Odd parts
--------
Someone mentioned old fashioned Knife switches.You can buy them
at American Science and Surplus (sciplus.com) for $2.25
The catalog is a collection of many unusual parts for hobbyists.
They have a Telegraph key for $ 3.50.
 
Audio cassettes
---------------
When I hear a cassette where the sound is going up and down,
I know that it had been damaged by a magnetic field.Then
I ran into a cassete where the sound volume was stable but it
sounded like a foreign language.After some tests,I found
that there were two twists in the tape and the sound was 
feom the second track ,between the twists,running backwards.
I used a winding tool that was an electric screwdriver with a 
Phillips bit jammed into a black,plastic hub from a discarded 
cassette assembly.It took a while to find the 2 twists.
I got them out by pulling the tape across a hot,25 Watt light
bulb.
 
Test Scratches on CD/DVD
-----------------------------
 As a hobby,I try to repair audio and video tapes for our 
Claymont,DE library.But everything is going to CDs and DVDs.For 
questionablle disks,I would clean it first.I would take a 
tissue,cut it in half,fold it into a pad of about 2" ,soak it 
with 91% rubbing alcohol and rub hard on the disk bottom going 
from center to edge.The scratches were still there.I bought a 
Memorex "Optifix PRO ($35.00)" with a pad for polishing with Al 
Oxide powder in a liquid.In some cases his helped;others were 
still uncertain.
The only way I can test a CD is to play it and look 
for failures.But I don't want to spend an hour listening to 
something that I'm not interested in.I don't have and don't 
intend to get a DVD player.I'm not going to sit for 2 hours 
for some of the dumb movies now available.Especially now with 
the new standards ( Blue Ray) coming along.
 
Norton Utilities  (DOS-1985 ) had DT.COM to test floppies so I 
tried it in my HP with Pentium 2  XP ,a CD writer as drive F
and DVD drive.
I would go to DOS (command prompt),type in  DT F: /f>savdir 
where savdir showed the result of test.I put in a a good music 
CD and DT showed no errors.I checked savdir with a text editor 
and got:File Tracko1.CDA  to file track11.CDA  then a string of 
about 24 hilighted dash characters,then"No errors reading files".
 
I had collected some free AOL disks for experiments and tried one.
To keep AOL from autoplay,I shut off autoplay by :Right click 
My Computer,Right click on drive F,go to properties,Select action,
chose take NO action.It didn't work.I had to EXIT from several 
AOL menus anyway .It put an AOL Icon on my screen that prevented
me from using my modem "Modem in Use".Had to delete the shortcut,
then Power OFF and ON to clear the modem software.
 
I tried onee AOL disk using  DT F: /f>savdir.It started
reading the disk,the CD light blinking ,and after 3 3/4  minutes 
it finished with NO errors.SAVDIR on a text editor showed files 
and directories out to about column 100.
Then I put in a deep scratch,about 1" long from edge to center
and tried again-took 4 min.-ended normally with no errors.
After some manipulation,I used COMPARE on  the two SAVDIR files 
and showed NO difference.
I conclude that DT.COM is not the answer.
 
I investigated some other DOS programs like DRS112,DTST20.
Some other programs like SCAV31,LISTB123,HDTST128,DIAG44, seemed 
only for the hard disk.I tried an old CHKDSK (got WRONG OS ).
I don't know waht I could do about questionable DVD disks.
 
 I came across MSCIENCE.COM with a wealth of information on
CD and DVD disks.It pointed to several sites that had DOS
programs for checking CDs:DISKDET.EXE,ASCVL.ZIP and CDCHECKSETUP.
EXE.I plan to setup my old DX-66 486 PC with a CD tray and try
again.In this operating system,DOS is at a higher level over 
WIN95 as compared to XP where DOS is an emulation.
One article from MSCIENCE warned against using any grinding on 
the surface to correct scratch errors.It said that you are adding 
a lot of tiny scratches that may be just as bad.I also understand
that the software for reading CDs,can correct for small scratches.
 
Invention
-----------
  When you get to be 80 years old,your body starts to fall apart
and occasionally ,I leak in the rear and soil my undershorts.To 
save aggravation from my wife,and after some trials,I got some
Shop Towels ( blue paper towels) from the Auto supply store.
I would open the shorts to expose the back,put in a paper
towel,and used 1 1/2" masking tape to fasten the towel.
After 2 years,it works very well.
 
 

--- Maximus 2.02