Novice Asks Question about Transistors

[telstarmagikistferrari]

hey all, thanks for tolerating my posts in this forum.
i'm writing out of confusion about just what transistors do, what the different kinds are, what are the applications of these types are with synths?

All the (admittedly geared toward noobs) texts I've read sort of gloss over the purpose / applications of transistors.

I'm gonna go read some stuff elsewhere, see what turns up. Thanks for any info. I enjoy reading past threads and stuff here - very informative.

[telstarmagikistferrari]

Ok, so I found out some basic info on Wikipedia. This included:

"An electrical signal can be amplified by using a device [transistor being one of these] that allows a small current or voltage to control the flow of a much larger current. "

Not only control but amplification of the voltage/signal, correct?

[ark]

Asking what transistors do in circuits is a little like asking what verbs do in prose. In both cases, it's hard to see how to answer the question in a way that would make any sense unless the listener already knows enough to make the question unnecessary.

[telstarmagikistferrari]

OK, a few more totally basic inquiries.

I understand a bit about how resistors and capacitors work, not much. Part of my problem is that, despite some reading about carriers, electrons and the such, I don't have a 'visceral' understanding of how current flows. From what I understand, it comes FROM the negative - side of a battery (or other power) thru to the positive. is this info applicable when looking at a schematic. ie does one 'start' at - and go from there?

Here's some stuff I found that seems to help re: capacitors:

Regarding passing AC signals:

"The amplitude is scaled by the product of capacitance and angular frequency, and a 90 degree (quarter cycle) phase shift. Capacitors effectively conduct AC, as the current maintains a constant, nonzero amplitude. This occurs despite charge never passing directly through the dielectric."

I know they prevent or cause something , but what exactly. Fiddling with cap and resistor values while building a triple 555 optotheremin suggested to me that the capacitor affected the possible range of the timers. But how? and from which direction? Do they alter the voltage/current ratio?

How is this different from a resistor? I struggle to understand the 'language' involved with resistance. Do they decrease the voltage or the current? Or do they Slow It Down?

I know it may seem stupid to be struggling with this level stuff, and i've had to humble myself to post it. It may be helpful for others to refer to (if anyone ever answers!) I feel that some help in this thread would be incredibly helpful. Thanks all.

[telstarmagikistferrari]

I was afraid of that! Thanks anyway, I'll keep studying

[bugfight]

run to a half priced books or likesuchas and get this book:
Getting Started in Electronics -- by Forrest M. Mims III

[Uncle Krunkus]

Firstly, that capacitor description is way too deep for a beginner.

Second, a resistor inhibits current. Current is "pushed" by voltage. So, 1Volt across a 1Ohm resistor pushes 1Amp of current. 2Volts across the 1Ohm resistor would push 2Amps. 1Volt across a 2Ohm resistor would push 1/2 an Amp.

V=I*R
I=V/R
R=V/I

Third, a transistor is like a voltage controlled resistor. In it's simplist form it acts as a voltage controlled switch.

There's a lot more, but I'm going to watch something on the telly, be back later.

[telstarmagikistferrari]

I've made loads of progress since my last post, I got an excellent book from the library that's going into considerably greater depth than some of the other sources I was reading. Thanks for your help, Krunkus. Believe it or not I'm a fairly bright guy, I just never had any background in electronics (being 27 I started w computers at 14); never did any with my dad or anything at all. So it's all a bit foreign, (and exciting, and demystifying, and mystifying..)..

[Uncle Krunkus]

Oh I believe you're a bright guy.
You're able to ask questions about things which you're not sure about. That's about as bright as you can get in my book!
If you have a bit of a search around here, you'll see that I'm still asking plenty of questions, and learning heaps all the time. It's one of the things I like about hanging out here. Everyone is very generous with their knowledge and experience. And what goes around comes around. It's really what the net is all about as far as I'm concerned. We all have certain parts of the jigsaw, and together we can work as a real community.