Building the 555-based ADSR envelope generator.

Building the 555-based ADSR envelope generator.

This page comprises the documentation for building the 4HP ADSR envelope generator module - if you can hold the soldering iron at the right end then you can put this together. All the components required to complete the build are through-hole and no surface-mount soldering is required.

All surface-mount components have been pre-soldered - it is up to you to provide the necessary through-hole componentry to complete the build. These are updated boards which have been fabricated by a PCB assembly service - the hand-built modules are now sold out.

The following will be required:

  • 1x 2x5 Eurorack power header - the chevron/line on the rear silkscreen corresponds to -12V
  • 4x Alpha RK097N pots (or compatible) - the attack (ATK1), decay (DEC1) and release (REL1) pots should be 1M audio taper (A1M) and the sustain (SUS1) pot should be 50k or 100k linear taper (B50k or B100k)
  • 1x DailyWell DW-1 (ON-ON) switch - these switches have solder-pin connectors at 2.54mm centres, and the footprint reflects this. Whilst you could fit other types, you'd need to get creative with wiring.
  • 2x PJ301M-12 (aka THONKICONN) jacks (or compatible) - one for the input, one for the output.
  • 1x 3mm LED - I recommend Vishay TLHR4400🔗 LEDs, as they have a voltage drop of only 2V.
  • 4x knobs to suit - one for each pot.
  • Electrolytic and film capacitors with the following values, with a rated voltage of at least 25V unless stated otherwise.
    • C2, C4 - 10uF
    • C6 - 1uF or 2.2uF electrolytic ('long' range decay capacitor - 16V rating is adequate)
    • C5 - 100-330nF film ('short' range decay capacitor; lower capacitance means faster decay)
    • C9, C10 - 10nF film

The schematic is shown below - crossed out components represent items that need to be provided and fitted by you, as listed above (right click + open in new tab to see the full size version)

It should be obvious what goes where - the only real gotchas are the polarities of the electrolytic capacitors (C2, C4 and C6) - look for the small '+' by the component footprint and put the longer lead of the cap through it. Generally, electrolytic capacitors will have the negative side denoted by a vertical band on the capacitor body.

Components can be fitted in any order - generally, though, pots and jacks tend to be fitted last.

 

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