In this tutorial we illustrate a self biased BJT amplifier build on a breadboard and how we can test the amplifier using a soundcard based PC oscilloscope. The bipolar transistor used here is the general purpose 2n3904 transistor. The self biased BJT amplifier design is one of several design method using different biasing method. The following are links to other BJT amplifier design and tested on breadboard with soundcard based PC oscilloscope.
- How to Build BJT amplifier and test with Soundcard based PC Oscilloscope using VDB
- How to build base biased BJT amplifier on breadboard and test with PC soundcard based oscilloscope
The following shows the picture of a self biased BJT amplifier on a breadboard.
The circuit schematic of the above build amplifier is shown below and the resistor and capacitor values were determined in the tutorial How to design Self Biased BJT amplifier.
For different requirement of output voltage and current for self biased amplifier design you can use the online BJT amplifier design calculator.
The PC based oscilloscope used here is the soundcard scope software which you can download freely and use for private and educational use.
https://www.zeitnitz.eu/scms/scope_en?mid=4.01
The software is used to both generate ac signal and acquire and plot the signal on the PC oscilloscope. After the download of the software we can navigate to the signal generation tab to generate a signal which will be available at the PC speaker. The following picture shows the soundcard scope signal generation tab where we generate a sine wave of amplitude of 10mV and frequency of 1KHz.
This sine wave generated is sent through the amplifier and the output is connected to the line in/microphone input of the PC. The following picture shows the 3.5 speaker jack in green where the sine wave comes from the PC is connected to the BJT and the output from amplifier is connected at one end of another 3.5mm male to male green jack and the other end of the jack goes to the PC line in or microphone input.
The following picture shows the input and the amplified signal on the PC oscilloscope.
The following video demonstrates the self bias amplifier designed using 2n3904 transistor on breadboard and the input and amplified signal on the PC oscilloscope.
So in this tutorial we demonstrated how one can build a self biased BJT amplifier on breadboard and test it with free soundcard based PC oscilloscope.
