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Thread: PET 2001 Sound

  1. #11

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    I've seen 2001s with CRTCs.... But of course someone swapped parts.

    You know, I was up to me earballs in cheap computer speakers at one point. Just lately I've been finding a ton of uses for them but I must have pitched most of em. But this, why on Earth didn't I ever think to use them for this? That's brilliant. (Obviously I'm not!)

  2. #12
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    Ok, thanks guys. Just needed confirmation.

  3. #13
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    This thread has gotten me curious about what else for sound you can get out of a PET.
    Does the amount of glue needed to add a simple sound chip like a YM2413 make better-than-beeper sound impractical?

  4. #14
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    Well people have integrated the SID chip into the PET.... Somehow

  5. #15
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    You can add the YM2413, SPO256 speech (or many other devices) to the PET. You can either use the User port, or make the device look like a memory mapped device hanging off the memory expansion bus.

    The only issue you will have is that you will have to write your own software for it.

    Dave

  6. #16

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    Quote Originally Posted by VERAULT View Post
    Well people have integrated the SID chip into the PET.... Somehow
    That's surprisingly easy (65xx is that way ). But I wouldn't do it. SIDs are too rare to be using this way now, and software support is scarce.

  7. #17
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    Quote Originally Posted by KC9UDX View Post
    That's surprisingly easy (65xx is that way ). But I wouldn't do it. SIDs are too rare to be using this way now, and software support is scarce.
    Im not saying i disagree. But i now have about 7 or 8 working C64's and only one PET. Sids i have.. Software to run on a pet with a SID not so much...if i had an actual use maybe.

  8. #18

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    Quote Originally Posted by daver2 View Post
    They will be passive - just a simple piezo transducer.

    I (personally) wouldn't just wire CB2 straight to the piezo transducer, but would implement the circuitry found on the 8032. This would be just the addition of an SN74LS00 in addition to the resistor and piezo transducer. You will obviously require +5V and 0V to feed the supply lines to the IC. Alternatively, in place of the IC, you could use a common general-purpose NPN bipolar transistor with something like a 470 Ohm to 1 kOhm resistor from CB2 in series with the transistor base. Connect the emitter to 0V and the collector through the resistor to the piezo transducer to +5V.

    Dave
    Mimicking the 8032 circuit sounds like a really good idea. I found the 8032 schematic on zimmers.net.

    If I'm reading it correctly, I would wire up the circuit as follow:
    74LS00-PIN1 <---> PET User Port CB2
    74LS00-PIN2 <---> UB12 6520 chip PIN9 (PA7)
    74LS00-PIN3 <---> 10 Ω resistor <---> Speaker (+)
    74LS00-PIN7 <---> GND
    74LS00-PIN14 <---> VCC (5V)
    Speaker (GND) <---> GND

    Is this correct? What type of speaker (size, resistance -- 4Ω or 8Ω) is appropriate?
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  9. #19
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    Itís not a speaker, but a piezo disc...

    Have a look on the internet for pictures of a Commodore PET 8032 main board and you should see what I am talking about.

    And your proposed wiring looks fine. My original post had the piezo disk wired to +5V. Now I look at the schematic again it is 0V (as you have identified in your post).

    Dave

  10. #20
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    Quote Originally Posted by tanuki View Post

    What type of speaker (size, resistance -- 4Ω or 8Ω) is appropriate?
    To drive an 8 Ohm speaker, you would need to include an amplifier chip, or but since the CB2 line goes out to pin M of the J2 User Port, you could probably use a small external amplifier/speaker connected by a simple home-brew cable. You might want a battery powered speaker so you don't need to bring +5V out of the PET although it is available on the Cassette Port.

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