Homebrew PCBs

Ah, that explains a lot.

I've been only dealing with DC circuits until now.  I have yet to play with
audio or AC, I've only been playing with micro-processors and supporting
components.

Robert
:)



> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com 
> [mailto:Homebrew_PCBs@yahoogroups.com] De la part de Henrik Olsson
> Envoyé : avril 26 2006 13:13
> À : Homebrew_PCBs@yahoogroups.com
> Objet : Re: [Homebrew_PCBs] Re: Some toner transfer experiments
> 
> 
> 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.
>