Image Map Image Map
Page 1 of 4 1234 LastLast
Results 1 to 10 of 37

Thread: PET 2001 Sound

  1. #1

    Default PET 2001 Sound

    Hi,

    I've found a number of suggestions for how to get sound out of my PET 2001-8. The easiest one I found on this VCFed archive.

    Here's a quick look at the suggested circuit:
    PET User Port CB2 line -----> 20 ohm resistor ------> (+) PIEZO BUZZER (-) ---------> PET User Port GROUND

    The question I have is whether the piezo buzzer called for in this diagram should be an active piezo or a passive piezo. Does anyone know?

  2. #2
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    3,178

    Default

    It depends what you want it to do...

    An active piezo has an internal oscillator, so the PET will only turn on and turn off an active piezo buzzer.

    A passive piezo requires the PET to turn on and off the signal to make an audible sound. The advantage of this is that the frequency can be controlled by the software on the PET.

    An active piezo is (in my opinion at any rate) louder than the passive equivalent, but less flexible.

    Does that help, or raise more questions?

    Dave

  3. #3
    Join Date
    Mar 2017
    Location
    New Jersey, USA
    Posts
    518

    Default

    In this context, I think passive is what's needed. The piezo buzzer here is substituting for a larger speaker (and a transistor to provide enough current to drive it).

  4. #4

    Default

    Thanks Dave & kgober.

    I'm looking to add sound to games such as Space Invaders and demos such as "No Pets Allowed". Any idea whether these programs are using an active or passive piezo approach to generating sound?

  5. #5
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    3,178

    Default

    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

  6. #6
    Join Date
    Jan 2012
    Location
    Connecticut, USA
    Posts
    2,296

    Default

    Quote Originally Posted by tanuki View Post
    I'm looking to add sound to games such as Space Invaders and demos such as "No Pets Allowed"
    I was told the no pets allowed demo would not work on a pet 2001 so i never attempted it. Am I wrong because i would love to try it out.

  7. #7

    Default

    Quote Originally Posted by VERAULT View Post
    I was told the no pets allowed demo would not work on a pet 2001 so i never attempted it. Am I wrong because i would love to try it out.
    I assume it requires CRTC. If your 2001 has that, it'll work. If not, it sure won't do what it's supposed to do.

  8. #8
    Join Date
    Jan 2012
    Location
    Connecticut, USA
    Posts
    2,296

    Default

    CRTC? Can you expand on that? I have a 2001-8 but I also have the tynemouth software RAM/ROM board as well.

  9. #9
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
    Posts
    7,211

    Default

    Quote Originally Posted by VERAULT View Post
    CRTC? Can you expand on that? I have a 2001-8 but I also have the tynemouth software RAM/ROM board as well.
    CRTC= cathode-ray tube controller. If it's a 2001 it doesn't have one; if it has one it ain't a 2001.

    I'd just hook a cheap pair of computer speakers to CB2.

  10. #10
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    3,178

    Default

    +1 Mike!

    Good idea.

    Dave

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •