A TRANSISTOR-LESS SOUND SYNTHESIZER

Steveg · Joined: Apr 23, 2015 Posts: 184 Location: Perth, Australia

Did anyone notice this? https://hackaday.com/2020/10/24/a-transistor-less-sound-synthesizer/

I'm wondering if the supply voltage across the two oscillator LEDs needs to be less than the sum of the voltage drop across them so both don't light up at the same time?

But a very cool bit of noise maker.

dk · Joined: Feb 12, 2019 Posts: 115 Location: Europe

Oh, cool. Awesome drone sounds!

On his schematic it looks like they're getting 5V: https://cdn.hackaday.io/images/5964711602672729170.JPG Since it looks like he's using blue LEDs, I guess that would be the case?

Steveg · Joined: Apr 23, 2015 Posts: 184 Location: Perth, Australia

That was my thought as well but nowhere is that called out in Dr Cockroach's or Patrick Flett's videos.

And confirmed by Patrick as a requirement.

dk · Joined: Feb 12, 2019 Posts: 115 Location: Europe

Thinking about it further, I'm curious what kind of levels he's getting out of this. The LDR's I have can't make it into audio rates period, but assuming he's using something faster, I can't imagine much swing coming out?

Also, his RTA isn't using a very narrow resolution, but it seems that there is at least a few octaves of harmonics on top, mixed in with noise - most of which I would guess is attributed to the diodes. I'm wondering if you couldn't get similar sonic results by just running a triangle wave through a bridge rectifier without dealing with the rest of the mess. I know that it would lack the novelty, but you'd get a lot more range with a lot less fuss.