
"The
HM2040 is an equivalent of the now obsolete SSM2040 voltage controlled filter IC. The HM2040 voltage controlled filter module can be used for all circuit configurations originally designed to use the SSM2040 integrated circuit. The module is housed in a rigid potted enclosure with 0.1" pitch legs spaced 0.7" apart.
Features
* +/-12V* or +/-15V Supplies
* 4 filter sections in one package
* Very low noise
* Low distortion
* Low control feed through
* 10,000 : 1 Sweep range
* Works with any circuit utilizing the (obsolete) SSM2040 IC."

"The HMVCO1d is a 0.7" pitch DIL module providing a temperature compensated accurate exponential voltage controlled oscillator (VCO) intended for audio and synthesizer applications. The design is adapted from a VCO design by Terry Mikulik published originally in the 'Electronotes' series http://electronotes.netfirms.com/
Features
* Wide sweep range 10,000:1
* Excellent logarithmic conformance
* Temperature compensated
* Simultaneous sawtooth, pulse and triangle wave outputs
* PWM Input
* Hard sync input
* +/-12V* to +/-15V power supplies
* Low external parts count.
* Above and below audio frequency operation."

You'll find more details on
Hearn Morley's DIY website including the HMADSR1c ADSR Envelope and the synthesizer pictured here. You might recoginize this synth from the
SDIY UK synth gatherings.