplifier circuit adjusts the size of R1 so that the signal is not distorted at maximum output, and R can output more power.
If you have a multimeter, you can adjust the C pole voltage to about 1/2 of the power supply voltage. 
Figure 1. Fixed bias, power supply voltage has a great influence on the bias current. Basic common emitter circuit 
In Figure 2, the bias is connected to the negative feedback, the amplification becomes smaller, and the power supply voltage has less influence on the bias current.
Voltage negative feedback connection, adapt to a wider voltage range.
This class of class A amplification has the lowest efficiency and is characterized by simplicity. It is rarely used in low-voltage circuits because the output power is too small, and it is actually used in power-driven circuits while amplifying voltage and current.
KNBL1-32 Residual Current Circuit Breaker With Over Load Protection
KNBL1-32 TWO FUNCTION : MCB AND RCCB FUNCTIONS
leakage breaker is suitable for the leakage protection of the line of AC 50/60Hz, rated voltage single phase 240V, rated current up to 63A. When there is human electricity shock or if the leakage current of the line exceeds the prescribed value, it will automatically cut off the power within 0.1s to protect human safety and prevent the accident due to the current leakage.
leakage breaker can protect against overload and short-circuit. It can be used to protect the line from being overloaded and short-circuited as wellas infrequent changeover of the line in normal situation. It complies with standard of IEC/EN61009-1 and GB16917.1.
KNBL1-32 Residual Current Circuit Breaker,Residual Current Circuit Breaker with Over Load Protection 1p,Residual Current Circuit Breaker with Over Load Protection 2p
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