Re: volume control adapter?

[Rubywand <rubywand@swbell.net>]

Simon Biber writes ...
> 
> When turned all the way up you have a large resistance from the control in
> parallel with the speaker. Since the speaker is only 8 ohms this won't make
> a big difference. When turned down all the way you have no current through
> the speaker, and all going through the backplane of the control. It's hardly
> shorting it out, a 1k resistor will pass 5 milliamps.
> 
 ....

     The circuit would be okay on a IIgs where one of the Speaker leads does go
to a ground. 1000 Ohms is kind of high, though. With such a small load R (8
Ohms for the Speaker) you are not getting much 'divider' action. Mainly, you
have a series R and a fairly small range over which turning the knob will make
any noticeble difference. A max control R of around 25 Ohms would be better.

     The circuit would not work on many Apple II's-- like the II+ and IIe.
These place the Speaker between +5V and an output transistor. Swapping in a
connection to GND would eliminate the power source to the output transistor and
you would not get any sound at all.



Rubywand