Re: IIe sound output

[mjmahon@aol.com (Michael J. Mahon)]

Michael Black wrote:

>Simon Williams (DONTemail@luddite.ca) writes:
>> Anyone tinkered with replacing the IIe's crappy speaker with a line out?
>> I'm a little hesitant to connect the wires up to my stereo without first
>> hearing from someone who's already been electrocuted =8-O
>> 
>> SW
>
>Unless the IIe changed it's circuitry from the II, it's not going to
>be just a matter of running a cable.
>
>I haven't looked at the II schematic in a while, but memory tells me
>the internal speaker is connected between the +5v line and the collector
>of a transistor.  You don't want to run that +5v line to your stereo.
>And if the speaker is not there, that transistor will not be able to
>operate.
>
>You need to take the collector side of the speaker and connect that to
>the input of your stereo, using a capacitor to ensure that the DC voltage
>doesn't get into the stereo.  And then connect the ground of the Apple to
>the ground of the stereo.  And unless you are willing to leave the speaker
>in the IIe, you're going to have to put some resistor, maybe 100 ohms or
>so, between the collector of the transistor and the +5v line, ie between
>the two points that the speaker is connected to now.
>
>I suspect some have done this, and can provide specific values, but I
>thought it was important to warn you against just running the wires 
>to your stereo.

This is a good approach.

Another is to put a small audio transformer (like the kind found on
any modem card) to AC couple the Apple output to a line output.

I used this approach to couple the speaker jack of the Apple main
board to a 100 ohm volume control and then to the speaker.  I also
inserted a phone jack in the speaker circuit, so that when headphones
or a "line out" plug is inserted, the speaker is muted.

-michael

Check out 8-bit Apple sound that will amaze you on my
Home page:  http://members.aol.com/MJMahon/