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by devinw1
Fri Apr 09, 2021 8:14 pm
Forum: Music Tech DIY
Topic: Holiday week proto: The sequel to B1; B2 Kick Bass module
Replies: 16
Views: 617

Re: Holiday week proto: The sequel to B1; B2 Kick Bass module

So, two things: 1) I am currently putting together a bunch of stuff for Thonk, including some B2 panel/pcb/knob sets, so they will be in stock at Thonk very soon. Also talking with Exploding Shed so they should have it a bit later. 2) I got SMT PBCs in today, with the idea being I can use these for ...
by devinw1
Fri Apr 09, 2021 5:01 pm
Forum: Music Tech DIY
Topic: CMOS Recommendation for Toggling 4 Waveform Outputs
Replies: 6
Views: 143

Re: CMOS Recommendation for Toggling 4 Waveform Outputs

Binary counter, have it reset to 0 when you hit 4. Counter output to 4052 or similar MUX. Bingo bongo!

Oh yeah, and you'll probably definitely want to put some hardware debouncing on that button which will clock the counter!
by devinw1
Fri Apr 09, 2021 11:44 am
Forum: Music Tech DIY
Topic: PROGUE - Analog mono synth - AUDIO DEMO
Replies: 135
Views: 7317

Re: PROGUE - Analog mono synth - AUDIO DEMO

Looking good! Call me crazy but I think gloss white with black silkscreen would be fucking awesome, especially with some nice wood ends.
by devinw1
Thu Apr 08, 2021 11:53 pm
Forum: Music Tech DIY
Topic: R2R duals and quads in THT with decent slew?
Replies: 35
Views: 372

Re: R2R duals and quads in THT with decent slew?

I got to thinking, that a more accurate way to clip at just a bit above +/-5V might be to use a typical clamping situation but use something like BAT43 tied to the +5 and -5 rails. The BAT43 claims 260mV to 330mV Vf at 2mA, so one could set the current limiting resistor at the op amp to get around 2...
by devinw1
Thu Apr 08, 2021 11:31 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

And here is the Iref tweaked to center the CVs better and upped Franco to 560R. I think I'm gonna call this good for now. :guinness: Oh btw in case anyone is wondering about the k value scale change, nothing has physically changed, I am just now reporting the ACTUAL k value (due to a halving that ha...
by devinw1
Thu Apr 08, 2021 11:03 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

Havent been working on this much as I'm freakin' swamped getting stuff together for various vendors for B2, AD110, and Pro2021. Yikes, logistics sucks, but it's all part of the game. Anyway I took some tuning data with the "final" as of right now configuration which is the BMC857 expo and a small 22...
by devinw1
Mon Apr 05, 2021 11:36 am
Forum: Music Tech DIY
Topic: CA3280 spice model?
Replies: 18
Views: 591

Re: CA3280 spice model?

One of the larger differences between the 3280 and the LM13700 is the linearizing diode scheme. Make sure that is correct on the model if you are looking at the 3280 seriously.
by devinw1
Sat Apr 03, 2021 1:03 pm
Forum: Music Tech DIY
Topic: PROGUE - Analog mono synth - AUDIO DEMO
Replies: 135
Views: 7317

Re: PROGUE - Analog mono synth - AUDIO DEMO

Noice!
by devinw1
Fri Apr 02, 2021 3:03 pm
Forum: Music Tech DIY
Topic: Combining 2+ VCOs into a single module
Replies: 9
Views: 331

Re: Combining 2+ VCOs into a single module

Definitely listen to J3RK. I did a simple dual VCO as one of my first modules and it worked great, but I had learned some lessons after having 3340s sync up on my first pass my Pro-One clone PCBs. The 3340s are definitely sensitive to all the layout issues described above (as are most VCO circuits).
by devinw1
Fri Apr 02, 2021 1:43 pm
Forum: Music Tech DIY
Topic: Fatar key (and other tiny broken bits) fix reinforcement
Replies: 6
Views: 119

Re: Fatar key (and other tiny broken bits) fix reinforcement

Ah I see, the UV and and H2O2 must have some kind of action to remove a very thin outer layer (the one that has yellowed). That makes sense, as the newer cars plastic headlights, if they get foggy and yellow, you can easily polish them to look like new with some light polishing compound (or even too...
by devinw1
Fri Apr 02, 2021 12:48 pm
Forum: Music Tech DIY
Topic: Fatar key (and other tiny broken bits) fix reinforcement
Replies: 6
Views: 119

Re: Fatar key (and other tiny broken bits) fix reinforcement

Nice fix, rich! Loves me some 5 minute epoxy for stuff like that. It's super tough stuff.

Kevin, I'm surprised UV helps make them whiter! Usually it is UV itself that makes resins and plastics turn yellow over time, isn't it?!
by devinw1
Fri Apr 02, 2021 11:03 am
Forum: Music Tech DIY
Topic: Something New from Doc Sketchy
Replies: 824
Views: 59636

Re: Something New from Doc Sketchy

I do reckon that's the Dagwood sandwich of Euro modules! Well done! :sb: :sb: Well, there's a lot of circuitry in there! Yes, of course, and I hope you didn't take that as a knock! I always love seeing your creations and have much respect for your artisanal builds! The dome filter layout is indeed ...
by devinw1
Thu Apr 01, 2021 9:55 pm
Forum: Music Tech DIY
Topic: Something New from Doc Sketchy
Replies: 824
Views: 59636

Re: Something New from Doc Sketchy

I do reckon that's the Dagwood sandwich of Euro modules! Well done! :sb: :sb:
by devinw1
Thu Apr 01, 2021 12:44 pm
Forum: Music Tech DIY
Topic: VCF question
Replies: 8
Views: 188

Re: VCF question

That's correct.
by devinw1
Thu Apr 01, 2021 11:36 am
Forum: Music Tech DIY
Topic: VCF question
Replies: 8
Views: 188

Re: VCO question

OK, first, you mean VCF, not VCO. :) So you want 2 independent filters, each with their own exponential control? If so, the chips you mentioned that will not work. If you just need 1 expo control then yes. If you want to make 2 or 4 separate, independent filters using one multiplier chip (and op amp...
by devinw1
Wed Mar 31, 2021 11:35 am
Forum: Music Tech DIY
Topic: Interesting low parts count VCF
Replies: 22
Views: 728

Re: Interesting low parts count VCF

That's pretty cool. I remember reading about that old Russian op amp a long time ago. Pretty cool somebody found a modern chip that can be operated like this. That certainly is dead simple.
by devinw1
Tue Mar 30, 2021 12:51 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

That is interesting. I was just browsing some threads about Prophet 5 and definitely reports of 4051s blowing in them. Looking in the schematics, they don't seem to do anything weird with them. All the pots MUX use them and even have a 1k current limit resistor on the outputs. I wonder what the fail...
by devinw1
Tue Mar 30, 2021 12:10 pm
Forum: Music Tech DIY
Topic: SMT resistor size comparison
Replies: 14
Views: 373

Re: SMT resistor size comparison

0201 and smaller is the devil's work. No human should have to handle these things! lol
by devinw1
Sun Mar 28, 2021 1:20 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

I do remember hearing about this. Is that "why" there's an inhibit pin though? The datasheet just says that INH disables all channels, and I don't see anywhere where it says that you must use this while switching of the chip will be destroyed. It sounds like using the INH pin is more a workaround to...
by devinw1
Sat Mar 27, 2021 11:37 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

Quick question about the 4051: why does it say in the datasheet that it has "logic level conversion" when the "on" (1) levels scale with Vdd? To me, logic level conversion would imply more like how the DG and MUX series work, where there is a local 5V logic level and no matter what Vdd is, your "on"...
by devinw1
Sat Mar 27, 2021 10:54 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

Yes used LM339 quad...I always mix those 2 up! And yeah for sure on the hysteresis. I used a lot... 100k/1M
by devinw1
Sat Mar 27, 2021 8:00 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

Yeah the 4051 is already decoded good point, though I think you'd at least need a transistor for each LEd to have them light 1 per channel and not disrupt the resistor ladder portion, no? Yeah 3 leds works too, though I think communicating in binary on a front panel is a bit off putting to most user...
by devinw1
Sat Mar 27, 2021 6:08 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

That's pretty cool. I would love to get my hands on one of those! I breadboarded the pot octave selector circuit today and it works pretty damn well! There is a nice swath of pot travel between each octave and doesn't feel touchy at all. As expected, I did have to add some hysteresis to the comparat...
by devinw1
Fri Mar 26, 2021 8:40 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 3885

Re: A quadrature triangle VCO

Wow, that seems like a rare bird there! Very very cool. That's encouraging to hear. I was thinking 8 steps on a pot wouldn't be too bad, especially if there are correct hash marks on the panel. Side note, the Proteus1 looks so cool....except that god awful red push button they chose for the preset s...
by devinw1
Fri Mar 26, 2021 5:50 pm
Forum: Music Tech DIY
Topic: The Capille Sistine of the AVRs
Replies: 4
Views: 200

Re: The Capille Sistine of the AVRs

Pretty awesome! Talk about doing more with less!

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