contralogic released Feldspar, a free vst instrument.
“Feldspar is a VSTi software synthesizer featuring a range of tempo-based modulation options.”
- 16 LFO waveform shapes
- 18 Ring modulator algorithms
- Tempo-synced delay with high and low pass filters in the feedback path
- Simulated oscillator pitch instability for vintage analog style sounds
More info and download here: http://www.contralogic.com/vst-plugins/feldspar/