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Transistor, AC amplification

newuser

Dec 16, 2012
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Hi,

i would like to see the output of this circuit, but i cant start the simulation...am i missing something?

what i tried to start the simulation:
simulation -> time domain

error:
solver returned no data

any ideas whats missing?
 

BobK

Jan 5, 2010
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You have two voltages driving the same net, V2 and V3.

Also the circuit is not very good even if you decoupled with a capacitor. You need two resistors to bias the base, one to ground and one to V+. And you need a capacitor to couple the input so the base is not absolutely driven by the voltage source.

Bob
 

newuser

Dec 16, 2012
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dont i need a dc voltage to bias the transistor and a ac volatge source for my input signal?
EDIT: ive added another resistor for the base and changed the ac input sources node
 
Last edited:

BobK

Jan 5, 2010
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Add a capacitor between the AC source and the base. Otherwise your DC biasing resistors will simply be overridden by the AC voltage.

Bob
 

newuser

Dec 16, 2012
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just realised that i didnt saved my changes from post #5, sry. now they are in.
 

Harald Kapp

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Nov 17, 2011
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Now that should work.
Where's the problem there?
 

newuser

Dec 16, 2012
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im expecting a sinus wave as output, but i only get +15v. have to work some more with the program itself.

what BobK said: why would the AC voltage source override the DC biasing resistors?
isnt the capacitor at the input to block DC voltage coming from the source for the input which might not be a perfect sinus wave power source?
 

BobK

Jan 5, 2010
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The two biasing resistors should be chosen such the the voltage on the collector is 1/2 the supply voltage. With the resistors you have chosen, I expect the transistor to be fully on and stay there, so the output should remain close to 0. The blocking capacitor is fine as you have it.

Bob
 
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