PORTABELLABZ

The VCS3 Card for 208 / Music Easel
under EMS Cornwall license

The VCS3 Card expands the Music Easel or 208 with original EMS Synthi A and VCS3 circuits :
an oscillator that produces simultaneous square and triangle waveshapes with wide range and features useful modifications (synchronization, shape CV, hi/lo range) and
a noise generator with variable colour, together with my acclaimed
Random voltage generator
modification module that equips many original EMS Synthi A, AKS and VCS3, unlike the 208's one, it's true random.


The
oscillator and noise circuits are powered by +12V/-9V rails as in the original VCS3.
The inputs and outputs voltages are adapted to match the ones used in the 208.

The oscillator tracking is good over about 5 octaves and can be set accurately to 1V/oct, 1.2V/oct or 2V/oct (or other, but who wants that ?).

The VCS3 Card
works fine with 208p, 208r rev2, 208r rev 2.1 and BEMI / Buchla USA Music Easels. It's plug and play.
It works with a 208r rev1 as well if its program card slot is rewired, the modification is straightforward and documented in the build notes.


Because of their weak PSU,
early BEMI Music Easels may not work properly with the VCS3 Card.
A
powered 208 Hub is the easiest solution to connect cards without extra load on the Easel's PSU but is a bit overkill to connect one card only.
Another solution is to add a dedicated PSU inside the Easel, it
is documented in the build notes.

The
VCS3 Card is available pre-built (460 + shipping) or as a DIY PCB set (130 shipped).
The prices include a commission for Robin Wood at EMS, that is the same for each pre-built unit or PCB set sold. 


  Contact me to join the waiting list for a pre-built card or for more information

DIY PCB set (circuit board, front and rear panels) : 130 shipped registered  


Detailed features - Overview by Bill Sequeira - Sound demos

Pics - Users manual - Build notes - BOM - Build thread



Many thanks to Todd Barton for the videos !






More pics
Many thanks to Vanessa Vanderkelen for the pics



Oscillator
- 100% analogue discrete components
- square and triangle outputs, blue bananas are full range outputs for modulation, red knobs are outputs to the mixer
- wide range from very slow LFO to ultrasonic, switchable hi/lo range with fine tuning
- tracking good over about 5 octaves via the 208's keyboard CV in
- variable frequency CV input with attenuverter via black banana
- variable shape CV input with attenuator via black banana
- variable sync input with attenuator via black banana

Noise
- 100% analogue discrete components
- white banana is full range output for modulation
- red knob is output to the mixer
- variable colour

Mixer
- tinijax out to feed the 208's preamp
- banana out for mixed modulation

Random voltage generator
- available on the white banana - a mini slide switch behind the panel selects noise or random,
this affects the white banana only, the noise is still available in the mixer when random is used
- clock input via the 208's inverter "to card" socket
- noise colour changes the random voltage

Rear edge connector
 Wired in parallel with the 208's card slot to plug a second card, it can host any card :
208 ToolBox, BOB expander, iProgram card, Easel Expander, cOC, resistor program card... even a second VCS3 Card.


The PCBs come unpopulated and without parts. I assume no liability for personal injury or damage to equipment or loss of use caused directly or indirectly by the use of these PCBs.
The build should only be performed by those experienced in electronics with access to a good oscilloscope and frequency meter.