Cassette Interface

Talk about your Micro-KIM

Cassette Interface

Postby Norbert » Mar Wed 16, 2011 5:02 pm

Hi all,

tonight I was able to finish the 'prototype' of the cassette interface for my Micro-KIM. :D
First tests in storing and re-loading shorter programs using my computers' soundcard were successful.
Problems left for tomorrow: exact tuning of the PLL and elimination of electrical interference caused by the connection to the soundcard.

Has someone got a original kim soundfile for me to proof if my interface is really compatibel?

Cheers,
Norbert
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My Micro-KIM with interface
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Re: Cassette Interface

Postby vbriel » Mar Thu 17, 2011 9:59 am

Nice work. I'm trying to get the cassette board started for summer but I'm been really busy these days. I do like seeing others complete it in prototype format, great work. I think I remember seeing audio files out there but I can't recall where.
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Re: Cassette Interface

Postby Norbert » Mar Thu 17, 2011 1:51 pm

Today I got rid of a ground loop and then tuned the PLL. I suppose the interface will work with a real cassette tape recorder instead of a sound card, too.
To improve the reliabilty it is helpful to put a 8 ohm resistor across the input of the interface to simulate the missing recorder speaker (as much as I understand this is necessary because of the missing voltage drop). In a different context (FSK demodulator) Elektor recommends anti parallel diodes to discriminate the input signal. But I haven't tested this yet.
To solve the +12 Volt problem I used a dc converter (LT1073). I took the PLL layout of the Elektor Junior Computer, not of the KIM. But I think they are nearly the same.

Cheers Norbert
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Re: Cassette Interface

Postby hanso » Mar Mon 21, 2011 3:57 pm

Norbert wrote:Hi all,

Has someone got a original kim soundfile for me to proof if my interface is really compatibel?

Cheers,
Norbert

Great work!

I have put online two KIM-1 sound files, see my forum at retro.hansotten.nl

Hans
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Re: Cassette Interface

Postby Norbert » Mar Tue 22, 2011 5:17 am

Thank you, Hans.
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Re: Cassette Interface

Postby markboston » Jul Fri 15, 2011 12:44 am

any ETA on when this will be finished so we can have a cassette board to use for storage?
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