6 ms·

Hardware Reverse Oscilloscope 2

89 points by KANahas 3y ago

zx8080 3y ago
Is there some recommended way of fixing the power source noise issues?
- al2o3cr 3y ago
  The quick prototype in TFA is essentially a bunch of components connected together with long antennas, so literally any construction technique better than that will help...
nyanpasu64 3y ago
You can emulate waveshapers with steeper aliasing falloff than 6dB/octave, using integration-based techniques to calculate the average output value of a waveshaper when interpolating multiple input points (or something like that). There's a paper describing various orders at http://dafx16.vutbr.cz/dafxpapers/20-DAFx-16_paper_41-PN.pdf http://dafx16.vutbr.cz/dafxpapers/20-DAFx-16_paper_41-PN.pdf (if I remember the right link, RIP it's not HTTPS).
demondemidi 3y ago
This is a pretty complex build to throw together in such a short time, and it is super impressive I could have sworn I saw Morton Subotnick performing with something like this back in the 80's (with Electric Phoenix, maybe?) but Googling is giving me nothing. Does this ring any bells for electronic music fans?
zh3 3y ago
Reminds me of a fully-analogue approach to generate arbitary waveforms using a cardboard template stuck to the front of an oscilloscope. Basically, cut out the desired shape, stick it on the 'scope and point a photocell at the screen. The photocell drives the Y axis in a feedback loop so the spot height is a function of brightness -the idea being that the spot rides along the top of the template maintaining a constant brightness (with X timebase setting the output frequency - fairly obviously, needs an analogue 'scope with fully variable timebase). Could probably do it with a flexible curve these days, to save on the scissors and cardboard.
hulitu 3y ago
> Hardware Reverse Oscilloscope 2 A hipster name for a frequency synthetiser. /s
- crote 3y ago
  Arbitrary waveform generator, actually.
_kb 3y ago
The modular synth referenced as the muse for this is pure art: https://www.nervoussquirrel.com/modular https://www.nervoussquirrel.com/modular. Particularly love the uranium ore + Geiger counter random voltage generator.
- defrost 3y ago
  Well there's a rabbit hole. It all made sense when I realised he (the nervous squirrel) did similar work to a friend of mine; the old "anything anytime" gadget building for TV ads, movie props, coporate art installs, etc. https://www.youtube.com/watch?v=6RMlmYwFkZ4 https://www.youtube.com/watch?v=6RMlmYwFkZ4
lnsru 3y ago
When I look at the diagram I think, that this would be perfect introductory FPGA project. It is interactive, so it’s fun for the designer. Plus it touches digital signal processing and interface to external components. Such project is super cool compared to all other introductions I saw before.
- rasz 3y ago
  harder to develop and ~6x more expensive (DE10-Nano vs teensy + pico)
  - crote 3y ago
    You can get an UPduino for $30, that's probably plenty of FPGA for a project like this.
skeltoac 3y ago
See also the MIDI slide whistle by the same artist. Hilarious and very smart. https://mitxela.com/projects/slide https://mitxela.com/projects/slide
witherk 3y ago
The sound of the synth was so much louder than his voice that the video gave me a low grade headache.

89 points by KANahas 3y ago

zx8080 3y ago

Is there some recommended way of fixing the power source noise issues?

al2o3cr 3y ago
The quick prototype in TFA is essentially a bunch of components connected together with long antennas, so literally any construction technique better than that will help...

nyanpasu64 3y ago

You can emulate waveshapers with steeper aliasing falloff than 6dB/octave, using integration-based techniques to calculate the average output value of a waveshaper when interpolating multiple input points (or something like that). There's a paper describing various orders at http://dafx16.vutbr.cz/dafxpapers/20-DAFx-16_paper_41-PN.pdf http://dafx16.vutbr.cz/dafxpapers/20-DAFx-16_paper_41-PN.pdf (if I remember the right link, RIP it's not HTTPS).

demondemidi 3y ago

This is a pretty complex build to throw together in such a short time, and it is super impressive I could have sworn I saw Morton Subotnick performing with something like this back in the 80's (with Electric Phoenix, maybe?) but Googling is giving me nothing. Does this ring any bells for electronic music fans?

zh3 3y ago

Reminds me of a fully-analogue approach to generate arbitary waveforms using a cardboard template stuck to the front of an oscilloscope. Basically, cut out the desired shape, stick it on the 'scope and point a photocell at the screen. The photocell drives the Y axis in a feedback loop so the spot height is a function of brightness -the idea being that the spot rides along the top of the template maintaining a constant brightness (with X timebase setting the output frequency - fairly obviously, needs an analogue 'scope with fully variable timebase). Could probably do it with a flexible curve these days, to save on the scissors and cardboard.

hulitu 3y ago

> Hardware Reverse Oscilloscope 2 A hipster name for a frequency synthetiser. /s

crote 3y ago
Arbitrary waveform generator, actually.

_kb 3y ago

The modular synth referenced as the muse for this is pure art: https://www.nervoussquirrel.com/modular https://www.nervoussquirrel.com/modular. Particularly love the uranium ore + Geiger counter random voltage generator.

defrost 3y ago
Well there's a rabbit hole. It all made sense when I realised he (the nervous squirrel) did similar work to a friend of mine; the old "anything anytime" gadget building for TV ads, movie props, coporate art installs, etc. https://www.youtube.com/watch?v=6RMlmYwFkZ4 https://www.youtube.com/watch?v=6RMlmYwFkZ4

lnsru 3y ago

When I look at the diagram I think, that this would be perfect introductory FPGA project. It is interactive, so it’s fun for the designer. Plus it touches digital signal processing and interface to external components. Such project is super cool compared to all other introductions I saw before.

rasz 3y ago
harder to develop and ~6x more expensive (DE10-Nano vs teensy + pico)
- crote 3y ago
  You can get an UPduino for $30, that's probably plenty of FPGA for a project like this.

skeltoac 3y ago

See also the MIDI slide whistle by the same artist. Hilarious and very smart. https://mitxela.com/projects/slide https://mitxela.com/projects/slide

witherk 3y ago

The sound of the synth was so much louder than his voice that the video gave me a low grade headache.