Effect of change in capacitance value.

[Gjnitp]

hi,
could anybody help me out with this problem?
what happens when the value of bypass capacitance and coupling capacitance in an amplifier changes?What is its effect on reducing the voltage drop across the emitter resistance(bypass capacitor) and effect on blocking the dc signals(coupling capaictor)?

[reachrkata]

1) By pass capacitors are used to prevent any voltage spikes that could falsely turn on the transistor. Effect of capacitance value is that of a low pass filter - higher the capacitance, lower is the frequency of spike which the cap can bypass. Eg- if a 1uF cap by passes all frequencies greater than 1khz, a 10uF cap would pass all frequencies greater than 100hz also.

2) Effect of coupling capacitance value is that of a high pass filter - higher the capacitance, more are the low frequency signals which the capacitor will prevent. Eg- if a 1uF cap passes all frequencies greater than 1khz, a 10uF cap would pass all frequencies greater than 10khz only.

Karthik

[Gjnitp]

thankyou karthik for the reply....

[sauravgoswami]

Hi freinds,karthik has given a nice reply,let make it more simple,also decide by-pass capacitors the gain of the amplifier,and coupling capacitor decide the frequency range of the amplifier.

[sauravgoswami]

Well i have gone through your post,you can get projects on micrcontrollers anywere,I have some ideas which have never been implemented.