Maker Pro
Maker Pro

Transistor, AC amplification

newuser

Dec 16, 2012
9
Joined
Dec 16, 2012
Messages
9
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
7,682
Joined
Jan 5, 2010
Messages
7,682
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
9
Joined
Dec 16, 2012
Messages
9
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
7,682
Joined
Jan 5, 2010
Messages
7,682
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
9
Joined
Dec 16, 2012
Messages
9
just realised that i didnt saved my changes from post #5, sry. now they are in.
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,700
Joined
Nov 17, 2011
Messages
13,700
Now that should work.
Where's the problem there?
 

newuser

Dec 16, 2012
9
Joined
Dec 16, 2012
Messages
9
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
7,682
Joined
Jan 5, 2010
Messages
7,682
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
 
Top