mju@mudos.ann-arbor.mi.us (Marc Unangst) (05/12/89)
I mentioned a while back that I had plans for a volume control for the PC.
Since I got quite a few letters asking for me to post it, here it is.
If you have any trouble with it, you can direct inquiries to me at
mju@mudos.ann-arbor.mi.us.
---CUT HERE---cut here---
Materials List
--------------
1 1K-ohm audio-taper panel-mount potentiometer
1 .25" mono headphone jack
1 Four-wire cable (4 feet)
1 External enclosure, with a front panel at least 4 inches wide and 3
inches tall (*)
1 Knob for potentiometer
1 1/4" -> 1/8" headphone adapter (*)
1 1/4" -> Phono plug adapter (*)
(*) denotes optional items. External enclosure is only optional if you
choose to install the control inside the computer.
Wiring Diagram
--------------
+-----------------+
| Potentiometer |
+-----------------+
|(3) |(2) |(1)
| | |
+------+ +--------------> To wire #1
| |
| +---------+
| |
| |
+-+ |
| +--------------> To wire #2
|(3) |(1)
+-----------------+
| Headphone Jack |
+-----------------+
|(2)
+--------------------> To wire #3
Wire #1: Red ("hot") wire removed from speaker
Wire #2: Cold lead on speaker
Wire #3: Hot lead on speaker
Instructions
------------
Solder the connections as shown in the wiring diagram. Here's a list of
leads and wires and where they go:
Potentiometer:
#1: Hot wire removed from speaker
#2: Lead #3 on headphone jack
#3: Lead #1 on headphone jack
Headphone Jack:
#1: Lead #3 on pot and black wire/cold lead on speaker
#2: Hot lead on speaker
#3: Lead #2 on pot
Open up your computer and find the speaker. Identify the hot and cold wires
leading off it. (The cold wire is usually black, and the hot wire is usually
the other one. If in doubt, check it with a voltage meter.) Use a soldering
iron to remove the hot wire from the speaker and attach lead #2 from the
headphone jack to the lug it was attached to. Solder the hot wire (that
you just desoldered) to lead #1 on the pot. Solder lead #1 on the jack
to the cold lead on the speaker (making sure to keep the original black
wire remains attached).
You're done! Check your work for errors, and when you're satisfied, try
booting up your computer and typing "ECHO ^G" (but press Control-G
instead of "^" "G") at the DOS prompt. Play around with the volume
control, to make sure it works right. Now, route the wires out a
vent hole in the computer(**), and close the case. You can now install
the pot and jack in your external case.
(**): Only do this if you're making it in an external enclosure. If you're
keeping it inside the computer, you should drill two holes in the case to put
the pot and jack through.
If you have any questions about this or want to heap praises on the
author, send mail to mju@mudos.ann-arbor.mi.us. Note that this paper
was based on an article called "Turn Down the Sound" (by Wayne Arnett)
in the October, 1987 issue of PC Resource.
--
Marc Unangst
UUCP smart : mju@mudos.ann-arbor.mi.us
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