The amplifier stage on a bipolar transistor allows you to amplify the signal in terms of power or voltage. When the amplification of one stage is not enough, a multi-stage amplifier is built.
Instructions
Step 1
Connect an electrolytic capacitor of about 10 microfarads and a resistor of about 100 ohms in parallel. If an n-p-n transistor is used, connect the minus of the capacitor to the common wire, and if p-n-p, then plus.
Step 2
Connect the emitter of the transistor to the opposite lead of the capacitor. Take a ceramic or paper capacitor with a capacity of about 0.1 microfarad and connect one lead to the base of the transistor. Its opposite pin will be the input for the stage. Now take the second same capacitor and connect one lead to the collector of the transistor. The opposite terminal of this capacitor will be the output for the stage. If you are building not a voltage amplifier, but a power amplifier, do not install a second capacitor at all.
Step 3
Between the power rail and the collector of the transistor, connect a resistor with a resistance of about a kilo-ohm if you are building a voltage amplifier, or a load if you are making a power amplifier.
Step 4
If you are using an n-p-n transistor, apply a positive supply voltage to the stage, and if you are using a p-n-p transistor, apply a negative supply voltage. It should be several volts.
Step 5
Connect a voltmeter between the common wire and the collector of the transistor. It will show the supply voltage. Take a resistor with a resistance of about a megaohm and connect it between the base and the power rail. The voltmeter reading will decrease slightly. Connect resistors of smaller and smaller values until the voltmeter readings are approximately equal to half the supply voltage. De-energize the cascade, then solder the resistor.
Step 6
If you need to gain both voltage and power gain, place the voltage amplifier stage in front of the power amplifier stage. In a multistage amplifier, only the latter can be a power amplification stage. The capacitors between the stages must be leak free.
