Signal Amplification BC547

Other Hardware General Electronics
1

Hi,

I am trying to amplify a 5 V 60 Hz square wave using a BC547a. The circuit I have hooked up is +12 V at the collector, 5 V square wave at the base. It is my understanding that this will produce a 12 V square wave at the emitter of the transistor. Is this correct?

Thanks,
Ed

2

JohnLincoln:
The collector will now switch from 0V to +12V.

Be aware this inverts the square wave, though that is usually no problem, it depends on exactly what you are trying to do with that signal in that part of your circuit.

3

Oh ok, so I need to configure it as a common emitter amplifier.

Thanks

4

Do you mean amplify or level-convert?

Amplify is a linear operation where the output amplitude has a constant
relationship to the input signal.

Level convert takes a logic signal (two states) and boosts the voltage to
a different one - the output voltages are fixed and do not depend on the
input voltages, although an insufficient input will fail to generate correct
outputs.

For amplification a common-emitter circuit with shunt-feedback via
an emitter resistor is commonly used.

For level shifting a common-emitter switching circuit is used which
has no emitter resistor and requires a base-resistor to protect the transistor
from damage.

5

I am trying to level convert, by your description. So either way the my new signal comes from the collector and not the emitter, correct?