Homebrew PCBs

Robert,
Depending a bit on what you are doing they may be "the same" - or not.
Impedance is sort of resistance but it varies depending on the frequency of 
the current passing thru it.

For example, take your average speaker, it will probably have a label on it 
saying Impedance 4-8ohm but if you take your meter and measure the 
resistance of the coil it will be near zero ohm.

A high power amp can easliy destroy a speaker if the output is offset from 
0V. That's why audio amplifiers have a protection circuit on the output that 
disconects the speaker if there's any DC-component at the output. Before 
push-pull circuits made it's way into the amps they used to have a big 
capcitor in series with the output to make the output centered around 0V 
instead of 50% of the powersupply voltage.

See, there you go, that cap has a VERY high resistance (DC) but it still 
passes current from the amp to the speaker (AC).

HTH

    /Henrik Olsson.


----- Original Message ----- 
From: "Robert Hedan" <robert.hedan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, April 26, 2006 6:32 PM
Subject: [Homebrew_PCBs] Re: Some toner transfer experiments


Impedance is the same as resistance?

Crap, you've just made things so much clearer for me now.  Seriously, I had
yet seen a place that said they were one and the same.  Ok, I don't look
that deeply, but still.  I had learned what resistance was (along with
voltage and current), and then I kept seeing references to impedance here
and there, never picking up exactly what it meant.

Robert
:D