Search found 686 matches

by nigel
Wed Jan 13, 2021 10:01 pm
Forum: Music Tech DIY
Topic: DIY Modular Synth Problem - Voltage between power supply grounds
Replies: 9
Views: 222

Re: DIY Modular Synth Problem - Voltage between power supply grounds

hi jamos, here's the schematic for the power supply I'm working with [...] See this thread . That schematic is incorrect, and does NOT match the circuit on the PCB. On the PCB, one of the AC inputs is connected to 0V, the other to both diodes. If you are trying to drive two of those from a single A...
by nigel
Fri Jan 08, 2021 8:59 am
Forum: Music Tech DIY
Topic: diy partial-kit frustration rant
Replies: 44
Views: 1007

Re: diy partial-kit frustration rant

Reading the parts list to discover these problems is simply one of the new skills that you have to learn when moving from complete kits. (And I don't think that's obvious when you start - I haven't seen any instructions that begin with "make sure you can still find all these bits".) Like any other s...
by nigel
Wed Jan 06, 2021 11:24 pm
Forum: Music Tech DIY
Topic: Patch Cable DIY
Replies: 16
Views: 406

Re: Patch Cable DIY

For me it is a quality thing, a personalisation thing and, as I discovered, also a Zen-like thing as I find making my own cables a good way to empty my mind (which otherwise tends to be very busy more or less 24/7 :mrgreen:). I find making my own cables a good way to fill my mind with rage and frus...
by nigel
Mon Jan 04, 2021 7:18 pm
Forum: Music Tech DIY
Topic: Available depth in portable Eurorack systems ?
Replies: 5
Views: 172

Re: Available depth in portable Eurorack systems ?

My little home brew case is around 95mm deep.
case.jpg
Could be taken to gigs, in theory...
by nigel
Sat Jan 02, 2021 11:54 pm
Forum: Music Tech DIY
Topic: VCO-1 by Thomas Henry - some questions
Replies: 15
Views: 367

Re: VCO-1 by Thomas Henry - some questions

But why not to connect the pots straight to the +-12V of my circuit ? Did you encounter issue connecting the pots straight up to the +-12V ? Because the power supply voltage is not necessarily perfect. In particular, if it is overloaded, then the voltage may drop, or there might be noise or mains h...
by nigel
Sat Jan 02, 2021 9:18 am
Forum: Music Tech DIY
Topic: VCO-1 by Thomas Henry - some questions
Replies: 15
Views: 367

Re: VCO-1 by Thomas Henry - some questions

Thanks for your very detailed answers! A small questions regarding the Tri to Saw circuit above: shall I also add a 1k resistor at the input (in series with the triangle out) of the circuit and also at the Saw output? the BC550 could be replaced with BC547 as well? No (tri to saw) / yes (saw out). ...
by nigel
Fri Jan 01, 2021 8:18 pm
Forum: Music Tech DIY
Topic: VCO-1 by Thomas Henry - some questions
Replies: 15
Views: 367

Re: VCO-1 by Thomas Henry - some questions

As I'm planning to build two of the vco-1 I wanted to know If I can normalised the Sin output of vco1 to the switched lug of both the lin FM input and exp FM input of vco2 and vise versa (vco2 sin out tip lug to exp and lin FM switched lugs of vco1) Can I just solder a wire from the tip lug of the ...
by nigel
Thu Dec 31, 2020 7:05 pm
Forum: Music Tech DIY
Topic: Tremolo sync mod
Replies: 3
Views: 115

Re: Tremolo sync mod

Are you using this as a guitar pedal, or as part of a modular system? If it's a guitar pedal, what kind of trigger are you using? You can't easily convert an arbitrary square wave to a sine without some kind of memory, because you can't tell the frequency phase of a square from its current value. [E...
by nigel
Fri Dec 18, 2020 12:26 am
Forum: Music Tech DIY
Topic: 2164s vs OTAs (13700) what are the differences?
Replies: 26
Views: 509

Re: 2164s vs OTAs (13700) what are the differences?

The main functional difference is that the 2164 has an exponential control response, while the 13700 has a linear response. Other differences - the 13700 chip contains two VCAs, while the 2164 has four VCAs. The 2164 has (I'm fairly sure) lower noise and distortion. The 13700 also has two output buf...
by nigel
Sat Dec 12, 2020 6:14 pm
Forum: Music Tech DIY
Topic: Barton vca and Thomas Henry vca
Replies: 3
Views: 228

Re: Barton vca and Thomas Henry vca

The major difference is the lack of a mixer/buffer on the signal inputs, and the decision to use a 4.7k / 10R resistor divider on the signal input to the 13700. I've built a couple of the Barton VCAs and I always replace these with a 100k / 220R pair instead, to give a more usual input impedance. (I...
by nigel
Sun Dec 06, 2020 4:11 pm
Forum: Music Tech DIY
Topic: Help me understand this Electro Harmonix Schematics
Replies: 19
Views: 487

Re: Help me understand this Electro Harmonix Schematics

The footswitch on my unit has six lugs, and it seems to act/work as a momenraty switch (maybe it's broken, or it has been replaced?). It's a footswitch, so it's designed to be stomped on. If you just push it with your fingers, you might be pushing it hard enough to change the contacts but not enoug...
by nigel
Wed Dec 02, 2020 3:28 pm
Forum: Music Tech DIY
Topic: Info on Euroack physical standards
Replies: 20
Views: 646

Re: Info on Euroack physical standards

Some American makers are doing 4-40 Because it's really important that we don't stick to the few standards that we have. :sarcasm: and it’s so similar you can almost cross thread them. They're so similar that you will cross thread them. Now you need to buy new rails. :bang: Stick to metric, for goo...
by nigel
Sun Nov 29, 2020 7:38 am
Forum: Music Tech DIY
Topic: Best course of action to remove a power connector?
Replies: 21
Views: 563

Re: Best course of action to remove a power connector?

I would try to remove the plastic frame first (either cutting it up with a sharp knife, or getting underneath it and sliding it off the pins), and then desolder the pins one at a time.
by nigel
Fri Nov 27, 2020 5:59 pm
Forum: Music Tech DIY
Topic: The 2020 Show Us Your DIY Builds Thread!
Replies: 519
Views: 45676

Re: The 2020 Show Us Your DIY Builds Thread!

Any chance of getting a schematic? Looks like a lovely delay and has all the features I would want as well. I started doing right angle front panel boards for my DIY builds although I use right angle headers for more mechanical strength. Did you CNC mill the board? I'll have to draw up a clean circ...
by nigel
Fri Nov 27, 2020 2:09 am
Forum: Music Tech DIY
Topic: The 2020 Show Us Your DIY Builds Thread!
Replies: 519
Views: 45676

Re: The 2020 Show Us Your DIY Builds Thread!

My homemade take on the PT2399 delay. I wanted a couple of things: it should be usable both standalone (like a guitar delay pedal), and as a simple signal in, delayed signal out module for building complex patches. It should also have voltage controlled delay (because if it's not voltage controlled,...
by nigel
Tue Nov 24, 2020 10:58 pm
Forum: Music Tech DIY
Topic: Why is it fun to BUILD modular synthesizers?
Replies: 25
Views: 694

Re: Why is it fun to BUILD modular synthesizers?

There is something fantastic about building the circuits that make the wave that makes the sound. This. It's why I first got into computer graphics - writing code is much more fun when you can literally see the results. I enjoy building electronics, the fact that I can then hear the results make it...
by nigel
Mon Nov 16, 2020 6:33 pm
Forum: Music Tech DIY
Topic: garbley noise from as3340
Replies: 3
Views: 111

Re: garbley noise from as3340

At first glance, that seems odd. The 3340 is a triangle core, so if it's the chip that's glitching, you would expect it on the other outputs as well. If it's not the 3340, then you wouldn't expect it to change when you swap the chip. Is there an op amp buffering the triangle output? Maybe it's self-...
by nigel
Sat Nov 14, 2020 7:41 am
Forum: Modular Synth General Discussion
Topic: Polyphonic Theremin (deerhorn like)
Replies: 8
Views: 374

Re: Polyphonic Theremin (deerhorn like)

On doepfer page there is just a patch example where (as i think i understood) you can control the VCA (volume) and then with other antenna you control an LFO ??? why? where the VCO is gonna be? Just to answer this specific point - The oscillator is labelled as an LFO, but the frequency can be adjus...
by nigel
Fri Nov 13, 2020 7:32 pm
Forum: Music Tech DIY
Topic: Look mum no computer VCO with square out and pwm.
Replies: 23
Views: 465

Re: Look mum no computer VCO with square out and pwm.

The CEM is seated correctly and I did hook up positive to position and negative to negative from the power supply. That doesn't quite answer the power supply question. Do you have positive, ground, and negative connections from a power supply providing +12V, 0V, and -12V (three separate terminals)?...
by nigel
Thu Nov 12, 2020 9:43 pm
Forum: Music Tech DIY
Topic: Look mum no computer VCO with square out and pwm.
Replies: 23
Views: 465

Re: LMNC VCO with square out and pwm.

You say 12V, but the circuit needs both +12V and -12V, are you using a bipolar power supply? (Also, it helps a lot if you can either include a schematic, or link to one. Don't assume that everyone knows what circuit you are talking about. If you're asking for help, you should make it as easy as poss...
by nigel
Tue Nov 10, 2020 10:56 pm
Forum: Music Tech DIY
Topic: MFOS 15v supply
Replies: 2
Views: 133

Re: MFOS 15v supply

You might be able to find 16V AC wall warts, I believe they're used for alarm systems or something.
by nigel
Sun Nov 08, 2020 3:26 pm
Forum: Music Tech DIY
Topic: CEM3340 Summing Circuit on Frequency Ctl Pin
Replies: 5
Views: 174

Re: CEM3340 Summing Circuit on Frequency Ctl Pin

If you wanted you could change R4 to 390k, but I would just leave them alone. There should be plenty of range available. Out of curiosity, how are you picking 390? I did nodal analysis on the frequency input pin and didnt quite get what was happening. I assumed that pin 15 was the input to an op am...
by nigel
Sat Nov 07, 2020 11:57 pm
Forum: Music Tech DIY
Topic: CEM3340 Summing Circuit on Frequency Ctl Pin
Replies: 5
Views: 174

Re: CEM3340 Summing Circuit on Frequency Ctl Pin

If you wanted you could change R4 to 390k, but I would just leave them alone. There should be plenty of range available.
by nigel
Sat Nov 07, 2020 1:48 am
Forum: Music Tech DIY
Topic: Digital Tweezers?
Replies: 5
Views: 196

Re: Digital Tweezers?

"Wouldn't work" is a bit strong. Need to be used with care, and probably with an eye on the schematic, yes.
by nigel
Fri Nov 06, 2020 7:16 pm
Forum: Music Tech DIY
Topic: Piezo Sensors vs. Force Sensitive Resistance (differences in coding)
Replies: 3
Views: 113

Re: Piezo Sensors vs. Force Sensitive Resistance (differences in coding)

recently I've been exploring more and more different projects involving sensors. Right now I have a code (which msot of it unfortunately isn't mine) which uses Piezo sensors. For my purposes I've decided to use FSR sensors so the change in the code is required. I would think the most important chan...

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