Pneumatic oscillator

Claim 2

A pneumatic oscillator adapted to operate from a supply pressure source to provide variable frequency output pulses in response to control pressure from a variable pressure signal source comprising: first and second bistable fluid amplifiers each having supply input means, first and second output means and first and second control means; switching control means comprising a third bistable fluid amplifier having supply input means, first and second output means and first and second control means; first and second pulse delay means connected between said first and second output means of said switching control means and said first and second control means, respectively, of said first and second bistable fluid amplifiers; means for connecting said second output means of said first bistable fluid amplifier and said first output means of said second bistable fluid amplifiers to said first and second control means, respectively, of said switching control means; and means for connecting said second and first control means of said first and second bistable fluid amplifiers, respectively, to said variable pressure signal source.

Claim 3

The circuitry of claim 1 wherein conditioning circuit means is connected between said control means of said first and second amplifiers and said variable pressure signal source for preventing the control pressure applied to said control means of said first and second fluid amplifiers from dropping below a prescribed minimum value and to provide sufficient control pressure to reduce the frequency of the oscillator to 0 pulses per second when the output pressure of said variable pressure source is at a null value.

Claim 4

The circuitry of claim 2 wherein said conditioning circuit comprises: a first proportional fluid amplifier having first and second control channels and first and second receiver output channels; bias means for applying pressure to said first control channel of said first proportional amplifier; means connecting said second control channel of said first proportional amplifier to said variable pressure signal source; a center output proportional amplifier having first and second control channels and a receiver output channel, said control channels being connected to respective ones of said first and second receiver output channels of said first proportional amplifier; means for connecting said receiver output channel of said center output proportional amplifier to said control means of respective ones of said bistable amplifiers comprising said pneumatic oscillator; and bypass means connected between said receiver output of said center output proportional amplifier and said supply pressure source to prevent control pressure applied to said control means of said first and second bistable amplifiers from decreasing below a predetermined minimum value.

Claim 5

The circuitry of claim 2 and further including output selector means connected in controlled relationship to said variable pressure source, said output selector means including: first and second converter output means, bistable fluid amplifier means having output means, control means and supply input means; means connecting said output means of said bistable fluid amplifier means to respective ones of said converter output means; means for connecting said supply input means of said bistable amplifier in pulse receiving relationship to said oscillator; null pressure selecting means connected in controlling relationship to said control means of said bistable fluid amplifier and in control pressure receiving relationship to said variable pressure signal source for producing output pulses at one of said converter output means when the pressure of said variable pressure signal source is above said null value and at the other of said converter output means when the pressure is below said null value.

Claim 6

The circuitry of claim 4 wherein a first NOR gate is connected between said supply input means of said bistable amplifier means and said oscillator and second and third NOR gates are connected between said output means of said bistable amplifier means and respective ones of said first and second converter output means.

Claim 7

The circuitry of claim 1 and further including first and second converter output ports; output selector means for causing oscillator output pulses to appear at said first converter output port when the pressure of said variable signal means is above a predetermined null value and at said second converter output port when said pressure of said variable signal source is below said null value, means for connecting said output selector circuit in controlled relationship to said variable pressure signal source, and means for connecting said output selector means in pulse receiving relationship to said oscillator.

Claim 8

The oscillator of claim 1 wherein said first and second pulse delay means each comprise a pneumatic R-C circuit.