leeches

they feed on your rack's lights

20 HP

Four soft heads on patch cables. Press one over any light in your rack, a step LED, a drum's flash, a screen, and it drinks: whatever that light is doing becomes a CV, a gate and a sound. Every blinky module you own is a modulation source now, even the ones with no jack.

The LEECHES panel: black, the gold outline of an apothecary jar filling it, four long ringed leeches in bare fibreglass weaving up it between the columns of jacks and knobs. BLOOD 1 to 4 and PULSE along the top, MOUTH 1 to 4 and DRINK at the foot, THIRST a big knob on the spine.

Turn a knob: drag it or tap either side of it, roll the wheel over it or use the arrow keys; a double click puts it back. The leeches are yours: drag one onto any light or a throat, pull it off, let go in the air; or tab to one and use the arrow keys. DRINK is a button to hold. The patches step on by themselves until you touch anything.

A dark loop in B minor and a row of made-up lights. Listen plays the patch from its top.

example patches

Everything LEECHES does here is its engine as designed, running in your browser, the heads a model of the real ones. The lights and the loop are a stand-in rack.

The leeches

A soft black body with a fast photodiode in its mouth and a sticky ring round its lip. Press it on and it seals; pull and it stretches, leaks a little room light, then pops off. It reads what's in its cup: one light, or two if it's between them.

MOUTH 1 to 4: a head on an ordinary patch cable.
THIRST, a big knob and its jack: how little light fills it. At noon a bare LED is full scale; at full a glimmer is, and a head left hanging hears the room.

Every light sings

LEDs are dimmed by flicking them on and off thousands of times a second, and a leech hears that. So every light has its own hidden pitch; dim it and the pitch stays while its colour changes. A light driven by a signal carries the signal: stick a leech on a voice's level LED and hear the voice.

PULSE: the four flickers, DC gone, mixed. Lights faster than the converter fold back down into hearing.

The throats

What a leech drinks climbs its body from MOUTH to BLOOD. Its sixteen cells are the slew itself, and each window shows its own. Blood is dark, so a hungry leech glows, and every swallow is a dark ring going up it.

CLOT, a knob and its jack: how thick the blood is. Fully left BLOOD still carries the flicker; at noon a flash is an envelope; at full it's a swell fifteen seconds long.
BITE, a knob and its jack: BLOOD from straight to a hard gate, and PULSE up to a one-bit square.

Feeding each other

BROOD, a knob and its jack: a full belly stops its own mouth and hands a mouthful to the next leech, 1 to 2 to 3 to 4 and round. So a steady light gulps. A little up, a flash is handed on smaller each time and dies; past three quarters it goes round for ever. In PULSE each belly opens the next one's whine.
A throat is a light too. A head on a window reads that cell, late and upside down. On its own throat, THIRST up, it ticks by itself, slower the nearer the tail. Two across each other's throats are a flip-flop; three in a ring, a clock.

DRINK

DRINK, a lit button and its gate: hold it and all four lights are recorded, up to four seconds. Let go and that length loops, so pull a leech off and the light that's gone keeps going. A quick press spits it out.

What comes out

BLOOD 1 to 4: the top of each throat, 0 to 8 V.
JAW 1 to 4: a gate, shut while there's light in that mouth, with no CLOT in it.
PULSE: audio, ±5 V.

Specs

Format

Width: 20 HP
Controls: 1 big knob, 3 knobs, 1 lit button, 4 heads

Inputs

MOUTH: 1 to 4: a head on a patch cable
CVs: THIRST, CLOT, BITE, BROOD: added to their knobs, 5 V the whole way
DRINK: gate, as the button

Outputs

BLOOD: 1 to 4: CV, 0 to 8 V
JAW: 1 to 4: gate, 5 V
PULSE: audio, ±5 V