Engineers Must Pay

[The New Steve H]

I don't know, man. Engineers always make me think of the Michael Douglas character in "Falling Down."

[diagrammatiks]

just wait till you have to calculate reactance with imaginary numbers and 5 axis transformations.

you'll be wishing for some pure numbers.

or just numbers. any numbers at all.

[VacuumVoodoo]

I don't know, man. Engineers always make me think of the Michael Douglas character in "Falling Down."

You can always switch carrier path and become a programmer, then you won't have to worry whether your numbers are pure or contaminated.

[Zippy]

I don't know, man. Engineers always make me think...

That's a start.

No wonder your head hurts.

[The New Steve H]

The engineers are mad, so I'll tell a physicist joke.

How can you pick out the extroverted physicist in a crowded elevator?

He's the one looking at OTHER PEOPLE'S shoes.

[The New Steve H]

Come on, this is comedy GOLD. Laugh or I'll tell a contour integral joke.

[Colossal]

Come on, this is comedy GOLD. Laugh or I'll tell a contour integral joke.

http://www.youtube.com/watch?v=K8E_zMLCRNg

[The New Steve H]

Tough room.

[The New Steve H]

Okay, I am now angry because these books keep saying resistors ABSORB power. Am I crazy? I always thought they EMITTED power. I mean, a resistor that absorbs power would be cold, right? Like a Peltier cooler or something.

[John_P_WI]

Okay, I am now angry because these books keep saying resistors ABSORB power. Am I crazy?

Resistors convert electrical energy into heat energy. The law of "conservation of energy" where energy is conserved, it is neither created nor destroyed and only changes forms applies here.

I used to develop dynamic braking resistors for locomotives. One of them had a dissipation rating of 5500 kw! You could BBQ on that one! A demonstration of converting momentum (kinetic energy) into electricity and then finally into heat as mentioned above.

As far as your question of being crazy, I am not qualified to answer......

[diagrammatiks]

Okay, I am now angry because these books keep saying resistors ABSORB power. Am I crazy? I always thought they EMITTED power. I mean, a resistor that absorbs power would be cold, right? Like a Peltier cooler or something.

yes they do. they absorb it and give it off as heat.

otherwise how could they resist anything.

[The New Steve H]

It just seems to be a weird way of looking at it. I mean, okay, it's sinking electrical power, but it seems strange to think of something hot as absorbing energy.

Now I'm mad because my other book is equating current with a term which only has units of Kelvins squared. This has to be stopped!

I'm just mad, mad, mad. But for a minute I thought I was going to get to solve a differential equation, which was pretty exciting.

[The New Steve H]

As far as your question of being crazy, I am not qualified to answer......

I appreciate your tact.

I hope no one is taking this thread too seriously. I'm really enjoying this, in spite of all the wrongness I am dealing with. Studying this stuff reminds me of the distant past, when I used to be somewhat intelligent.

[VacuumVoodoo]

A man's got to know his limitations....

[renshen1957]

Okay, I am now angry because these books keep saying resistors ABSORB power. Am I crazy? I always thought they EMITTED power. I mean, a resistor that absorbs power would be cold, right? Like a Peltier cooler or something.

If resistors emitted power they would be called emitters. (smiles) Resistance is the reciprocal of conductance. For example in a circuit the power that is "ABSORBED" (slowed down and emitted as heat) makes possible the lower voltages at different points in the power supply.

Have you read Dave Funk's book on the subject? Funk has chapters on resistors, capacitors, etc, which would be a good foundation and understanding on how a tube amp works before getting wrapped up in theory.

At best, there is a basic understanding but not complete understanding on how a tube works, but being electrical mechanical devices (all the parts in the interior) there is alot of variability.

A 5751 tube should have an amplification factor of 70 as compared to a 12AX7. Yet, I saw a batch of 5751 tubes which had higher gM and amplification (almost a match for the 12AX7) than its brother 5751 tubes.

How a tube works in circuit can cause a lot of variance in amplification, even variance from the same manufacturer and same batch of tubes.

The theory and math is great for caculating an expected result when designing but to quote a famous English Inventor, an ounce of practice (practical application) is worth a ton of theory.

Best Regards,

Steve,

PS The recommendation of additional texts on the subject is a solid one.

A Real life parallel: The first book I read on orchestration by Walter Piston had information, but even for a text book it was poorly written. Rimsky-Korsakov book dealt with orchestral color and styles, which was better. However Cecil Forsythe gave a better explanation (and was incredibly amuzing) on how to write for string technicque, transposing reed instruments, and gave what is now called period (or original) instrument information (and was written about circa 1902). I learned how to write for instruments (technique) with CF, why one would use which instrument with RK and basically used WP as a door stop.

Dave Funk's book gave me the fundametals of how an amp worked, I learned construction techniques from Tino Zottola, however The Ultimate Tone Series of K. O'Conner provided most of the math I used for building amps. The TUT books introduced concepts such as decoupling, galactic grounding, DC stand-off voltage for hum in the filaments.

As to the imaginery numbers and other amp allegra/math check out the tutorials at http://ampbooks.com/home/tutorials/lesson-001

However, knowing how to calculate the value and frequency between a Sovtek Mig 50 amps tonestack value and a Tweed Bassman is all well and good, however do you really need this information when building an amp?

The majority of the Vacuum Tube theory books date to the days of Radio, and later Television which dealt with carrier waves, oscillation, automatic gain control, etc. There would be chapters on audio amplifiers (where Leo Fender got his circuits, originally), but how important is the radio/tv information in building a guitar amp?

Yes, there are uses for math if you want design around a certain power tube (50C5) or an unusual preamp pentode tube. However, what is the likelyhood that you will want to design around an old TV or Radio tube to make an amplifier, especially since those tubes haven't been in production since the early 1980s at best?

Most of the tubes used in guitar amps are those that are available for reasonable amount of money (unless you are into Western Electric Triodes for Hi-Fis or Ham Radio transmitting tubes) in the context of what's in production.

I do not need to know metallurgy, calculus, etc to build a car at a factory. (I would if I was designing a new car's fender) Is you intent to design an amp from the ground up or to understand how it works to build one?