RAS Virtual Collection is a free collection of five synthesizers of the RAS Vintage collection that includes RA Mowg, Oddy-Free, Prophanity, Mini-Vyn, TerVoxSyn. They are available for download in one package, free of charge. If you are looking emulation of Moog Minimoog Model D, Arp Odyssey Mk.II, Sequential Circuits Prophet 5 or a Theremin, they’re worth trying.
Dexed is a free multi platform, multi format VST plugin synthesizer instrument that is closely modeled on the Yamaha DX7. Under the hood, it uses music-synthesizer-for-android for the synth engine and JUCE as a plugin wrapper.
Kx-PolyM-CSE is a free vintage modular polyphonic synthesizer VST instrument with CV/GATE sequencer and CS70M* emulation.
Vinyl — is a free VST effect for Windows that emulates the sounds of old vinyl players. Vinyl recreates the dust noise and frequency response of old recordings. You can adjust intensity, color and amount of dust noise in a wide range. Also you can simple select the age of vinyl discs.