Search found 71 matches

by homeless_peep
Wed Oct 18, 2017 2:11 pm
Forum: Modular Synth General Discussion
Topic: my first module...having trouble keeping things in tune
Replies: 23
Views: 1126

As a sidenote, there is a high chance that the dreadbox osc doesn't include any HF compensation or it's not configurable. I'd aim for 5 solid octaves, for starters. The soft synth idea is good if you want a good, in tune reference. Since you want to complement the brute, it'll be best to use that as...
by homeless_peep
Wed Oct 18, 2017 9:48 am
Forum: Modular Synth General Discussion
Topic: my first module...having trouble keeping things in tune
Replies: 23
Views: 1126

Supply voltage should not make much of a difference to tracking, since the expo converter is a differential input circuit. Try the tracking at mid-low frequencies, around 440Hz. Each osc should be reasonable within V/oct specs, ie you should have almost perfect tracking. The higher frequency trackin...
by homeless_peep
Fri Sep 01, 2017 4:02 am
Forum: Music Tech DIY
Topic: Are exponential convertors interchangeable?
Replies: 5
Views: 1069

From what I've seen, there are really few options for the exponentiating core. Almost all circuits use the standard configuration, with changes in bits before or after that (voltage scaling, temp compensation, high frequency trimming). Another consideration is the maximum current acceptable by the V...
by homeless_peep
Wed Aug 30, 2017 8:25 pm
Forum: Music Tech DIY
Topic: Understanding stabilization capacitors
Replies: 22
Views: 1609

nice, loved the plots.
A simulated bode plot would be good too. Maybe for a next article?
by homeless_peep
Wed Aug 02, 2017 12:26 pm
Forum: Modular Synth General Discussion
Topic: Mutable Instruments CVPal
Replies: 198
Views: 49790

One could build a hardware MIDI interface and rewrite the firmware on the chip to work with it, but it would pretty much be designing a new module, not a "mod" of this one. That's what I have in mind. There are pads on the PCB, so I can fit an optocoupler for the midi interface. I was hop...
by homeless_peep
Wed Aug 02, 2017 11:06 am
Forum: Modular Synth General Discussion
Topic: Mutable Instruments CVPal
Replies: 198
Views: 49790

I'd like to consider a CV pal for two voice operation, but I'm sceptical because of the whole latency thing. I'm on windows 7 ultimate. I wonder, is there a way to mod this in order to receive midi data through the usual 3 pin midi interface? I can sure fit a 3.5mm stereo jack there. Would that impr...
by homeless_peep
Wed Aug 02, 2017 7:44 am
Forum: Music Tech DIY
Topic: reverse engineering the IR3109
Replies: 107
Views: 37656

more like the general method you used to reverse engineer the topologies. For example, finding the MOS stages, the expo converter topology and so on. Outlining the process for one portion (of your choice) should get the message across.
by homeless_peep
Wed Aug 02, 2017 4:08 am
Forum: Music Tech DIY
Topic: sinusoidal wavefolder
Replies: 123
Views: 19119

the second D. pair is available in the package anyway, so I just went on and used it. However, you're right, and it can serve as the thermal oven for the saturating part instead.
by homeless_peep
Tue Aug 01, 2017 8:43 pm
Forum: 1U & 3U Eurorack Modules
Topic: Need a bigger case, making your own, cost effective?
Replies: 14
Views: 1125

Most places that sell wood planks can cut them for you to the appropriate size. Unless you want some "fancy" shape, like the last post, making a wooden box is not that hard. What you need to keep in mind: Measurements have to be precisely calculated and weel though; you don't want your rac...
by homeless_peep
Tue Aug 01, 2017 8:29 pm
Forum: Music Tech DIY
Topic: reverse engineering the IR3109
Replies: 107
Views: 37656

Wow, this is fascinating work.
How did you work to reach those conclusions?
by homeless_peep
Tue Aug 01, 2017 8:09 pm
Forum: Music Tech DIY
Topic: Practical 1V/Oct CV range from Sequencer to VCO
Replies: 7
Views: 767

As mentioned, pitch is calculated as a "displacement" from a "root" frequency. You can tune a VCO for "any" frequency at 0V, let's say 100Hz. 0V gives 100Hz, 1V 200Hz, 2V 400Hz and so on. If 0V ->50Hz then 1V->100Hz and so on. In that sense you don't need negative (or p...
by homeless_peep
Tue Aug 01, 2017 7:54 pm
Forum: Music Tech DIY
Topic: sinusoidal wavefolder
Replies: 123
Views: 19119

I actually forgot to upload the transistor version. Here it is, along with the simulation result and a true sinewave of comparable amplitude, as a reference.
by homeless_peep
Tue Aug 01, 2017 7:52 pm
Forum: Music Tech DIY
Topic: sinusoidal wavefolder
Replies: 123
Views: 19119

the OTA one looks like its working well. the transistor one sounds like a discrete OTA version and not the barrie gilbert implementation? exactly. It implements the exact same functions as the OTA circuit, but skips the whole current mirror part (inside the IC, in order to obtain a current output)....
by homeless_peep
Tue Aug 01, 2017 7:36 pm
Forum: Music Tech DIY
Topic: PCB layout - current least frustrating tool?
Replies: 51
Views: 5353

I use eagle most of the time and have grown used to it's quirks. Most engineering software has horrible user interface/experience for some reason (Orcad, ADS, Eagle, KiCad, Autocad, they are all a pain in the ass), you just have to pick what fits your requirements and style. KiCad has a very flexibl...
by homeless_peep
Mon Jul 31, 2017 2:39 pm
Forum: Music Tech DIY
Topic: Klangorium/CMOS board with Eurorack questions.
Replies: 3
Views: 533

CMOS logic can run at up to 20V (Vdd-Vss), so 12V should not damage them. There might be other sensitive ICs though, so check the maximum ratings of each one. Unless there is some kind of ouput stage (lowering the 0-9V pulses to something else) you might need to include that. The eurorack standard, ...
by homeless_peep
Mon Jul 31, 2017 1:53 pm
Forum: Music Tech DIY
Topic: question about supplying power to a synth
Replies: 25
Views: 2779

Most regulator ICs include overcurrent protection, to save the IC from self damage (put place your bets on "it will be fried" if you short circuit them). The case of modular systems is slightly peculiar because the supply designer cannot know what constitutes a short circuit and what is ju...
by homeless_peep
Mon Jul 31, 2017 6:20 am
Forum: Music Tech DIY
Topic: sinusoidal wavefolder
Replies: 123
Views: 19119

thanks for reporting your experience, its great to hear someone built it up. the overdrive on it is pretty good. did you use 2 x LM3046? no. 3 of the trannies make up he non linear stage and he other two make a voltage adder. i then used a differential opamp stage to convert the output to single en...
by homeless_peep
Mon Jul 31, 2017 6:06 am
Forum: Music Tech DIY
Topic: Grounded pot makes pitch jump... What is going on?
Replies: 12
Views: 699

use a switched jack (normalled to GND). When he input is just floating, it picks up noise and it's potential changes from things like you being close to it or touchig it and so on. using x1 mode on the oscilloscope places a high impedance between that point and ground, which is enough to ground that...
by homeless_peep
Sun Jul 30, 2017 8:39 am
Forum: Music Tech DIY
Topic: The Power Module!
Replies: 6
Views: 1356

might be worth replacig bare leads wih insulated/heatshrunk cables, just for safety and peace of mind.
by homeless_peep
Sun Jul 30, 2017 8:34 am
Forum: Music Tech DIY
Topic: sinusoidal wavefolder
Replies: 123
Views: 19119

That looks neat! I based my triangle to sinewave converter on that paper of yours,and even designed a (non optimised) version using the lm3046 bjt array. I experimented with folding using opamps and diode clipping (not a sinewave shape) on a guitar pedal and the sound is very distinct. distorted but...
by homeless_peep
Sun Jul 30, 2017 7:55 am
Forum: 1U & 3U Eurorack Modules
Topic: Design and build a module?
Replies: 52
Views: 4544

it may sound harsh, but there is no shortcut in this. you don't need to spend 5 years in an EE program to do it, but you still need to invest money and time (especially time) in order to understand electronics and signals (and a whole lot of other things) in order to reach that point where you trans...
by homeless_peep
Sun Jul 30, 2017 7:25 am
Forum: 1U & 3U Eurorack Modules
Topic: Bench Power supply, would this work?
Replies: 7
Views: 1391

bench PSUs are suited for lab purposes, ie setting a range of different voltages, current limiting (or constant current mode) and supplying a rather big amount of power (3A 32V per channel is not rare). however, i do have doubts when it comes to ripple and noise, because all of hose perks are accomp...
by homeless_peep
Tue Jul 11, 2017 5:00 am
Forum: Music Tech DIY
Topic: Boost converters, considerations for *local onboard* +/-15V
Replies: 16
Views: 1351

May I ask, why do you need those extra 3V?Unless it's essential for your application, your efforts might be more efficiently spent in making the module work with 12V rather than design a really good switching regulator on board an analog sound PCB.
by homeless_peep
Fri Jun 09, 2017 1:45 pm
Forum: Music Tech DIY
Topic: Refer me to a few "non standard" waveshapers
Replies: 8
Views: 738

Actually, it just occured to me. I haven't included any kind of voltage quantizer (other than the 2 state one, ie the comparator).

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