Hearn Morley of Bristol England, manufacture a range of miniature analog audio plug-in modules. These include Voltage controlled oscillators (VCO), Voltage controlled filters (VCF), Voltage controlled envelope generators (ADSR) and Voltage controlled amplifiers (VCA).
Hearn Morley modules
- HM2040 an equivalent of the now obsolete SSM2040 VCF IC.
- HMVCO1c an exponential VCO. The design is adapted from a VCO design by Terry Mikulik published originally in the Electronotes series.
- HMADSR1c a voltage controlled envelope generator.
- HMVCA1b a dual linear voltage controlled amplifier