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From: dollas@uiuccsb.UUCP
Newsgroups: net.micro.cbm
Subject: Re: 64 cassette interface kit - (nf)
Message-ID: <4851@uiucdcs.UUCP>
Date: Tue, 10-Jan-84 22:29:32 EST
Article-I.D.: uiucdcs.4851
Posted: Tue Jan 10 22:29:32 1984
Date-Received: Sun, 15-Jan-84 00:45:08 EST
Lines: 27

#R:ariel:-53600:uiuccsb:16800006:000:1417
uiuccsb!dollas    Jan  7 18:20:00 1984

   In the previous response the setting of volume levels appears
to be the problem (as I mentioned in my previous note it does take
time to adjust it); if the design with the op-amps works better, by
all means go for it. By the way there is no address of the sender,
could I have a copy of that design?
   By the way it just occured to me that the design in the Popular
Electronics article does not work with tapes pre-recorded on 
other cassette recorders because they invert the signal once in the
recording and once in the playback. If the signal is double-inverted
in the recording AND double inverted in the playback it should work;
at least I had no problems with the company's tape of the Victerm 
program. The 7414 chip that is used has six gates anyway, so there is
plenty of gates (actually I use one of the spares to dub a tape to 
another while it is loading).
   Just trying to guess, the circuit with the op-amps seems to me that
would be based around either a diff-amp or zero crossings (in order
to get the TTL levels the Commodore wants). Does this work with the
+5v the Commodore provides or an external source is needed? is there
a Schmitt trigger buffer to (and from) the Commodore? I am very 
curious about this design, so please don' let me hang by my thumbs.

                                      Apostolos Dollas

      (my address and path is in the first response of this message)