I don't use tape in the project. To make a long story short, an mp3 player is connected to a picaxe, each mp3 files are different, right audio channel have the usual sound track, left one will contain the commands to send to the picaxe. The picaxe receive them, analyse them and control other devices base on each commands. each mp3 files with be generate first in an audio editor, something like goldwave, and will contains the commands in different orders, so each mp3 files have his own set of commands. Like a talking robot that will move with the commands.I think straight serin/serout onto a tape would work ... Tape recorders can handle that fine.
hehehe.. audio to serial converter, hehehe. This sound like really easy, arghh I envy you all to know so much about electronic, hehehe. The more I read an the more I see that it is above my electronic knowledge.... you send a group of 6-12 'U's at the beginning of a packet to bias things to half volts. Then a header like 'ABC'. Then the data packet. Then a checksum byte at the end. Those little packets are very short - you could have many per second, and each one could instruct the picaxe to do something different. A packet might be UUUUUUUUABC1236 where ABC is the header, 1 2 and 3 are the data bytes, and 6 is the sum of 1,2 and 3.
Oh oh!!! I have a LM324!!! ... humm.. now I need an oscilloscope, biasing something, then gain stage (and not weight), voltage follower, comparator and op amp theory.The audio stages might need some tweaking an an oscilloscope would be very helpful. But the output for instance would be a matter of biasing the signal to a virtual earth of 2.5V via a blocking cap and then a couple of 10k resistors. Then through a voltage follower. Then maybe a gain stage so the signal is going +/- 1V. Then a comparator. This could all be done with one LM324 chip costing 30c, but would require a bit of op amp theory.
Look like I'm about to faint again.. heheh.
Well, I see that this idea look at first easier than it would be. Atleast My knowledge of electronic is too small to get something working. I'm sorry that I made you loose your time everyone. You really tried to help, but I see that I unfortunately don't have enough knowledge and experience to achieve it at this time.