e-licktronic Forum

I also had the same issue as MeToo. The minimum voltage I could adjust the trimmer to was about 500mV.

I replaced Q35 with a BC549 I had at hand. Now I can tune the noise from 50mv to over 1V with the trimmer. On the scope, it looks like noise with no DC offset.

I am currently finishing the sequencer and it seems, that I have a spare 2SC945. Perhaps I will use that for Q35. I will get everthing going first and then check if there is any noticable difference between the BC549 and the 2SC945.

Old topic, sorry but just wanted to point out that as far as I understand, the 2SC828 in the noise section is selected because of its noise characteristics so while an SC945 or something else may allow a user to dial in the correct mV, the characteristic sound of the whole instrument is likely to alter. I cannot verify this first hand since I am amidst my build.

With the supplied 2SC828 I could only get a minimum of about 300mV at the noise section. So I bought a load of 2SC828 on eBay and now I can easily find several from that pile that allow a good range with the trimmer (I put a socket by Q35), allowing a 130-ish MV setting. So if anyone should be flummoxed by the noise section and find this thread, first ensure you've done the service manual noise section modifications and then just find some other 2SC828 to dial in the noise section as specified. 2SC828 are quite easy to find on eBay. If you're really stuck, I'm in the UK - let me know.