Tag Archives: PCB

“Arch” 424 VCO

"Arch" 424 Eurorack VCO
“Arch” 424 Eurorack VCO

Single VCO with multiple waveforms


“Arch” 424 is a voltage-controlled oscillator. This VCO’s frequency range is wide, Can be used as VCLFO. It can produce four waveforms simultaneously: square, sawtooth, triangle, PWM and sine wave (sawtooth shape is not perfect yet). The frequency or pitch of the VCO is determined by tuning (Pitch and Fine) knob, and by the voltage present at the CV inputs.
You can control the pulse width of the square wave either by hand, or by voltage control – Pulse Width Modulation or PWM.

If perfect pitch is required better VCO is recommended. For a perfect sawtooth this is not recommended.

Part of the Synthesizer Modular


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Ninjani Bassline

Video of first test of ”Ninjani Bassline” back in 2008.

Why I posted this now is because I just dug it up again and dusted it off, then decided to finally finish building it. So you can expect new pictures and maybe a new video of the finished synth soon.

What needs to be done is merely cosmetic, knobs , panel layout and minor final fine tuning adjustments.

“Ninjani Bassline” is a essential sequential analog synthesizer I built in 2008. It has a VCO, 2 AR Envelopes, VCF, VCA and a 16 step sequencer.

1 x VCO -Voltage controlled oscillator – OTA. Square and sawtooth wave.
1 x VCF – Voltage controlled filter – Sallen Key, Korg MS-20 type clone. Low-pass & High-pass.
2 x EG – Envelope generator – Basic envelope attack and release.
1 x VCA – Voltage controlled Amplifier – OTA Based.
1x Sequencer – “16 steps VCO pitch” or “8 steps VCO pitch and VCF cutoff”