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

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srevish

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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.

ckt.JPG
 

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.
 

G4BCH said:
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.
Click to expand...



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.
 

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.
 

G4BCH said:
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.
Click to expand...

Thanks sir, thanks for your help
 

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