XR22 VCO FT - VCO with Amplitude Modulation and FSK - Minijack Version

VCO with amplitude modulation input and FSK (Frequency Shift Keying)

The XR22 VCO FT is a VCO with amplitude modulation option, which can be used for volume control or ring modulation of the oscillator's sine/triangle output. The AM-input signal is added to a DC-voltage adjustable by knob 'Gain' (between ca. +/-5V) and the sum voltage is being internally multiplied with the sinewave/trianglewave. The result is an oscillator amplitude depending on the 'Gain'-DC plus AM-input signal. The applied AM-input signal can be mixed to the VCO output signal (modulated or unmodulated) too - a kind of 'dry/wet' control with the mix provided on the sine/triangle output. With no AM-input, the XR22 VCO FT behaves like a normal sinewave/triangle VCO, then its volume is controlled by knob 'Gain'. Whereas with the knob 'Gain' in center position, the oscillator tone is becoming almost muted, and the input signal on 'AM in' controls the amplitude of the wave completely; thus the VCO can be used as a ring modulator.

The FSK (frequency shift keying) option provides two internally switchable different oscillator frequencies F1 and F2; each controllable by the two big-sized knobs (and their respective fine-tuning knobs and CV inputs). Switching between F1 and F2 can be done manually or by a logic signal (e.g. a gate signal) applied on input 'FSK in'.
Further, it is possible to use the XR22 VCO FT's squarewave output for FSK switching. This will result in ramp or sawtooth (on the sine/triangle output) and pulse (on the squarewave output) waveforms. The falling and rising edges of the of the sine/triangle signal and the duty-cycle of the squarewave output are independently adjustable, and/or controllable via CVs of F1 and F2.
Furthermore, there is a switch for linking F1 to F2. In this case, the ratio between F1 and F2 is remaining the same, independently from the frequency, and ensuring properly 1V/oct. CV tracking.
A switch allowes to enable 'sync mode': An applied trigger will restart the wave always at the same point, useful for synced LFO applications and more.
For optical control, the XR22VCO FT has a full-color LED for AM visualization and a 2-color LED for FSK control.

• Amplitude modulation (AM) input
  - Ring modulation
  - CV controllable volume of the sine/triangle output
  - Advanced waveform shaping (via e.g. feedback)
• FSK (frequency shift keying)
  - Pulse and ramp waveforms generation
  - Switching between 2 different frequency CVs (with gate signal)
  - Advanced waveform generation
• Switchable Sync-Mode
• Full-Color LED for AM visualization