Impedance Readings

Can someone direct me to an online resource that will outline the electric spectrum? By that, I mean, I understand impedance matching but don't understand what the ranges or symbols mean, ohms, Mv, etc. How many ohms equal a Mv, or whatever. If i don't understand this stuff I don't know if things match or not, even if I know where to look. Help!

Thnx in advance,
Hi Matty

I suggest you look at the sites below. They are the best and shortest I have found online for explaining basic dc and ac electric theory. Your question shows a little confusion. I really doubt if you understand impedance matching if you do not understand Mv and ohms etc. I’ve been wrong before though.

If you want to relate ohms to Mv etc you use ohm's law. They are related
e(voltage)=i(current) times r(resistance). This is for dc current.

For ac (or pulsating dc) capacitance and inductance come into play and the resistance is called impedance. Ohm's law basically holds true for this too but the formulas are slightly different and "phase" comes into play because current and voltage are dancing out of step.

Impedance matching is yet another issue. You’re looking at the effect of the source's resistance on the transfer of voltage, current and issues of efficiency. Like everything else electric circuits need to be impedance (resistance) matched. That is, a circuit likes to be attached to a particular impedance (resistance) in order to work properly. This is easy to understand although it might sound a bit mysterious when you first see it in the context of electricity. A mechanical example might help because they are more everyday for most folks. It is like matching gears on a bike to the ride you are taking. You don’t want to be in 1st gear on a long flat nor in 18th gear going up a hill. You want the right “road resistance” to be in first gear (a BIG hill) and you want much less resistance (down hill with a wind) to make things work in 18th gear for any length of time. Depending on load that the ride presents (can you tell I’m a cyclist?) you are going you need a smaller gear pushing a bigger gear (lots of torque) or a bigger gear pushing a smaller gear (Speed with less torque). Similarly, in electronics, sometimes you want a bigger impedance pushing a smaller impedance and sometimes you want a smaller impedance pushing a bigger one. It depends one what you are trying to do.

Basic rules:
Smaller impedance to bigger impedance: transfers voltage better to next stage
Bigger impedance to smaller impedance: transfers current better to next stage
Equal impedances: most efficient transfer of the both, i.e. “power.” (Power equals Current times voltage)

Impedance is not really an easy topic. You need to at least understand basic dc and ac theory.

Here are two really good online sources for basics. I really don't think you can approach it any other way. It would take a long post even by Sean's standards!(hehe)

Ray Dall, Electronics basics on circuits about as briefly as is possible. About 50 short pages. A helpful overview of tubes begins on page 37.

Randall Aiken, Introductory (Beginner’s) Technical Papers: Nine short papers.

I remain,
Thank you for your lengthy response. I understand the "basic" idea, or concept as to why match components. But you are right, other than that I am "Clueless" :>).

I have to start somewhere so I appreciate the links very much.