Here i took some random values So please suggest me values for the resistors as well as the for the voltage sources for transistor to act as amplifer

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put on hold as unclear what you're asking by RoyC, Marcus Müller, Elliot Alderson, Blup1980, Warren Hill Jan 13 at 10:46

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  • \$\begingroup\$ Where did you read? \$\endgroup\$ – Sunnyskyguy EE75 Jan 12 at 9:05
  • 3
    \$\begingroup\$ That depends on the transistor, the signal you want to amplify, and how you want it to be amplified. I think you might be missing the very basics of transistors, so it's really not clear how an answer would have to look like to make it "work" for you. So, with a heavy heart: vote to close as "too broad". Also, your question simply seems to be lacking the most important part that you forgot to add; so, a downvote for insufficient diligence is sadly also in order :( \$\endgroup\$ – Marcus Müller Jan 12 at 12:48
  • \$\begingroup\$ I'd start by drawing the schematic and labelling the parts R1, R2 etc. Otherwise this question is unclear and will be closed. \$\endgroup\$ – Warren Hill Jan 13 at 10:46

You need to learn about the voltage-current behaviors of bipolar transistors. Such as this

enter image description here

In that plot, the highest voltage is 12 volts, the highest current is 4+ milliAmps. This circuit will provide that


simulate this circuit – Schematic created using CircuitLab

NOtice the two small circuits to left of the transistor.

The first circuit has just a variable resistor (an potentiometer, or voltage divider) and a 100Kohm resistor to define the current into the base. Use that circuit to measure the I-V plot of your own first transistor (even works for some MOSFETS, but a 2N3904 or 2N2222 are bipolars).

The 2nd circuit is an amplifier, small-signal, self-biasing for a large and relatively low-distortion output voltage swing.

Rout will be that 3Kohm collector resistor, in parallel with the slope of your collector-I-V-lines you get from using the first circuit.

The voltage gain should be 3,000 / (26/2) = 3000 / 13 = 210X.

You'll get lots of distortion, if your input is larger than just a couple milliVolts. (read about linearizing-an-amplifier, for more advanced design).

The input resistance will be that 150Kohm, inparallel with the base resistance in the small-signal model, whichis beta * 1/gm, fo rthis circuit we'll use beta=100 * (26/2) = only 1,300 ohms.

Output bandwidth (speed, frequency response) will be 10 pF and 3K ohms, or 30 nanoSeconds; or about 5MegaHertz, suitable for an untuned AM radio amplifier. Or for audio. Or for video.


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