Search found 1360 matches

by Don T
Wed May 12, 2021 11:03 pm
Forum: Music Tech DIY
Topic: Seriously, what is the solution to the vactrol shortage
Replies: 15
Views: 848

Re: Seriously, what is the solution to the vactrol shortage

since the LEDs are in a feedback loop, i think its R17 that controls the current. in the original buchla schematics this resistor was 4.7k. I am not skilled enough to determine this without loading it into a simulator, the fact that R17 goes to ground confuses me. Looking at the original schematic ...
by Don T
Wed May 12, 2021 6:03 pm
Forum: Music Tech DIY
Topic: Seriously, what is the solution to the vactrol shortage
Replies: 15
Views: 848

Re: Seriously, what is the solution to the vactrol shortage

Thank you. Do you mean R6 which is already 470r? Increase it to shorten long tails, decrease it to lengthen? Screenshot 2021-05-12 115328.png Hmm. In that case, I'd try 220r for R6 to give the trimmer more "wiggle" room. Yes, increase resistance to shorten tails, decrease to lengthen. R6 was origin...
by Don T
Wed May 12, 2021 1:51 pm
Forum: Music Tech DIY
Topic: Seriously, what is the solution to the vactrol shortage
Replies: 15
Views: 848

Re: Seriously, what is the solution to the vactrol shortage

I have a dual Buchla 292 custom build I'm working upon for a client and ordered one Xvive 5C3/2 and one Xvive 5C3/4 and they're very very close to each other and neither is close to anything like the expected ring with a short CV spike. I've tried a 1K multiturn trimpot in series with the + input o...
by Don T
Tue May 11, 2021 8:13 pm
Forum: Music Tech DIY
Topic: Multi-board PCB design tips?
Replies: 20
Views: 397

Re: Multi-board PCB design tips?

My workflow for multi-board projects in KiCad is actually to keep them both in the same project. Use hierarchical sheets to logically separate the schematic per board, then put two outlines in the PCB file. At the very end, I create two copies of the .kicad_pcb file, delete one board from each, and...
by Don T
Tue May 11, 2021 7:51 pm
Forum: Buchla, EMS & Serge
Topic: [4U/LW] Alan & Friends, a take on the Turing Machine
Replies: 56
Views: 4117

Re: [4U/LW] Alan & Friends, a take on the Turing Machine

@synthcube, is the panel that comes with this the size of a standard Buchla single-space panel?
by Don T
Wed Apr 28, 2021 5:11 pm
Forum: Music Tech DIY
Topic: SSI2131 Thread :)
Replies: 13
Views: 323

Re: SSI2131 Thread :)

I think an LFO should have an ignition key and large START button. "Oh... you want me to start now, eh?...." Neil :hihi: Indeed! Maybe I should get key switches, and some of those flip-cover aircraft switches. AND them together, so it requires both to start. :mrgreen: I vote for a large, Dr. Franke...
by Don T
Wed Apr 28, 2021 1:01 pm
Forum: Music Tech DIY
Topic: Why no one made a VCA module with 6AS6/5963 tubes
Replies: 13
Views: 407

Re: Why no one made a VCA module with 6AS6/5963 tubes

Perhaps an analogy which paints this is two flashlights that have bulbs which illuminate a room to the same degree, except that the bulbs are of different designs, one uses a AA battery which is 1.5v and the other uses a square 9v battery which is 9v. One might be smaller than the other, there may ...
by Don T
Tue Apr 27, 2021 7:37 pm
Forum: Music Tech DIY
Topic: Why no one made a VCA module with 6AS6/5963 tubes
Replies: 13
Views: 407

Re: Why no one made a VCA module with 6AS6/5963 tubes

Look into these: 12AC6 12AF6 12BL6 12CN5 12CX6 12CY6 All remote-cutoff pentodes, all work with 12V on the plate, but most can accept up to 24V on the plate. I have a stash of 12U7 and 6GM8 that I am planning on experimenting with in some synth circuits. The 12U7 is a 12AU7 designed for 12V plates, a...
by Don T
Tue Apr 27, 2021 7:29 pm
Forum: Music Tech DIY
Topic: Transistor Based Low Pass Gate schematic?
Replies: 55
Views: 2408

Re: Transistor Based Low Pass Gate schematic?

I was working on the problem, and I came up with what could be a simple and elegant solution. Then Xvive started making vactrols again. I put the project aside. Perhaps I should take it up again, but I need to buy a few parts that I don't have. Is there still a delivery delay from Mouser?
by Don T
Tue Apr 13, 2021 7:37 pm
Forum: Buchla, EMS & Serge
Topic: OG Buchla Easel vs Command: Extra banana patch points
Replies: 8
Views: 496

Re: OG Buchla Easel vs Command: Extra banana patch points

B2080-01A.jpg It looks to me if you want to randomize or otherwise change the step order on the BEMI, BUSA, and clone 208s, you'd have to come up with a completely digital solution for Card 1. Card 1 is an analog sequencer built using CMOS chips, it's not exactly digital in function. Perhaps a card...
by Don T
Tue Apr 13, 2021 3:30 pm
Forum: Music Tech DIY
Topic: Recommend a method to measure Va (early voltage) of PNPs?
Replies: 60
Views: 790

Re: Recommend a method to measure Va (early voltage) of PNPs?

I know a curve tracer is expensive, but would that be the more reliable way to do this?

[EDIT]: Just trying to wrap my head around the problem/point of interest
by Don T
Sat Apr 10, 2021 5:14 pm
Forum: Music Tech DIY
Topic: Build a buchla 208 rev2
Replies: 1073
Views: 92125

Re: Build a buchla 208 rev2

I have a question about my Buchla 208r rev2 that I'm hoping someone can help me out with. I have my tracking set to 1.2v and tracking is good, but when I go up in octaves to around C6, sometimes C5, CO sounds like it is breaking up or modulated by something. This doesn't happen every time which is ...
by Don T
Fri Apr 09, 2021 8:29 pm
Forum: Buchla, EMS & Serge
Topic: Noisebug press release / Buchla future
Replies: 392
Views: 18020

Re: Noisebug "just say no" press release

I would like to point out one thing - Inside almost every student-to-midlevel violin is a label that resembles the below: https://www.the-romantic-school-of-music.com/How_To_Choose_A_Violin/Stradivarius_NOT_.jpg The words "copy of" usually appear in very small type at the top of the label, with a fa...
by Don T
Wed Apr 07, 2021 8:41 pm
Forum: Buchla, EMS & Serge
Topic: The M.E.M.S Project module photos and info
Replies: 33
Views: 1821

Re: The M.E.M.S Project module photos and info

davebr, there have been many times that I have been jealous of your skill, and the things that you have worked on, but this takes it to newer and much higher levels! Congrats!
by Don T
Sun Apr 04, 2021 1:50 pm
Forum: Music Tech DIY
Topic: suggested circuits/pcbs to sum positive CV
Replies: 6
Views: 184

Re: suggested circuits/pcbs to sum positive CV

Almost any basic DC-coupled mixer circuit would work
by Don T
Sat Mar 27, 2021 9:10 pm
Forum: Music Tech DIY
Topic: Korg Poly 61 Problem (Popping/Crackling sounds)
Replies: 3
Views: 129

Re: Korg Poly 61 Problem (Popping/Crackling sounds)

Oh ok didn't thought they can take a damage.. I have clearly corrosion on some leads, I will replace the parts and hopefully it works again then:) Yes, it's pretty insidious. The corrosion can actually creep inside the shell of a chip and damage internal connections. Resistors and caps are especial...
by Don T
Fri Mar 26, 2021 7:11 pm
Forum: Music Tech DIY
Topic: Korg Poly 61 Problem (Popping/Crackling sounds)
Replies: 3
Views: 129

Re: Korg Poly 61 Problem (Popping/Crackling sounds)

If any traces near the battery look discolored, you may need to install jumpers for that trace/connection. If any of the corrosion shows on the lead of a component, replace that component, even if it's a chip.
by Don T
Thu Mar 11, 2021 8:05 pm
Forum: Music Tech DIY
Topic: Buchla 259 Vintage PCB2 grid map
Replies: 6
Views: 229

Re: Buchla 259 Vintage PCB2 grid map

Building a 259 vintage PCB2 is so tedious as you spend all your time searching for the part locations. I finally decided to grid the PCB and make a listing of all the parts. I should have done this years ago as it makes the build go so much faster. I didn't verify it on the entire build so there ma...
by Don T
Fri Mar 05, 2021 3:42 pm
Forum: Music Tech DIY
Topic: Extra eyes on a simple noise/filter circuit?
Replies: 1
Views: 116

Re: Extra eyes on a simple noise/filter circuit?

I look at it this way, the buffering couldn't hurt, may actually help, and if you're going to use a TL084 you have two spare opamps anyway... Seriously, it would depend upon the output impedance of the noise/filter circuit compared to the input impedance of the next stage. That said, a buffer makes ...
by Don T
Wed Mar 03, 2021 7:36 pm
Forum: Music Tech DIY
Topic: Replacing analog pots with digital pots
Replies: 15
Views: 553

Re: Replacing analog pots with digital pots

Why not this: Set up a midi/CV converter for each parameter you want to control, then inside the synth, lift the wiper terminal from the board (or just disconnect the wire if hardwired), then use a passive mixer to combine the two signals, then connect that mixed signal to where the pot's wiper was ...
by Don T
Tue Feb 23, 2021 11:08 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 245
Views: 4599

Re: A quadrature triangle VCO

The real Cadillac solution, which is obviously not probably realistic or pratical, would be to have the effective integrating cap size decrease as the FM index knob is decreased. This would keep the frequency selected by the tuning knobs constant while changing the depth of the FM modulation, and k...
by Don T
Tue Feb 23, 2021 11:00 pm
Forum: Music Tech DIY
Topic: What's the best way to learn how to troubleshoot circuits?
Replies: 25
Views: 814

Re: What's the best way to learn how to troubleshoot circuits?

A book that has been infinitely helpful to me: https://www.amazon.com/Linear-Electronics-John-Linsley-Hood/dp/1882580494/ It explains pretty much how everything works, in a much detail as you want. Another thing that really helps me is building the circuit in this simulator: https://www.falstad.com/...
by Don T
Mon Feb 22, 2021 10:25 pm
Forum: Music Tech DIY
Topic: Buchalish 111 Ring Mod PCBs
Replies: 192
Views: 21319

Re: Re:

and I'm always expanding the documentation section of the historic buchla (100/200 series) pages , with more schematics and notes. Please let me know if you have other information to share! happy wiggling! Grant Richter has uploaded loads of schematics in the Buchla FB group With Grant's permission...
by Don T
Thu Feb 18, 2021 5:18 pm
Forum: Music Tech DIY
Topic: Recapping Korg Mono/Poly question
Replies: 8
Views: 270

Re: Recapping Korg Mono/Poly question

Thanks for the input! My reasoning is that the synth has not been played for the last ~35 years. I assume that some of the capacitors are dried-out. I keep reading about the tantalum caps and I see four of them on the m/p. Can I just replace for regular electrolytic caps? 1. If you know someone wit...

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