#340

Could someone hint me to an easily EU available equivalent to an LM324NG quad opamp for my echo matic?
https://easyeda.com/MattDGTL/echo-matic-new

Should other Versions of that chip work just fine?

#341

The pin outs for quad op-amps seem to be the same.
Any other LM324 op-amp will certainly be pin compatible. The LM324NG is now obsolete and I’d try replacing it with a LM324N, which is available from any electronic components supplier for about €0.50.

1 Like
#342

Any advice for using this circuit to drive a spring reverb tank instead a tape?
Maybe changing out resistor or sth. The tank should be 800 ohms

#343

Anybody around here have experience building midi capable solenoid drumming devices?

#344

I use a ring binder with pokemon card sleeve thingys for my resistors. Has been really good thus far :+1:t2:

2 Likes
#345

Does anyone have experience with DC motors?

I’m thinking about adding a simple/compact motor to my arc turntable thing:
ae3ad5e590a44986c21a51eb7ca81991107b5437_2_666x500

Where rather than using the delta values and virtualizing “movement” once you stop touching the platter (so when you stop moving, the playback continues as normal), I would instead have a small DC motor that’s coupled to the underside of the printed part:
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Conceptually that kind of makes sense to me, I just have very little experience with DC motors.

The arc knob is pretty light so it doesn’t need to be too powerful, I’m just thinking that when you touch the record to “stop” it, that it would either have to start letting the belt underneath start slipping (so something that has some give to it (rope/string?)) OR having a DC motor that doesn’t mind getting physically stopped.

Anyone have any thoughts for this kind of thing?

2 Likes
#346

Anyone a recomendation for a small pcb but nice display Oscilloscope?

1 Like
#347

If you want cheap and functioning but not super accurate search DSO138 DIY Digital Oscilloscope Unassembled Kit on Banggood.com $24.11 includes enclosure and all parts, not bad.

#348

Does anyone have a link to some resources to get started DIY with eurorack. I’ve built many guitar pedals, designed PCBs with Eagle, and order and source parts for guitar effects.

I’m not sure where to start with euro, I feel like I need a parts library for Eagle for the eurorack specific parts, like the power header.

I was also looking KiCAD. I’m willing to start by learning that if there’s more resources there.

1 Like
#349

4ms has a Kicad parts collection on their github, and Music Thing Modular has an Eagle parts collection: https://github.com/TomWhitwell/MTM-Parts-Library

All of the Mutable Instruments designs are open source and eagle files are available here: https://github.com/pichenettes/eurorack

Also Music Thing Modular has open source Eagle designs: https://github.com/TomWhitwell

Power headers in Eurorack are just standard size 10-pin or 16-pin headers.

Depending on your level of electronics knowledge, it might be useful to look at the (incomplete) circuits on the Doepfer DIY page: http://www.doepfer.de/DIY/a100_diy. If you didn’t already know, Doepfer is the originator or the Eurorack format.

These are also relevant:
http://www.doepfer.de/a100_man/a100t_e.htm
http://www.doepfer.de/a100_man/a100m_e.htm

3 Likes
#350

I have a few Buchla panel / PCB sets that it’s finally time to start building. As I review the BOM, it looks like the recommended source for VTL5C3 vactrols (Smallbear) no longer carries them. They do have a “workalike” which would probably suffice, but I figured I’d ask around first. Anyplace good to pick up vactrols these days?

1 Like
#351

SynthCube carries a decent selection of vactrols.

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#352

Thonk have them, as do Aliexpress, Aliexpress delivery wait times are super long though. If you want to take advantage of the cheap prices there order well in advance.

1 Like
#353

Those prices are low enough to make me leery… $1/pc falls into “too good to be true”.

#354

I think most, if not all, of the normal synth parts retailers are selling the same xvive "workalike"s. I’ve used them without issue. It’s not very elegant but you can always socket them, too, of course if you suspect they are not direct replacements for what you need. Or just go xvive and never look back!!

1 Like
#355

I have ordered spacers, m3 screws, m2.5 screws, vactrols, IC’s etc without a problem. They turn up eventually… Think my vactrols cost more than $1 though.

It is nice to use xvive though and as @addamm says, socketing them is a good idea.

2 Likes
#356

I like the xvive but I’ve also used the one small bear has. The xvive ones seem tighter but they’re both in the same ballpark really. I put on xvives to modify my hexmix (that’s a whole other story) and I was hoping to get the vactrols replaced with the newer xvives because you know, new tighter tolerance all that jazz. There was literally no real difference. I feel like when completely on I got a slightly lower resistance with the xvives than the others but there really wasn’t much difference - we’re talking less than 1k ohm of difference. The off resistances were more less the same coming in around 1Mohm. Between the xvives I had a decent amount of variance from one vactrol to the other so I ended up ordering 10 and testing/measuring to put in 6 a tightly matched as I could.

CabinTech Global is where I typically source vactrols but were sold out a month ago - they might’ve restocked by now. Best price I’ve found for small quantities is there but the small bear ones should work if you’re ready to get after this project.

2 Likes
#357

as mentioned, the MTM-Parts-Library from @TomWhitwell has a good number of things in it (including a variety of power header parts, IIRC), but it’s a standard 2x08 or 2x05, 2.54mm pitch header that’s already got many versions in the EAGLE standard library. Making your own part, with preferred silking, is a fun rite of passage for Euro EAGLErs.

beyond that: if you can make a pedal, you can make a module. I strongly recommend looking at the schematics for modules that are open source - in particular, Tom’s MTM stuff, Emilie’s work; there’s a lot of belt/braces in them with regard to input/output impedances and power regulation/protection, but beyond that, it’s just… audio electronics? Can you say more about what’s blocking you?

#358

maybe not the answer you’re looking for, but you can DIY a vactrol/optocoupler pretty easily. it can even be fun if you’re interested in playing around with the response curves of the LED/LDR. the vactrols in buchla 227e were “from scratch” in my day, complete with little isolation boxes glued over each component pair, and a (IMHO) compellingly organic and subtle diversity in the exact panning / saturation behaviors per channel / unit. (actually IIRC one motivation for this was to have a little more hands-on control given the observed variance in our new-old stock of “integrated” vactrols.)

9 Likes
#359

The more I’ve thought about this the more I love the idea, and I will absolutely be building some of these. Thank you!