I made a few modifications and discovered a footprint error. The BF245A footprint is backwards. I realized that it has the same pin out as the 2N5485 I’m using, yet it only worked when put in backwards. Cross referenced the schematic with the data sheet and sure enough. It’s erroneous. You should probably update the files on GitHub.
I also tried switching it out with a 2N5951 and a PN4393—both with good results—but ultimately decided the 2N5485 worked the best.
I also swapped in BC550C’s for Q1 and Q2, but it made no difference in terms of driving anything but a modern red LED.
Finally, I switched the 100nF C6 for a 220nF to get a better range and rate (so, half the speed, just about). I also tried a 470nF, but it diminished the range too much and took the rate adjustment out of the sweet spot.
So, other than the LED, it’s all good now.
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Awesome work man!
I will try to get at the files tomorrow on GitHub!
I will make a note of it on there as well!
Time to load up that ole file and get to work lol
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So a list of Errors:
- BF245A Footprint is Backwards
- C6 - 220nF
- Range and Rate are Mislabeled
- Both Pots Wired backwards * edit
@ChristianBloch am I missing anything?
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Yeah, both pots are backwards 
. The 220nF is just a preference, but it works for me. Still not sure what’s up with the LED voltage being so low.
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Do you know the output voltage of the opamp driving the transistor? You need at least 3V5 (Vbe + resistor + LED drop) to light up the LED.
You can also try to lower the 100k resistor (R26?) to 47k or even 10k.
If you want an early response (start at around 1V):
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I just finished the colored noise module by Niklas Ronnberg and have encountered a weird problem. I finished and tested it to verify it was working, the red, blue, and pink noise outputs work great and sound great. However, I have a completely different circuit that it outputting white noise separately as well as being inputted into the module and it works fine. So even with a completely different circuit being used as the white noise source on the module, it works fine. The problem came when I tried using the same white noise source and the power powering the different circuit to another circuit, which was was outputting different kinds of colored noise, and it still worked. But when I disconnected that circuit form the white noise source and tested the Niklas Ronnberg circuit again, all the output signals work except the red noise output. It is strange because the other circuit I was testing didn’t seem to affect the white noise source or the Niklas Ronnberg circuit and still worked fine, but for some reason I can’t get red noise anymore. I tested everything to make sure everything was still connected and there were no changes in value, to find everything was fine. I even changed the TL074 chip to find all outputs still working but the red noise output. Does anyone know why this might be happening or any kind of potential solution?
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