Cassette recorder replacement?

Discuss the CreatiVision hardware: models, revisions, fixing, hacking and modding.
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carlsson
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Cassette recorder replacement?

Post by carlsson » Fri Jun 13, 2008 9:08 am

Does anyone know if it is feasible to wire a regular cassette recorder to the creatiVision console? I've come as far as looking at some schematics and found which pins on the edge connector should be used, but I'm unsure if the original recorder contains its own A/D converter or if the console converts the audio signal to data.

Alternatively, I suppose I could buy a recorder if anyone has spares but I get the impression it is a somewhat uncommon peripheral?
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giovortu
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Re: Cassette recorder replacement?

Post by giovortu » Sun Jun 15, 2008 7:00 am

Hi carlsson.

CreatiVision sends raw bits data to cassette recorder (no DAC nor ADC), which has only some amplifiers inside to drive magnetic r/w heads, plus a control line that turns motor on/off, with just some transistors to drive it.
I've never tested it by myself, but i think it's possible to connect a general purpose cassette recorder using a low impedance i/o ( to be clear, not headphone output but line-in / line-out ).
Tell me if you need more documentations about cassette recorder hardware.

Giovortu
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Bill Loguidice
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Re: Cassette recorder replacement?

Post by Bill Loguidice » Thu Feb 02, 2012 4:13 pm

If anyone has a cassette recorder for sale or has developed an adapter to use another type of device, I'd love to know about it as well. Right now that's the last piece to being able to use my Wizzard as a full computer.
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Scouter3d
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Re: Cassette recorder replacement?

Post by Scouter3d » Thu Mar 08, 2012 9:27 am

Hi,

After a lot of struggle, i was able to load programs from my computer (soundcard) to the Creativision (DSW) tapeconnector!
But beware it is not as easy as a "Line-in / Line-out" connection!

You need only two pins of the tapeconnector (the first (from the front) is GND and the one before the last pin is the signal).

I used my trusty MACKIE mixer to amplify and "shape" the signal. I used the "lunar lander" file from this site and i had the use the preamplifier nearly to its max-setting (wich resulted in a more square wave, where top and bottom of the sinewave are "cut" and i attenuated the high frequencies which made the "flanks" of the wave steeper. Then i had to crank up the volume of the main output a lot! (the signal was oscillating between 0 and 15V - i dont think that´s really good for the I/O Chip!?!) nearly to the topmost LED on the meter.

And then it loaded!

Will try more ...

See attached pictures.

Greetings TOM:-)
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MADrigal
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Re: Cassette recorder replacement?

Post by MADrigal » Thu Mar 08, 2012 6:34 pm

This is really great news, Tom! :-)

Did you notice that many Creativision tapes have signal on both left and right channel?

On commercial tapes, one channel is used to output loading music/speech into the RF modulator. The other one contains the real program data.

In case you wanted to read WAVs of commercial tapes, I suppose you should first work on the WAV files and exclude the audio channel.

As for the pre-amplified signal, I'm not into that matter, Giovanni is more expert than I :-)

PS: congratulations on your success and the wonderful desk! :-)
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Bill Loguidice
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Re: Cassette recorder replacement?

Post by Bill Loguidice » Thu Mar 08, 2012 8:46 pm

Wow, this is a huge step! I wish you continued progress to hopefully (eventually) something sell-able!
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Scouter3d
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Re: Cassette recorder replacement?

Post by Scouter3d » Fri Mar 09, 2012 7:32 am

Hi Bill,

I will try to rebuild the internal amplifier of the Tapedeck and try to build a small circuit around it to connect a standard taperecorder ...

Greetings TOM:-)
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Scouter3d
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Re: Cassette recorder replacement?

Post by Scouter3d » Fri Mar 09, 2012 12:08 pm

Hi,

During my testing i found out, that it is possible to "fastload" the creativision programms at twice the speed!!!!!
As i accidentaly loaded a 22kHz File into my 44KHz project (so its duration was halved) but it still loads!

Will keep on testing ...

Greetings TOM:-)
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Scouter3d
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Re: Cassette recorder replacement?

Post by Scouter3d » Fri Mar 09, 2012 12:15 pm

Just an idea ....

The Creativision sends raw bits to the tape and i think it likes to get raw bits back ... so maybe it is possible to store the raw data digitally and not analog? like on a PC with e terminalprogram via a serial connection ... => no more bad volume! or read errors ...

A little problem is because there is no such thing as a handshake or a common protocol.

Just thinking about it ...
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Scouter3d
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Re: Cassette recorder replacement?

Post by Scouter3d » Fri Mar 09, 2012 2:50 pm

Update:

First i managed to get good results using my hightech soundcard with a samplerate of 96kHz and 24bit. For recording i had to decrease the volume and for playback i had to increase the volume ...

Then i inserted a simple 1.2kOhm resistor between GND and the Soundsignal ... now i only had to increase the volume during playback a bit ...

I tried the same procedure with 44kHz 16bit and it worked perfect (only needed to increase the volume on playback)
I haven´t tried the same procedure with a taperecorder, because i don´t have one at hand...

I tried to load the "lunar lander" file (only 22Khz) and i recognized the difference in signalform see attached picture:
1. file: Program recorded using my 1,2kOhm resistor method
2. file: unaltered Lunar lander (only converted to 44kHz for easier compare)
3. file: lunarlander with a gain of +12dB (with a lot of clipping)

Maybe the internal amplifier on the tapemodule makes nice square waves out of the sinwaves ...

Greetings TOM:-)
PS: More to follow...
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