Subject:
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Re: RCX sound circuit
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 25 Jun 2005 15:35:40 GMT
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Viewed:
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1102 times
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In lugnet.robotics, Philippe Hurbain wrote:
> In lugnet.robotics, John Reynolds <john-reynolds@rocketmail.com> wrote:
> > I was getting to the point where I could generate a
> > number of similar friendly sounds and then the RCX
> > stopped generating sounds completely (except for beeps
> > from the On-Off button when pressed). This happened
> > within an hour!
> >
> > I can only assume that the repeated intensive use of
> > the oscillator circuit has burnt out some component.
> > All other functions of the RCX seem to be intact.
> >
> > Does anyone know the location of a circuit diagram for
> > the RCX?
>
> Here is the sound driver section:
> http://www.brickshelf.com/gallery/Philo/RCX-comp/sound_driver.gif
> (Mark Bellis, if you read this you can add this schematics to your RCX circuit
> collection to get everything together)
>
> It seems impossible that you have fried anything if you still get on/off sound:
> there is only one buzzer driven by a simple circuit, so the hardware can't be
> wrong here (and I don't think it could ever get "tired" with the 330 ohm series
> resistance...)
>
> So I suggest you follow Claude's suggestions who posted while I wrote this ;o)
>
> Philo
Your circuit diagram checks out Philo, though a 47k resistor to ground should be
added to the processor connection. As soon as I get access to Visio again, I'll
write it up and post it with a credit.
I was wondering what the other NAND gate is used for. Input pin 1 traces to
somewhere under the ROM. Input pins 2 and 13 and output pin 12 disappear
elsewhere.
I suggest that a 3-input NAND gate was needed by the main computer circuit and
that the speaker driver circuit just mopped up the spare gates. The speaker
circuit is effectively an H-bridge design, using the CMOS output stages of the
two gates, which allows 10 volts differential across the speaker and series
resistor.
Mark
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Message has 1 Reply:
 | | Re: RCX sound circuit
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| Hello Mark, (...) Quite possible as I obtained the schematics only with an ohmeter... (...) I spent some time again with my ohmeter, here is the schematics for this part: (URL) is the motor driver control circuitry, data is latched when there is a (...) (19 years ago, 27-Jun-05, to lugnet.robotics)
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Message is in Reply To:
| | Re: R2D2 Sounds - A Warning my RCX has laryngitis.
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| (...) Here is the sound driver section: (URL) Bellis, if you read this you can add this schematics to your RCX circuit collection to get everything together) It seems impossible that you have fried anything if you still get on/off sound: there is (...) (19 years ago, 22-Jun-05, to lugnet.robotics)
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