[sebhc] H8-5

[Carroll Waddell]

dwight elvey wrote:
>
>
>
>> From: Carroll Waddell <carrollwaddell at sc.rr.com>
>>
> ---snip---
>>
>> At this point, all I'm trying to do is make the H8-5 think something 
>> else is a cassette player.
>> I'm trying to feed the H8-5 AUDIO INPUT with tones just like the 
>> sound coming from a cassette player.
>> The audio from an actual cassette is not sync'd to anything. The PLL 
>> on the H8-5 creates the clock from the audio coming from the cassette 
>> player.
>> I haven't started to try to create the WRITE half of the project yet. 
>> I'm still just trying to make the H8 think I have an actual cassette 
>> player with a tape to load in it.
>> Carroll
>
> Hi Carroll
> One other thing to try is that the complete system with tape recorder
> included assumes some rolloff is needed to send to the tape recorder.
> If you look at the output of the H8-5 should see a resistor/capacitor
> filter. Your circuit should match this before sending data to the input
> of the H8-5. The H8-5 is expecting to compensate for this filter.
> How many cycles of tone are used for the input? I have a Poly88
> tape input that is sensitive to the polarity of the audio coming in.
> You might look at inverting the data as well.
> One last thing. You might check that it still works with a real cassette.
> It just might be that it has died.
> Dwight
>
>
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It is possible that the signal I'm feeding to the H8-5 isn't a pure sine 
wave.  The output from the H8-5 card that normally gets recorded to tape 
comes from the RC network output of the card.
This isn't a pure sine wave. By the time the tape recorder records it 
and plays it back, it is very much closer to a sine wave.

I think I'm going to record a real tape output and my device output into 
a PC so that I can examine the waveforms in detail. Maybe I'll see some 
difference.

Bill Elkins suggested that the H8-5 card only changes frequency at the 
zero crossing point. That's why I want to look at the waveforms.

Carroll
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