Accidental copy of Razmasynth Super Warp Generator...

[Hashtag Octothorpe]

Some flashing LEDs came in the mail and I could NOT remember the name of the project that had inspired the purchase, but turns out I basically recreated the Razmasynth Super Warp Generator.

So of course, instead of just the three parts (four -- I included a resistor to ground to complete the output high-pass filter) I built a seven-LED version with comparators to turn the LEDs on depending on a voltage provided by a knob or a control voltage.

I haven't tried the CV yet, but it might not work perfectly -- the comparators inputs and outputs swing between the + and - rails (as close as the NE5532s can manage, at least) and most CVs are either ground-to-10V or +/-5V but hey, this isn't a finely tuned precision instrument

Oh... and I don't know how common it is for NE5532s to spontaneously explode, but I've had it happen way too often, in one case after more than a year of working perfectly. So I include 220R resistors in series with the power connections now. No more magic smoke spontaneously escaping from mixers and LFOs

Here's a clip

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Description:	Similar to the Razmasynth design
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IMG_20200822_161654-01.jpeg
Description:	Complicated version. I built mine with SMD resistors and four dual op amps stacked on top of each other
Filesize:	668.85 KB
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[Grumble]

I just don’t understand how leds can make such a sound...

[JovianPyx]

[PHOBoS]

yep, see also : https://electro-music.com/forum/post-371779.html#371779
and this one by Ringmad https://www.youtube.com/watch?v=GE7RyhDhcyo

great idea using a bunch with some comparators and CV .
that might also be possible with an LM3914/LM3915.

[Hashtag Octothorpe]

Yup there's electronics in there that PWM the three emitters to get fading colors. That, and when the LED blinks ON-OFF-ON-OFF there's a "click click click". I haven't scoped it, but I assume when the LED is "off" the spot I'm taking audio off of is ground, while when any of the LEDs are "on" the audio spot is V+ minus the diode voltage drop.

Changing the voltage to the LED doesn't do anything interesting to the sound besides make it quieter.

Different LED thingies have different pitch, and there seems to be some memory when you pulse the LEDs -- they don't always seem to reset completely to the beginning of the pattern they play.

I played with the module last night, and the CV input works fine (although it does go between half-of-them-lit and all-of-them-lit with a unipolar CV, and none of my bipolar signals swing between +12V and -12V LOL) so... the dial will be fine. The CV input range could easily be adjusted by changing the values of the resistors at the "top" and the "bottom" of the comparator resistor ladder.

[Grumble]

Nice, thanks for explanation guys