Thanks! What about the 100k trimpot at the top left? I could not find anything hints on https://www.skullandcircuits.com/vcf-3/
The trimpot is used to set the filter cutoff offset (= it adjusts how low the filter cutoff frequency can be)
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I add a vactrol CV IN with Attenuator on the Unbalance pot, and during the process of calibrate, i made some change :
replace the *33K by a 47K trimpot
and change the volume pot OUT by an Attenuator
I found i have better result like this.
Photos and short demo here 
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Dual Balter Gate Delay from NLC
Pics, schem, video …
DUCKING SIDE CHAIN original schem from Juanito Moore
Pics & demo video of my build here
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Hello!
This is a fairly simple clock module I designed with some built in division. As it’s only used for tempo rather than audio frequencies it was more useful to me to have the divisions marked in as relative note durations rather than f/1, f/2 etc, but you can always relabel. The slowest division (“whole note”) goes from about 16 to 170 bpm. I didn’t explicitly include the LED and jack wiring for each division for simplicity as it’s just a repetition of the one shown plus it’s all there in the schematic. The stripboard layout is very slightly different to the actual one soldered up below as I moved some caps closer to the op-amp in the layout in response to feedback. Also had to make room for a comedy-sized 2W resistor I purchased in error and didn’t want to waste…
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Nice!
I may be mistaken, but looking a bit closer at the design I think you could have used 2 diodes (one from the switch to MR and the other from output Q5 to MR) to reset the clock instead of using U3a, Q1 and Q2.
Furthermore U3a could then be used as the oscillator and then you wouldn’t need U1a and U1b.
That would simplify the schematic quite a bit.
EDIT: here is a draft of what I had in mind.
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Hi Jos,
That’s a good 2 chip solution! I’d just bolted together some circuit motifs I knew worked and went for a transistor OR gate as I was out of CMOS gates. Previous projects of mine have been based on logic gates/Z80 so it hadn’t occurred to me to use diodes. You learn something new every day!
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Hello folks,
share my created stripboard layout, MSK 011 from “north coast synthesis”!
The module is also available to buy ready-made for around 160 €. It is “Open Source” Schematics and KiCad data are freely available at: MSK 011 Transistor Mixer - North Coast Synthesis Ltd.
It is a discreate transistor circuit, perhaps comparable to the “Moog CP3”!
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I made a layout for the s&c LFO using a TL074 instead of the two TL072 in the Schematic.
I only used the Tri and Sqr outputs, I think this is all i need for now, but there is space to add the other Waveforms to the Circuit.
a nice querk of this circuit is that negative CV can stop the LFO from oscillating.
I built this today and it works as intended.
I used 1M for both of the pots
Pots are facing up.
Schematics: https://www.skullandcircuits.com/lfo-1/
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Hmm, they invert the sin output and call it “cos”.
I wish quadrature were really that easy…
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Today I did the Vintage Linear VCA from electric druid.
I put a few resistors in series since i did not have the right values at hand,
I also added a trimpot, feeding some negative voltage into the CV-mixer via a 1.5M resistor, to cancel out unwanted offset.
The pots are 100k linears facing up.
the Lm13700 has 2 VCAs in it so you could make this a double VCA, but i was too lazy to do so.
Schematics:Design a Eurorack “Vintage VCA” with the LM13700 – Electric Druid
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A little advice if I can, would be to add the name of the module to your presentation and also the source.
Because if someone finds the image after a search on the web, and saves it, they won’t necessarily have the information you put in your post on this forum.
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of course you can. i will do so in the future.
Oh man i must have a thousand schematics on my phone that i screenshotted and forgot what they are
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Here is a crappy layout for a crappy drum machine. Was going to build one with all 8 sounds but because this is too crappy I stop here. No further drum machines for me.
Some notes:
- The trigger is crap, it ties notes together and causes the woodblock to click twice.
- The outputs clip when pots are at maximum.
- Troubleshooting is a hell.
- The sequencer ticking leaks a bit.
But anyways it sounds cool, especially with hard clipping from 1n914 diodes.
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Have you some sounds of it ?
Quick demo going through stuff the machine can do:
First some normal sounds
Diodes on off on off
Some Woodblock sounds
Bassdrum lengths
Some simple jamming
With distortion
All kinds of crap and oscillation at end
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