Dumbest Question Ever Asked

[Stomp]

This book is really helping me out atm. 

http://www.amazon.com/Tab-Electronics-Guide-Understanding-Electricity/dp/0071360573

[JKowalski]

OK, as a huge fan of drag racing, I'm going to try and understand this in terms of fuel being injected into an engine via injectors or a supercharger.

The AC signal from a guitar flows into the base of the transistor, correct?  The DC voltage from the 9V battery provides a significant boost to the pressure of the input signal by amplifying (or compressing) the flow of signal (fuel) from the input, correct?  So any unburned fuel (signal) then passes to the emitter (or exhaust).  This is where the analogy kind of falls apart as unburned fuel goes into the atmosphere.  The boosted signal from the base and collector then flows to the output capacitor which removes AC voltage, which then allows the amplified signal to pass to the output of the effect.

Am I sort of on the right track here?

Rick

Not having a strong interest in drag racing, that was confusing to me at first  

It's a start, but they are alot more complex in operation than that. Using analogies is not going to get you far - at some point you have to start using the real terms and actual explainations.

Okay I just tried to start writing out a beginners guide to transistors in this post before i realized how enormous a task that was. These are all the concepts you need to know before you get into transistors, and I dont know how many you know of:

- relationships between current and voltage, by ohms law
- diode operation
- capacitor operation (by the way, capacitors dont stop AC signals, they stop DC signals and pass AC.)
- RC filters

And after you have a firm grasp of how those all work, then we can explain transistor operation to you in terms that will make sense in real life.

I really suggest you do what I said earlier - check out a bunch of electronics books and flip through them until you find an explanation that makes sense to you. Regardless, you have to get through all the passive component concepts before you go anywhere near learning transistors, and as I said, i don't know how many you know.

[Baktown]

I'm kind of like an old barnyard goose that wakes up in a new world every morning, so please bear with me as I ask lots of questions that might be very basic to most people, but which are still abstract to me.  I'm a guitar player first, a drummer second, and a wanna be stompbox builder third.

Rick J

[JKowalski]

I'm kind of like an old barnyard goose that wakes up in a new world every morning, so please bear with me as I ask lots of questions that might be very basic to most people, but which are still abstract to me.  I'm a guitar player first, a drummer second, and a wanna be stompbox builder third.

Rick J

My suggestion still stands. As much as I appreciate and believe in the help and support that all the different people on this forum can give you - I don't think it stands up to the organized, step-by-step, all inclusive teaching of a well written book or well taught class.

This forum is more helpful for specific questions or problems. When you try to learn a whole subject such as electronics with it, you will get alot of misguided, confusing, inconsistent information and methods in an order that does not follow the learning curve. It probably will (and probably has) confused you so far.

Don't get discouraged when you don't get it the first time! You might have to reread the book like 6-7 times, but if that's what it takes, that's what it takes. Always remember - electronics is not just a simple hobby that can be tackled in a couple months. It is a very complex and enormous field of study. Granted, stompboxes aren't the most complex applications of electronics, but that makes them no less difficult. You still have to know what you are doing either way.

[frank_p]

This link had been posted on the forum, maybe it can be of some help.
(I saw it when Wapcat posted it and it was still sitting on my desktop)
http://www.amasci.com/amateur/transis.html



You also have concentrate on the characteristic curve (and first study it in DC biasing condition):







Ref:
http://www.physics.csbsju.edu/trace/CC.html

I₃: The base current is the depth of the 3D graph (curved lines on the 3rd graph). It's the quantity of electrons that are passing by unit time. It's them who are "allowing" the major part of the electron to pass trough the collector and the emitter.
See it as a big valve you can open and close at the top of the dam.  When the base current (I_base) is flowing more, it's like opening the big valve.

V₂: Is V_CE: Is the voltage (or the difference of voltage between the collector and the emitter).  A voltage is a TENSION (like a tension that can be built up in a spring). We call it difference of potential energy (in french).  So it's like water at the top of the fall that is ready to do work (litterally) at the bottom of a dam (in the turbine or the mill).  The turbine is like the load in the biasing circuit of the hydro-electric dam.  It puts resistance (resistor) on the flow and thus, it is transferring energy of a form to an other (the passing water energy in electrical energy: in an hydroelectric powerplant).  To do the same you would put a resistor at the collector to act as the load (converting the energy of the flowing electrons into heat).  You could also put a light bulb instead, and the energy of the flowing electrons would be converted in light (work or energy by unit time  -Watts-   ).

Look at the dotted line of I_C in the drawing below: (you have the 4.5V of tension that is ready to act), the potentiometer at the base of the transistor that is acting like the handle of the big valve (It is using the voltage divider rule).  

Ref:
http://www.mikroe.com/en/books/keu/04.htm

Now:
I₂: in the 3D Graph is I_C (the current that is flowing in the collector of the transistor) and this amount is in approximation, V+ or V_CC or V_Battery divided by the load (R_load or R_C or R_collector).
So:
V_Batt / R_load = I_C

By having the biasing setup you are ready to draw the load line:

You have I_C and V_CC (V_battery  ; V_bb in the graph below )



Ref:
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/loadline.html

In the 3D graph, it would be like a diagonal plane intersecting the 3D characteristic curve.

Plus if you have I_C you are now able to draw the operating point: Q

This is the existant state of the particular transistor that you have put in your biasing circuit.
But since a portion of the charateristic curve is quite linear (or planar) in -the linear region-, you can link easily the base current to the collector current by Beta or h_FE.

In the data sheets of the transistors you'll find that value (h_FE) for a particular transistor.

So you have the basic circuit for amplifying a small signal:



For a particular transistor in the given biasing condition:

I_b = I_C / h_FE
Ref:  http://www.ngsir.netfirms.com/englishhtm/Amplifier.htm

You then have the current in the input loop.
Vin = I_B * R_B + V_BE
And since V_BE is relatively constant for a silicon transistor (= 0.7V), you have all your (basic) DC biasing conditions.

You put a capacitor a the input to block DC and you have your basic amplifier stage:



The headphone is the load as were the light bulb in the DC biasing circuit.

The capacitor have to be there to not influence the biasing structure if an AC wave hit the front end of the circut (The Quiescent point or operating point (Q) must stay as stable as possible).

Forget R₂ (the front end resistors in the link below) for now and go see the animation:
http://www.ngsir.netfirms.com/englishhtm/Amplifier.htm

You'll begin to understand what will be going on when you are going to apply AC at the base of the transistor.

[Sidd]

I think these book-series are very well written. Other books might compress more into each page, but provided you start at the beginning and work yourself through it, I think they should yield a solid understanding of some of these complex subjects. Also, they are free.

http://www.ibiblio.org/kuphaldt/electricCircuits/

[Baktown]

Thanks to everyone for all the good suggestions and references.  Believe it or not, I really want to learn this so I can hopefully give something back to the DIY community (besides bad jokes and smartass comments).

Rick J

[svstee]

Something else you might want to think about is taking an electronics class. I'm in Bakersfield as well, and you might want to check out night classes at Bakersfield College. I'm taking the basic elec one and it has been a huge help to me so far.

[MoltenVoltage]

Simplest distortion, invented by Dave Davies of the Kinks:

The Kinks' third single, "You Really Got Me", hit No. 1 in the United Kingdom and made the top 10 in the United States, boosted by a performance on the U.K. television show Ready Steady Go!. The loud, distorted guitar riff — achieved by Dave's slicing of the speaker cones in his Elpico amplifier (referred to by the band as the "little green amp") — gave the song its signature, gritty guitar sound. "You Really Got Me" arguably provided a blueprint for hard rock, and served as template for heavy metal.

http://en.wikipedia.org/wiki/The_Kinks