ubsims@ecsvax.UUCP (William K. Sims) (08/26/87)
LOOKING FOR "HI-FI" AUDIO FROM YOUR PC/XT OR AT? THIS ARTICLE EXPLAINS
MY METHOD OF OBTAINING SUCH......BACH NEVER SOUNDED LIKE THIS!!....
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T1 R1 RCA PLUG
MAKE CONNECTION
ACROSS SPEAKER 3.2 OHM TO 500 OHM ___
MOUNTED IN _________________ ________ |
IBM | )||( \ 200 OHM POT | SLOT COVER
I\ _________| )||( / |
I \ PRI )||( SEC \<---------- |
I /_________ )||( / |__ |
I/ | )||( \ __ (--
SOLDER |_________________ )||(________/___________| | OUTPUT TO
BOTH | MONITOR.
CONNECTIONS MOUNT TRANSFORMER ON |
SIDE OF POWER SUPPLY |
ABOVE THE POWER CONNECTORS.
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AS EVERYONE KNOWS, IBM IS NOT THE BEST FOR AUDIO REPRODUCTION.
I MADE THE CIRCUIT ABOVE, AND WIRED IT UP TO THE SPEAKER THAT EXIST
IN THE IBM. THE TRANSFORMER IS AN OLD 3.2 TO 500 OHM I HAD IN THE
JUNK BOX. ANY SMALL TRANSFORMER(HALF WATT OR SO) WILL DO THE JOB. RADIO
SHACK MAY BE A SOURCE FOR SUCH. THIS CIRCUIT WILL ONLY WORK WITH
MONITORS THAT HAVE AN AUDIO INPUT, SUCH AS THE SEARS TV/MONITOR. ANY
MONITOR THAT HAS RGB AND AUDIO INPUT WILL DO FINE.
WIRING INSTRUCTIONS ---
ATTACH A LENGTH OF TWO CONDUCTOR WIRE FROM THE SPEAKER INSIDE THE IBM.
(I USED TWO LEADS STRIPED FROM SOME RIBBON CABLE, IN THE JUNK BOX
THE LENGTH OF 24 INCHES SHOULD DO IT). CONNECT THE OTHER END TO THE
PRIMARY OF THE TRANSFORMER AS SHOWN (SOLDER). YOU DON'T WANT THESE
CONNECTIONS TO MAKE CONTACT TO ANY GROUND OR ANY PART OF THE COMPUTER.
MAKE SURE THE CONNECTION ON THE PRIMARY SIDE IS COMPLETELY COVERED. NO
BARE WIRE EXPOSED.
THE TRANSFORMER CAN BE MOUNTED ON THE THE SIDE OF THE POWER SUPPLY USING
THE EXISTING SCREWS. I USED A SPARE SLOT OPENING, ON THE REAR OF THE
IBM. REMOVE THE BLANK SLOT COVER, DRILL A HOLE ABOUT CENTER OF COVER
TO FACILITATE MOUNTING A SUB-MINI, OR RCA PHONO TYPE JACK. WHEN THE JACK
IS MOUNTED, REINSTALL THE SLOT COVER INTO POSITION.
MOUNT A 200 OHM POTENTIOMETER ACROSS THE SECONDARY OF THE TRANSFORMER
AS SHOWN ON THE DIAGRAM. CONNECT A LENGTH OF TWO CONDUCTOR WIRE FROM THE
POT(ENTIOMETER), ONE WIRE TO THE WIPER, THE OTHER TO ONE END OF THE POT.
IT DOESN'T MATTER WHICH END. CONNECT THE OTHER END TO THE JACK INSTALLED
ON THE SLOT COVER AND SOLDER. CONNECT A LENGTH OF AUDIO CABLE FROM THE
PLUG YOU INSTALLED TO THE AUDIO INPUT ON THE REAR OF YOUR MONITOR. IBM
MONITORS CAN NOT BE USED. THEY DO NOT HAVE ANY AUDIO INPUT ELECTRONICS.
ADJUST THE VOLUME CONTROL ON THE MONITOR FOR ABOUT HALF. NOW LOAD
IN SOME PC-MUSIC, OR SOMETHING THAT HAS AUDIO, SUCH AS A GAME. ADJUST
THE 200 OHM POT ON THE TRANSFORMER FOR A COMFORTABLE LEVEL. ADJUST FOR
BEST QUALITY AUDIO. REPLACE THE CASE, AND ENJOY IBM "HI-FI".
THERE YOU HAVE IT, A GOOD SOUNDING IBM AUDIO...WHAT!!!!!, I KNOW I HAVE
A ENGINE ON MY AIRPLANE NOW, I CAN HEAR IT!!!!! (FS). HUMmmmmmmmmmm...
THERE IS ONE EXCEPTION, I SAID, THIS WOULD NOT WORK WITH IBM MONITORS,
AND ONLY WORK WITH MONITORS, THAT HAVE A INPUT FOR AUDIO. THAT IS
NOT ALL TOGETHER TRUE. IT IS TRUE, IT WILL NOT WORK WITH IBM MONITORS
BUT YOU CAN USE ONE OF THESE SMALL SPEAKER AMPLIFIER SUCH AS RADIO SHACK
SELLS FOR AROUND 3 TO 15 DOLLARS..
ANY QUESTIONS CAN BE SEND VIA E-MAIL TO UBSIMS@ECSVAX OR
UBSIMS@UNC.BITNET...GOOD LUCK AND HAVE FUN!!!