ER-ADSR-555-01
Contents
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
Schematic
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
Benjie Jiao - DIY Modular Video
Issues
Rev 2 Issues
- Attack works
- Sustain works
- Release works
- Decay noise issue
- Card is sensitive to power supply noise
- (1) +12V Vcc noise
- (2) couples through C5
- (3) to Q3 to TRIG
- Schematic of front end
- Layout
Rev 2 Changes
- Fixed pot ends (swapped ends)
- Added 1M decay resistor "fix" (dashed lines on Schmitz schematic)
- 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
