Abstract A pulse discriminator for test apparatus called a ball prover including a ball rollable in a pipeline past two axially spaced, spring biased, normally open, momentary contact switches which, when closed, discharge a capacitor, the capacitor having a charging rate lower than its discharging rate to discriminate against pulses which would normally be produced by the bouncing of one or more of the switch contacts. Pulse discrimination may also be achieved through the use of a regenerative amplifier that has hysteresis. Contact bounce would otherwise cause an erroneous total flow reading. A gate control circuit responsive to the voltage across the capacitor operates a gate to pass flowmeter pulses which are counted and indicated. The total of the pulses counted then are directly proportional to the total flow in the pipeline between the times that the switches are closed.
A pulse discrimination circuit comprising: first and second input leads; a switch connected between said leads, said switch having a pair of contacts; first and second resistors; a capacitor, said capacitor and said first resistor being connected in series between said leads; and a D.C. source of potential, said source and said second resistor being connected in series with said capacitor, said first resistor having a smaller resistance than that of said second resistor, closure of said switch causing a pulse to appear across said capacitor, the higher resistance of said second resistor preventing said capacitor from charging at a high rate and subsequently discharging again because of any bounce of said any contact during one single actuation of said switch; and a regenerative amplifier connected across said capacitor, said regenerative amplifier having hysteresis, said regenerative amplifier including a differential Amplifier having inverting and noninverting inputs and an output, and a third resistor connected from the output to the noninverting input of said differential amplifier, a main junction connected to said noninverting input, a fourth resistor connected from said main junction to the junction of said second resistor and said source, a fifth resistor connected from said main junction to said second lead, said second lead being connected to a point of reference potential, said differential amplifier being referenced to said point, and means connecting said inverting input from the junction of said capacitor and said first resistor.
Claim 2
Dependent Claim
238 words
A pulse discrimination circuit comprising: first and second input leads; a switch connected between said leads, said switch having a pair of contacts; first and second resistors; a capacitor, said capacitor and said first resistor being connected in series between said leads; and a D.C. source of potential, said source and said second resistor being connected in series with said capacitor, said first resistor having a smaller resistance than that of said second resistor, closure of said switch causing a pulse to appear across said capacitor, the higher resistance of said second resistor preventing said capacitor from charging at a high rate and subsequently discharging again because of any bounce of said any contact during one single actuation of said switch; and a regenerative amplifier connected across said capacitor, said regenerative amplifier having hysteresis, said regenerative amplifier including a differential Amplifier having inverting and noninverting inputs and an output, and a third resistor connected from the output to the noninverting input of said differential amplifier, a main junction connected to said noninverting input, a fourth resistor connected from said main junction to the junction of said second resistor and said source, a fifth resistor connected from said main junction to said second lead, said second lead being connected to a point of reference potential, said differential amplifier being referenced to said point, and means connecting said inverting input from the junction of said capacitor and said first resistor.
Claim 3
Dependent Claim
14 words
The invention as defined in claim 1, wherein said means includes a sixth resistor.