Introduction to Dave from SpectrumDIY

[SpectrumDIY]

So… I managed to get SOME noise, and it seems to be changing in frequency to the CV…

I’ve run out of steam for today, but here’s what I’ve got. And I know it’s ugly, but nothing is shorting on the top of the board.

I’m not entirely sure why it’s not working, given that everything seems to be in order. But there again, this is only the second board I’ve tried, and the diagram is in stripboard.
I’m autistic if I haven’t already said so, one of the things I struggle with is comprehension, once I get past that, I’m golden.

Anyway. Here’s the pictures.

[SpectrumDIY]

Ignore the top left corner, it isn’t actually affecting it as that’s the 470r/10nf cap

EDIT:
My apologies, it’s from here:

STUFF - LOOK MUM NO COMPUTER

Using the PWM CV/Square out

[twinturbo]

Always best to post up your source material for the schematic.

It’s quite difficult to diagnose a strip board but we have managed to help in the past.

[Dave]

The resistor between B7 B17, are the colours brown, black, black, red, brown.

It is not clear in the photo?

[Dud]

Welcome in the forum

I don’t see (maybe under the wire) the little wire between pin 1 & 2

[KardashevTypeII]

Welcome to the forums. I’m @KardashevTypeII a.k.a. Fumu/Esopus.

[SpectrumDIY]

It’s a 10k resistor next to a 470k resistor in response to Dave

@Dud Thank you!
And the circled wire you show, is this one in red

Thank you for the welcome @KardashevTypeII

My apologies for the delayed response, I was up until ~0430 (central time), just getting the gears turning good, it’s 14:45 now. I managed to get some type of response out of it before I crashed, but I haven’t had a chance to triple check everything.

So far it’s not oscillating at all, and there’s loud noise almost as if the amp isn’t grounded somewhere, there’s a response as I said but it’s hard to tell exactly what’s going on (for me anyway)
If you’d like, I might can post a video on what’s going on, might help. I don’t know… but I didn’t want to ask for help and sound needy. I just wanted to share what’s going on XD
I do try to do it on my own to the best of my ability… though admittedly I’m struggling with it.

I did cave and order stripboard yesterday, so if I just absolutely can’t get this board working (which is only the second attempt, so I’m not upset or anything, these things happen) I’ll at least be able to make it that way, which might be easier to build since the layout is in stripboard.
I prefer to use what I’ve got on hand as I am very broke indeed. But it happens…

My entire goal with this project (short term) is to get something playable for halloween for the kids, beyond just the 20 oscillators, was hoping to build the VCO so that it can be sequenced with my beatsteps.

The long term goal is hopefully to evolve it into a full synth for making soundscapes. It doesn’t have a set expectation in that regard as I want to enjoy the process and not put on tons of restrictions and unmanageable expectations. But one baby step at the time XD (I tend to charge full speed ahead and just tackle the project and then workout the problems along the way

My apologies for the info dump, I was trying to keep up and then my ADHD hit and it was time to tinker, then when I tried to reply, I didn’t know I had hit a reply limit (whoops, I am so sorry, I wasn’t trying to spam)

Honestly I still haven’t looked at it today, I’ve been allowing myself a little bit of a break from it, hoping to hit it with fresh eyes this evening

[SpectrumDIY]

Updated with pictures so it’s easier to see

https://cdn.discordapp.com/attachments/881612615057563648/901306225654915162/P1100645_4.jpg(image larger than 4 MB)

https://cdn.discordapp.com/attachments/881612615057563648/901305748364083250/P1100647_1.jpg(image larger than 4 MB)

[SpectrumDIY]

Turns out my power supply isn’t even giving me the -12V I need … so I don’t have any power to the negative… that might be a huge factor here.

[analogoutput]

Have we got a topic for you

Power supplies choices?

so im starting this topic as I get a lot of questions regarding power supplies, and there are a heck of a lot of options! the great thing is with this format is the power supply is the same as eurorack. so with that in mind. you can use the options open to eurorack. I guess it limits out things like the 4ms power as that has a eurorack power input module. but there are lots of options! the go to for me is the mfos style wall wart power supply and I always suggest either the wall wart one by mf…

[SpectrumDIY]

Cheers! That’s exactly what it is, it could be working perfectly fine but not have the power it needs because I’ve went over it all day long and there’s just nothing wrong that I can see, meter checks out okay, so all that’s left is to get a proper power. Had no idea I was not getting negative voltage

[SpectrumDIY]

Small update, turns out I had a ATX power supply on hand, so naturally I probed around and tested it, though it’s totally gone except the +5v, so I finally just caved and ordered another ATX, mainly because I can use it for other things as well…

So the project is on hold until that power supply gets here… Tis a shame the one I’ve got doesn’t work D:

Ahhh, I am only just now starting to see why they sell dedicated synth PSUs for so much… But I’m still going to ATX route XD

Cheers for all of the advice and help! I am going to leave the board alone until the power supply gets here, I really think it should be okay… I’ve gone over it so many times I can almost see it in my head and the only thing that is wrong, is the lack of -12v power, which I’m sure you more experienced know exactly what struggle I’m dealing with XD

Anyway, hopefully update on the project soon!

[analogoutput]

Have fun waiting for the PSU! If there are further troubles after that, best to post about them in an existing topic like this one

CEM 3340 simple VCO

On the Strip board layout it calls for a .1nf Cap , but on the BOM it states 1nf , which one is it ? Cheers Daryll

for easier finding by future readers who may learn from your experience. Also check

General advice for troubleshooting a module and asking for help

(This is a wiki post, please add and correct!) Look and see if others have had the same problem. Use the Discourse search facility to find topics where the module you’re building is discussed. Inspect your work. Verify all components are correct values. Look for solder connections that are rough, irregular, skimpy, dull, or missed completely (we all do that!) and reflow them. Look for solder bridges between pads and remove them. Check your power connection. If it’s a Eurorack style power cabl…

and

Advice for troubleshooting 3340 based VCO

This is a wiki post; please correct and improve! This is written regarding the 1222 Performance Oscillator module, but similar things apply to the simple stripboard oscillator or other oscillators based on the 3340 chip. For the stripboard version also see If you are not getting good tones from the oscillator, do the following. If with the 1222 you are also not getting good behavior from the tuner, don’t waste time on trying to fix that yet. Get good tones on the outputs first — the tuner won…

and

Annotated Simple 1V/Oct Oscillator Stripboard

And here’s the LMNC 3340 stripboard layout, with scribbles: [image] See here for the annotated Simple Low Pass Filter stripboard.

[SpectrumDIY]

Cheers, quite a lot to look through, but I appreciate it!

[SpectrumDIY]

It’s crazy that it works the first time! What the heck XD
Couldn’t think of where to post this as it’s all pretty much the same topic really, but I finished the halloween synth in time!!
I shall have to do a much better job of checking the topics before posting next time. But as this is the last update on the halloween side of things, thought it seemed logical to just put the final piece here and allow it to be totally done.
My apologies that I didn’t put it in the right spot to begin with. Was a bit excited

Anyway.

Here’s what I did for halloween

DIY Halloween Synth