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I am a beguiner in electronics and need to learn how to bias a transistor to make a basic amplifier ?
How to calculate the resistors ?
Let's say I have an BC547 NPN transistor and i want to bias it in common emmiter mode what should i take into consideration (the load ...) ?
please help .
To design your circuit you will need information from a datasheet on your transistor. Some important things to know are Vceo and Ic max. The Vceo lets you know the maximum voltage you can use across the collector/emitter terminals. This basically would help you select a Vcc voltage to use. You cannot use a Vcc that exceeds the Vceo and you cannot use Ic that exceeds the Ic max.
Now it would be good to see characteristic curves for this BC547 transistor. See attached file. Having this information you can develop a load line from the cutoff point to the saturation point, and then select an operating point on the load line near the middle.
From here you can start to develop your circuit using whatever bias method you choose. You can select from self bias, collector feedback bias or voltage divider bias. They each have their pros and cons but voltage divider bias, I think, has the most flexibility. This should give you a good start.