Quarterizer

Video signal Amplitude Classifier / 4-input VC switch

The Quarterizer is a four-channel video-rate switch with attenuated individual inputs.  It can be used in quite a few different ways: as a signal amplitude classifier, a complex voltage manipulator, a four-input multiplexer, or as a four-step analog-controlled sequencer.  Four LEDs provide visual feedback to show which input(s) are active.

The Quarterizer is deceptively flexible.  At a functional level it works by selecting one of four independent inputs based on a main control voltage signal input, and connecting that input to the main control voltage output.  Each input has its own attenuator and is normalled to the next lowest input, with the lowest input normalled to a fixed one volt reference.  But knowing how it works doesn't really tell you the full story!

Firstly, if you simply connect the Quarterizer to a voltage input and plug nothing into the individual inputs then the four attenuation knobs let you dial in four different fixed output voltages.  Using a video signal as your main input you then have a four-band image classifier (i.e. one knob sets the output level for each of the black, dark grey, light grey and brightest parts of the image).  If you use a triangle LFO as the main control input then you have a four-channel sequencer, where the LFO output level determines which input is active.

Now, if you also connect the main video signal to the first individual input then it's replicated it across all the other input channels, and you have the ability to separately adjust the level of each brightness band (black, dark, light, bright) of the main video signal, for manipulated brightness and unusual monochrome effects.  With multiple Quarterizers you can adjust each colour of a full RGB video image separately, for infinitely flexible colour manipulation effects.

Finally, if you have several different video patterns available then you can patch each of them to a separate input.  With no main signal input connected to the module the Range knob then acts as a manual control to select between inputs, or otherwise with a video-rate signal as the main input it acts as a four-layer luma hard-keying effect, switching between the individual inputs.

https://www.visiblesignals.net/product/quarterizer/