Transistors

Thread Starter

anditechnovire

Joined Dec 24, 2019
24
Why is the input mode different in some" common collector "mode of a transistor circuit diagram? Some are between the emitter-base while others are between the collector- base. Will they not have different effects?
 

Papabravo

Joined Feb 24, 2006
12,767
There are three configurations of the transistor and they each have different properties. They are referred to by the names:
  1. Common Emitter
  2. Common Base
  3. Common Collector, aka Emitter Follower
These names and the circuits they represent were derived from similar circuits and names from the vacuum tube era. They were:
  1. Common Cathode
  2. Common Grid
  3. Common Plate aka Cathode Follower
 

Thread Starter

anditechnovire

Joined Dec 24, 2019
24
No.
I don't know what "between the collector-base" means.
Ok I mean that in some diagram s of an emitter follower(CC mode), the input voltage is applied in between the collector and base junction, while in other schematic, it's applied inbetween emitter and base
 

Papabravo

Joined Feb 24, 2006
12,767
Ok. I mean that in some diagrams of an emitter follower(CC mode), the input voltage is applied in between the collector and base junction, while in other schematic, it's applied in between emitter and base N.B. this would be a common emitter configuration.
That is because different circuits do different things. It would help greatly if you showed us a picture of what you are talking about. Words just do not suffice.
 

dl324

Joined Mar 30, 2015
9,577
Ok I mean that in some diagram s of an emitter follower(CC mode), the input voltage is applied in between the collector and base junction, while in other schematic, it's applied inbetween emitter and base
We need to see a schematic. It's possible to operate a transistor in inverted mode, but you have a very low beta.
 
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Bordodynov

Joined May 20, 2015
2,469
What do you say to my example of two circuitry? The upper one is a circuit with a common collector, and the lower one is a circuit with a common emitter. I counted the voltage swings on the output resistor.:)
 

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Thread Starter

anditechnovire

Joined Dec 24, 2019
24
Welcome to AAC!

It would be helpful if you posted circuits so we can see what you're talking about.
We need to see a schematic. It's possible to operate a transistor in inverted mode, but you have a very low beta.
We need to see a schematic. It's possible to operate a transistor in inverted mode, but you have a very low beta.

Welcome to AAC!

It would be helpful if you posted circuits so we can see what you're talking about.
9
Like to see that.

ak
 

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Wolframore

Joined Jan 21, 2019
1,530
Actually I ran the simulation its interesting. fig 2 is better than fig 1... there less drop on the base resistor increasing base current about 100x more and causing the transistor to saturate. It’s unusual and not normally done this way but I like it.

note simple sim performed using same transistor, all resistors as 1k and same voltage sources. But theres A huge difference between the two which is. 1st one has one voltage source and second has 2 separate sources. Edit using 1v sources when I raise the voltages it just gets about double current you have to lower load to see it. Makes sense with double voltage but very interesting when it’s 1v sources... greater delta due to ratio of Vfd to bias voltage.
 
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