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Author Topic: THE VOICE module inside the G7400 ?  (Read 11945 times)
Rene_G7400
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« Reply #30 on: February 25, 2013, 03:53:36 PM »

And is there any reason to build the T0 switch as I don't use the RAMcart and there is no Basic module for the O2?

If you don't use a RAMcart you don't need the T0 switch, but you need another way to switch off the Voice, because some games contain errors which cause the Voice to make unwanted sounds.


A SPST manual switch on the +5 line to the voice would accomplish this, correct?

That's not a good idea, it would be better to interrupt the D5 line to the Voice with a switch and connect the D5 input of the Voice to ground with the same switch (databus line 5).
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Rene_G7400
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« Reply #31 on: February 26, 2013, 11:36:50 PM »

Should the audio out from the voice module (pin 7 of IC4) go in to a 330ohm resistor that connects to the O2 at C45/R49 junction and from there into the audio in of the mod board?

The G7400 with RGB output has a voltage divider on the audio output (two resistors: 1k connected to the sound output of the video chip and 330 Ohm connected to ground). You will need to do the same to connect the Voice output to it, but you might need to change the values of the resistors a bit for the right level and balance.
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gertk
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« Reply #32 on: March 03, 2013, 02:32:06 PM »

A SPST manual switch on the +5 line to the voice would accomplish this, correct?

No, that would leave all the electronics of the Voice dangling on the bus lines causing all kinds of unwanted loads and side effects.

If necessary you can put a switch somewhere in the audio circuit.
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
Rene_G7400
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« Reply #33 on: March 03, 2013, 06:56:16 PM »

If necessary you can put a switch somewhere in the audio circuit.

The disadvantage of that is that games that do automatic Voice detection still detect it. With the D5 switch mentioned earlier, the Voice won't be detected anymore.
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grips03
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« Reply #34 on: February 06, 2017, 06:17:40 AM »

Great thread.

Couple of questions: 

1) Looks like this mod is possible with Odyssey 2, using IC9 in lieu of RAM 6810.

2) Would it possible to remove LM386 amp, i.e. is sound loud enough when sending to TVs audio jack.  I was thinking of sending voice to left channel and right channel as O2 sounds.



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Rene_G7400
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« Reply #35 on: February 06, 2017, 12:47:30 PM »


1) Yes, IC9 is the same chip.

2) I think that removing the LM386 won't be a good idea, since there is a low-pass filter at the output of the Voice chip, so a buffer might be necessary. The Voice module of the Odyssey3 (which doesn't have to drive a speaker) also has an amplifier chip (although a different LM number).


Great thread.

Couple of questions: 

1) Looks like this mod is possible with Odyssey 2, using IC9 in lieu of RAM 6810.

2) Would it possible to remove LM386 amp, i.e. is sound loud enough when sending to TVs audio jack.  I was thinking of sending voice to left channel and right channel as O2 sounds.

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