The LM3915 sound level meter is vocoderised and becomes a peak programme meter. I explain split power supplies, alternating current audio signals, and why op amp circuits often require positive and negative power supplies. Then I start singing. All very weird.
ETI Vocoder constructional project reproduced with permission from Wimborne Publishing Ltd. http://www.epemag.com

By Julian

Youtuber, shed dweller, solar charge controller aficionado

12 thoughts on “Ppm bargraph, op-amp, split psu and gregorian chant”
  1. Avataaar/Circle Created with python_avatars Naoki's Retro Corner says:

    Should have done the halo theme music with the echo, would have sounded great! 😉

  2. Avataaar/Circle Created with python_avatars David Legault says:

    Hi Julian, great video and explanation in pos/neg power supplies. Did you do a video on another karaoke board and if so which video was it. Regards, Dave

  3. Avataaar/Circle Created with python_avatars milesjwade says:

    Some pro audio mixers can switch the meters between PPM and VU modes. VU mode shows the RMS level, so it's a bit slower/smoother and will only show 3 dB below the actual peaks, whereas PPM mode is faster and shows actual peak levels.

  4. Avataaar/Circle Created with python_avatars Chris Phoenix says:

    funny vid lol

  5. Avataaar/Circle Created with python_avatars TubiCal says:

    You can easily omit a spilt voltage supply if you set up a virtual ground for them OpAmps. For basic usage by just using a voltage divider. and use it for your OpAmps as a ground path. Now you need to block the DC with capacitors, but that´s about it.

    Hopefully your ETI stuff is going to work. I had lots of trouble getting their stuff to work right when i built it….They kinda work but not as supposed to do, and add some flaws herre and there…

    Anyway good video, as always…:)

  6. Avataaar/Circle Created with python_avatars SoundsFantastic says:

    It doesn't detect distortion, it detects clipping. The speakers sound output is distorted.

  7. Avataaar/Circle Created with python_avatars Nathaniel Bajakian says:

    Julian, I'm just starting out electronics and I'm using a crappy wall-plug in variable power supply with no selection between 4.5 and 6v. What kit are you using here for the power supply, or what would you recommend for a very cheap power supply that provides 5v?

  8. Avataaar/Circle Created with python_avatars zebratangozebra says:

    That cap is absolutely fab !

  9. Avataaar/Circle Created with python_avatars pvc says:

    What is the chip in the preamp? How's the echo effect implemented?

  10. Avataaar/Circle Created with python_avatars NightReaper says:

    I dunno, I think the sounding better in the shower thing, like the negative voltage, is a relative thing 😛

  11. Avataaar/Circle Created with python_avatars NivagSwerdna says:

    I just can't believe the amount of electronics junk I have now ordered from China. Watching these channels should come with a health warning.

  12. Avataaar/Circle Created with python_avatars Cliff Matthews says:

    Bipolar rails may not always be required if you use capacitors (as isolating and level shifting devices). Input BJ transistors can then be biased at some positive level on a single-rail amplifier's voltage.

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