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Analogy about Transistor

A

Animesh Maurya

Jan 1, 1970
0
I have developed an analogy about transistor's amplification action.

Consider an PNP transistor in Common-Base configuration.
Emitter-Base region is forward biased and that of Collector-Base
region is reverse biased.

______________________
| | | |
-------| P | N | P |-------
| | | | | |
| _________ __________ |
| | |
|+ =======>> | - |
----- | ---
--- | -----
|- | +|
| | <<======== |
| | |
------------------------------------


Now replace the transistor with a hollow cylindrical container.

Place two porous membranes vertically opposite to each other at the
centre of the cylinder and call the enclosed region as base.

Distance between these two membranes is considered small as compared
to the length of the cylinder due to the fact that base region is
small in a transistor.

A small hole in made on the body of the cylinder in the base region.
Diameter of this hole is small than that of emitter & collector.

Connect this assembly using tubes in Common-Base configuration and put
pumps in place of a battery.
Fill up the tubes with water. Assume that water flows in the same
direction as that of the conventional current of battery (i.e. form
+ve to –ve).

Now put on the pumps and see what happens.

Let us first highlight the Emitter-Base region.

Water flowing form the emitter reaches the base and will start
dividing. But majority of water will be transferred to the collector,
as the base opening in very small.

Moreover in Collector-Base region the pump is applying force which is
just opposite to that of the base and thus making base current less
and less, which in turns facilitates large collector current. This
causes amplification.

Analogies are seldom perfect and at times can be misleading. I don't
know to which extent it is correct.

Also one major drawback in that I cant explain amplification in case
of a NPN transistor, if the above assumption are unaltered.

Thanks

Animesh Maurya
 
D

Dana Raymond

Jan 1, 1970
0
I heard somewhere that "Transistor" comes from Transference of Resistance.
Just a datapoint.

Animesh said:
I have developed an analogy about transistor's amplification action.

Consider an PNP transistor in Common-Base configuration.
Emitter-Base region is forward biased and that of Collector-Base
region is reverse biased.

______________________
| | | |
-------| P | N | P |-------
| | | | | |
| _________ __________ |
| | |
|+ =======>> | - |
----- | ---
--- | -----
|- | +|
| | <<======== |
| | |
------------------------------------

Now replace the transistor with a hollow cylindrical container.

Place two porous membranes vertically opposite to each other at the
centre of the cylinder and call the enclosed region as base.

Distance between these two membranes is considered small as compared
to the length of the cylinder due to the fact that base region is
small in a transistor.

A small hole in made on the body of the cylinder in the base region.
Diameter of this hole is small than that of emitter & collector.

Connect this assembly using tubes in Common-Base configuration and put
pumps in place of a battery.
Fill up the tubes with water. Assume that water flows in the same
direction as that of the conventional current of battery (i.e. form
+ve to -ve).

Now put on the pumps and see what happens.

Let us first highlight the Emitter-Base region.

Water flowing form the emitter reaches the base and will start
dividing. But majority of water will be transferred to the collector,
as the base opening in very small.

Moreover in Collector-Base region the pump is applying force which is
just opposite to that of the base and thus making base current less
and less, which in turns facilitates large collector current. This
causes amplification.

Analogies are seldom perfect and at times can be misleading. I don't
know to which extent it is correct.

Also one major drawback in that I cant explain amplification in case
of a NPN transistor, if the above assumption are unaltered.

Thanks

Animesh Maurya

It seems to me that you could replace the transistor with a pair of
resistors (one from emitter to base, and one from base to collector),
and the same analogy would apply just as well. Your model needs more
details before it explains anything. Charge carriers act very
differently in a chunk of semiconductor with little electric field
through it than they do in a chunk containing a large electric field.
Think about which volumes are emptied of almost all charge carriers
and biased with an electric field, and which volumes are flooded with
charge carriers but have little electric field.
 
D

DJ Bartlett

Jan 1, 1970
0
It's an amalgam of transducer and resistor

just a datapoint 8 D.

DJ
 
D

Dana Raymond

Jan 1, 1970
0
Thats surprising since there is no aspect of a transistor that could be
considered a transducer.

DJ Bartlett said:
It's an amalgam of transducer and resistor

just a datapoint 8 D.

DJ
 
Z

zigoteau

Jan 1, 1970
0
[email protected] (Animesh Maurya) wrote in message
Hi Animesh,
I have developed an analogy about transistor's amplification action.

Consider an PNP transistor in Common-Base configuration.
Emitter-Base region is forward biased and that of Collector-Base
region is reverse biased.

Now replace the transistor with a hollow cylindrical container.
I'm afraid your analogy is not very good and does not explain or
reproduce any of the characteristic features of a transistor. How does
it explain the rectification of the emitter-base junction and the
base-collector junction? These depend intrinsically on the fact that a
semiconductor has majority and minority carriers, aspects which a
hydraulic model is totally incapable of mimicking.

Cheers,

Zigoteau.
 
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