ER-ADSR-555-01

Eurorack ADSR Module

Features

• 3U tall, 6 HP wide Eurorack module
• Attack-Decay-Sustain-Release 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
• 555 Based design

Credits

• 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

• Ordered wrong (earlier) version of the board
  • Missing 1M decay fix resistor
  • Pots are backwards
• Annotated schematic with Rev 1 reference designators

• Drive IN jack with Erica Synths EDU Sequencer
  • GATE Out output
• My schematic symbols are Schottky but installed 1N4148 like schmitzbits schemati
  • A, D, R need to be log (Type A) pots
• All of the pots are backwards (rework below)
  • A, D, S pots should be CCW for no delay
  • S pot should be CW for full output
• ADR series resistors are 220 Ohms but should be 100 Ohms per schmitzbits note
• Attack overshoots
• May need > 100 ohms
• C3 s/b 1 uF for the pots to have a good range
• Updated Pl for above
• Log pot curves

• Scope capture

Schematics

• Rev 1 Schematic
• Rev 2 Schematic

Issues

Rev 2

• Fixed pot ends (swapped ends)
• Added 1M decay resistor "fix"
• Moved up S, R pots to space them up from jacks
  • Updated controls card and front panel
• Added LEVEL legend to front panel silkscreen
• Re-sequenced reference designators
• Change transistor footprints to offset pins/re-oriented
• Better spacing between parts in upper left of controls card
• Added power supply bypass caps (1 per power pin)
• Added URL, Rev 2 marking to rear of card

Rev 1 Issues

• Silkscreen has "DELAY" should be "DECAY"
• A, D, S, R pots ends are all backwards
• A, D, R pots should be Type A, 1M Ohms (log pots)

Cuts

• Perform cuts before installing parts on card
• Cut at RV1 (pins 2-3) top side

• Cut at RV2 (pins 2-3) bottom side

• Cuts at RV3 (pins 1, 3) top side

• Cuts at RV4 (pins 2-3 and pin 1)

top side

Change Pot Series Resistor Values

• 220 Ohms on A, D, R pots s/b 100 Ohms (PL below is updated already for this)
  • Change R7 to 100 Ohms (A pot)
  • Change R8 to 100 Ohms (D pot)
  • Change R10 to 100 Ohms (R pot)

Add wires

• Add wires to rear of card
• Mirrored images below (back side)
• Add wire RV1-2 to RV1-1 (back side view)

• Add wire RV2-2 to RV2-1 (back side view)

• Add wire R9 left side to Sustain pot, RV3-1
• Add wire U2-7 to Sustain pot, RV3-3

• Add wire D3-K to RV4-3 (back side view)
• Add wire RV4-1 to RV4-2 (back side view)

Add Release Resistor

• Add 1M resistor top side of card

Assembly Sheet

ER-ADSR-555-01 Rev 1 Assembly Sheet