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# relationship between input and output voltage of power booster circuit

#### khatus

##### Member level 3
This is a power booster circuit. Here Q1 is a power transistor. I want to determine the relationship between input voltage(Vin) and output voltage (vout) here. and also want to determine Vout.

Please,Some derive me the relation between Vin and vout .How i get the 13.28 volt output from 15 volt input.please show

I have found that,

Here is my simulation. If the input voltage Vin = 15 volt The output voltage is fixed at = 13.28 volt i.e vout = 13.28. The VCC of transistor is 30 volt i.e VCC= 30 volt.the output voltage Vout is independent of transistor collector voltage i,e VCC. And if we increase the VCC from 30 volt to 50 volt the whole increased voltage (50V -30V = 20V) is dropped across VCE of transistor Q1.

Please derive me the relation between Vin and vout. how 15 volt inputs gives 13.28 volt output volatge. Please show me the calculation.

Hi,

there is no calculation, because you operate the OPAMP outside of it´s linear operation range.

And "outside" the range depends on the OPAMP type. We don´t know the OPAMP type.

--> My recommendation: Read the OPAMP´s datasheet and operate the OPAMP within it´s recommended operation range. (input and output wise)

Klaus

Are you trying to build a constant current sink for the load in the
collector of the NPN ?

Clue on analysis, since there is - fdbk, the V at V-
= Vin;

Regards, Dana.