ER-ADSR-555-01

Eurorack ADSR Module

Features

• Attack-DeCay-Sustain-Release Eurorack ADSR Module
• Takes in Gate signal, generates CV to VCA
• Attack, decay, and release pots control speed
  • Attack, decay, and release times can range from 200ms to 16s
• Sustain pot sets the sustain voltage level
• LED dims to level
• 3U tall, 6 HP wide
• 555 Based design
• Benjie Jiao MiniADSR
  • Original was based on Barry Klein design
  • As built by schmitzbits design - "The Fastest Envelope in the West"
• Benji's build has a three card stack-up and is 4 HP wide
• This card is wider but uses 2 cards

Rev 1 Checkout

• Annotated schematic

• Drive with Erica Synths EDU Sequencer
  • GATE Out output
  • At slowest speed, ~2Hz
• My schematic symbols are Schottky but installed 1N4148 like schmitzbits schemati
• Using 1 M linear pots instead of 2.2M log pots
  • A, D, r pots should have been log pots
  • Controls are are "touchy"
  • Sustain pot is linear as it should be and "works" but is backwards
• ADR series resistors are 220 Ohms but should be 100 Ohms per schmitzbits note
• C3 is 4.7 uF
• Does not have 1M that is dashed line on schmitzbits schemati
• ADSR controls
  • A pot full CW
  • D pot full CW
  • S Pot mid
  • R pot full CW

• Back off Attack just a tiny bit from CCW
• Rounds over the attack like it should but it is very "touchy"

Issues

Rev 1 Issues

• Silkscreen has "DELAY" should be "DECAY"
• Sustain pot backwards
• Cut front side etch 4.7K R10 near left edge of board

• Cut rear side etch 555 U2, at U7-7

• • Add wire R10 left side to Sustain pot, RV3 right side
  • Add wire U2-7 to to Sustain pot, RV3 left side
• 220 Ohms on A, D, R pots s/b 100 Ohms
  • Change R8 to 100 Ohms (A pot)
  • Change R8 to 100 Ohms (D pot)
  • Change R11 to 100 Ohms (R pot)

Assembly Sheet

ER-ADSR-555-01 Rev 1 Assembly Sheet