# How do I make sense of a Transistor DataSheet.

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#### Zanderist

##### Member level 3
In this pdf for the 2N3904

https://www.fairchildsemi.com/ds/2N/2N3904.pdf

What part of this data sheet should I be looking at to figure out what my bias should be?

I want to experiment with my signal generator, so I can see the transistor in action.

Every other time I have tried this I get annoying peaks(clipping) that do not reflect the signal coming in at the base.

Also what is the procedure to make a graph like this?

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#### KJ6EAD

##### Advanced Member level 3
The graph you're displaying is a transistor load line. You need to research "operating point", "load line" and "characteristic curve" related to transistors. There's plenty of information online.

Zanderist

### Zanderist

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#### bigdogguru

##### Administrator
Here's a fairly good tutorial online covering the terms KJ6EAD mentioned, including characteristic curve, operating point. The tutorial is 8 pages long and begin to cover the characteristic curve on page 2.

Electronics Tutorial - Bipolar Junction Transistors

Hope it gets you started in the right direction.

Zanderist

### Zanderist

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#### Zanderist

##### Member level 3
Thanks guys, I've been looking on youtube before this thread about transistor biasing and found videos put out by the Indian Institutes of Technology and Indian Institute of Science.

It was this hour long video that I saw the graph and became interested in making such a graph;

YouTube - ‪Lecture - 11 Transistor Biasing‬‏

#### Miguel Gaspar

##### Advanced Member level 1
The information that the graphics gives you:
Voltage of the source≈ 17.8V
the collector resistance ≈17.8V/37mA = 481Ω
β ≈ 14mA/50µA = 280
R1 = ?
R2 = ?

For these two values you will need the Ic vs Vbe, in order to obtain the Vbe that will produce the IC.

Zanderist

### Zanderist

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#### potdarsagar

##### Newbie level 6
Bro clipping may be due to voltage exceeding its Vsat.

Zanderist

### Zanderist

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#### Zanderist

##### Member level 3
Bro clipping may be due to voltage exceeding its Vsat.

This holds some truth because I've been playing with transistors blindly, meaning I was just going off gut feelings and not using the multimeters in order to have understand what was happening. however, the voltage I was using was a mere 5 volts with a max 500mA supply, and this transistor's max voltage is around 40 volts. ( I'm assume then that it was the current causing the clipping)

Now for a little of the 'behind the scenes of this thread' ;

My intentions where to make a push-pull amplifier without a PnP, I noticed in a simulator that if I used a zener diode connected in the direction of emitter to base (the bar of diode facing base) that I could do it.

Although I noticed with a darling pair configuration the current was compounded and I was able to produce a carrier signal (from a nice function generator I got as a gift) which was picked up on my small Am/Fm radio, the only problem was that if I tried using a mic to transmit my voice it would come out sounding like it was extremely distorted- (despite it's close proximity to the breadboard circuit)- I sounded like a robot.

All I knew was that a transistor was making the current at Ic equal to Ib x hfe. From this I figured that this extra current would be enough to generate a magnetic field within a speaker.

Another thing I had happening- (not totally related to the above story) -to me was that the transistors were heating up, now I don't know if this will make them permanently damaged since it didn't get to the point that the transistor was smoking. I wasn't particular worried because I could just go out to radio shack and pick up another pack of 15 transistors for \$1.94 USD ( or in other words the price of a 20oz coke that's heavily taxed).

These are the events leading up to this thread.

Senthilkumar_rjpm

### Senthilkumar_rjpm

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