Free Modular

Envelope Assembly Instructions

See general assembly instructions

Components

Most parts are available on Tayda (cart link, quick-order CSV).

See general components notes for more info about acquiring parts.

Interactive BOM: front, back

  Board Reference Part Value Source Comment
  Front R1, R3, R5, R7 Resistor 100kΩ Tayda  
  Front R2, R4, R6, R8 Resistor 200kΩ Tayda  
  Front R9-R12 Resistor 2kΩ Tayda Should be 1/5 potentiometer values. If you are using 50kΩ pots, use 10kΩ resistors here.
  Back R13-R20 Resistor 100kΩ    
  Back R20-R24 Resistor 10kΩ Tayda Determines LED brightness. Any value between 220Ω-10kΩ might be appropriate depending on which LEDs you have and how bright you want them. Lower resistance values mean more current and brighter LEDs.
  Front R25, R26 Resistor Tayda Determines output impedance
  Front RV1-RV4 Potentiometer B10kΩ Tayda, Thonk Linear. A larger value is fine, although if the value is too large the response curve might be a little warped. Make sure to match R9-R12 accordingly.
🔴 Front SW1 Button TL1105SP (e.g. TL1105SPF250Q) + 1RBLK DigiKey (switch), DigiKey (cap) The caps for these switches need to be purchased separately. The caps I use are #1RBLK. The switches are available in different actuation forces and materials, so the last part of the part number might be a little different. Sometimes, the switches and caps will be sold together and the cap number is appended to the end of the part number. If you don’t want to use these specific switches, any “6mm tactile switch” with a standard 4.5mm x 6.5mm mounting pattern like this one should work here. Those are a bit narrower, though, so you might want to adjust the faceplate accordingly.
  Front J1-J8 3.5mm Jack THONKICONN (a.k.a PJ398SM or PJ301M-12) Tayda, Thonk  
  Front D1-D11 LED 3mm Tayda My design uses 4 colors (amber, blue, red, green) to match the 4 knob colors, but obviously use whatever colors you want. Different colors might have slightly different brightnesses so you could tune R20-R24 to make them uniform.
  Back Q1, Q2 Transistor 2N3904 Tayda, DigiKey  
🔴 Back U1 DAC MCP4922-E/P DigiKey  
  Back U2 Op-amp MCP6004 Tayda, DigiKey  
  Back C1 Capacitor 10uF Tayda Power supply noise filtering capacitor
  Back C2, C3 Capacitor 100nF Tayda Power supply noise filtering capacitor
  Back A1 Arduino Nano v3.0 Tayda  
  Both J10-J12 Pin headers 1x7, 1x8 Tayda (Male, Female), Amazon Solder the two boards directly together using the male headers or make them detachable using a male/female pair (recommended).
  Back J13 IDC connector 2x8   Eurorack power header. Can use two rows of male pin headers or a shrouded connector (recommended).
  Back J14 Configuration Jumper   Tayda See Configuration

🔴 = Missing from Tayda BOM

Configuration

The module has 3 pairs of holes on the reverse side of the back panel (J14). By bridging each pair (either by soldering a wire through both of them or by soldering on pins and using removable jumpers) you can effect the behavior of the module.

Jumpers 1 and 2 control the behavior of the “Aux” output

Pair 1 Pair 2 Aux behavior
Open Open End-of-rise gate: Will go high (5v) as soon as the attack stage ends, and will stay high until the cycle ends (output goes to 0) or returns to attack (if the envelope gets re-triggered)
Bridged Open End-of-fall gate: Will go high at end-of-cycle (after release) and will go low again as soon as the next cycle starts (or after the attack stage in ACRC Loop mode)
Open Bridged Non-zero gate: Will go high for the duration of the cycle (as long as the envelope is outputting a positive value)
Bridged Bridged Gate-follower: Will duplicate the Gate input

Config jumper 3 is not currently used. If there is any behavior of the envelope that you would like to be able to customize, let me know!