Fives is a collection of modules based on the specified physical operation of the world's most popular integrated circuit: the LM555 multimode timer.
The 555 isn't generally used as an oscillator in modular instruments because, while it can easily run in astable mode and generate a clean square wave with a variable duty cycle, varying the frequency without changing the duty cycle requires a variable capacitor, which are expensive and hard to integrate.
There is, of course, no such limitation in the world of VCVRack; variable caps are free and never break down, and voltage-controlled variable capacitors are just as easy.
So, Fives provides modules that closely model what a real 555-based module would look like as well as modules that apply the power of CV and impossibly accurate and fast variable capacitors to the same mathematical model.
Fives Astable is a low-frequency oscillator and clock generator based on a physical model of the LM555 timer chip in an astable configuration. It has two knobs - ON and OFF - which control the high and low time of the oscillator, and a RESET input which, when above 5 volts, kills the output.
The total period of oscillation is the on time plus the off time; there is no single frequency control. It can oscillate as quickly as 9 Hz and as slowly as 0.1Hz (once every 10 seconds) with a duty cycle around 66%.
The UNI/BI toggle transposes the waveform from 0v to 10v (default) to -5v to 5v (BI mode).
The Fives Astable C is a voltage-controlled audio-rate oscillator which extends the slimmer, simpler Fives Astable with a variable capacitor and CV inputs for the ON, OFF, and PERIOD inputs. The added PERIOD variable capacitor allows the Fives Astable C to oscillate as quickly as 2.6 kHz or as slowly as 26 Hz, with a duty cycle as low as 56.5%.
It is tuned to take 1V/Oct input on the PERIOD input by default, with all parameter knobs at 33.3%. Modifying any of the parameters will detune the module, but that can be fun too.
CV applied to the inputs are scaled by the knob parameters.