how to calculate the collector current Ic and power dissipation of PNP transistor

[srevish]

Hi all,

Can any one help me to find the collector current Ic & power dissipation of the PNP transistor Q3 given in my circuit.

Kindly give me your feedback & your guidance , it will be very helpful for me.

 

[G4BCH]

When Q1 is turned on the base current, Ib in Q3 is (24-Vbe)/2k, dissiapation Ib * Vbe
the collector circuit will be in saturation ( work it ou tfor your self)
The collector current will be (24 -Vsat -10V)/120, dissiapation Ic * Vsat
Total dissiaption the sum of both collector and base circuit dissiaption.
Making a few simplifying assumptions it will be of the order of 50mW.

 

[srevish]

When Q1 is turned on the base current, Ib in Q3 is (24-Vbe)/2k, dissiapation Ib * Vbe
the collector circuit will be in saturation ( work it ou tfor your self)
The collector current will be (24 -Vsat -10V)/120, dissiapation Ic * Vsat
Total dissiaption the sum of both collector and base circuit dissiaption.
Making a few simplifying assumptions it will be of the order of 50mW.

Dear Sir,

Thanks for your help, I am quite new to this, Can you please tell me how to clacutate Vbe and Vsat. This will be great help to me.

 

[G4BCH]

You have to look them up on the transistor data sheet.
They vary a bit with current and device type, for the devices you are using vbe = 0.7 and Vsat = 0.3 wshould be about right.

 

[srevish]

You have to look them up on the transistor data sheet.
They vary a bit with current and device type, for the devices you are using vbe = 0.7 and Vsat = 0.3 wshould be about right.

Thanks sir, thanks for your help