Abstract The present disclosure provides a novel integrator circuit including an operational amplifier having first and second input terminals, said first input terminal being adapted for connection to a voltage source and including a resistor between said source and terminal. A first negative feedback loop including a capacitor is electrically connected between the output of the amplifier and the first terminal. A second positive frequency independent feedback loop is electrically connected between the output of the amplifier and the second input terminal. The second feedback loop preferably includes a voltage divider having a temperature variable resistor and a pair of independent heaters for varying the resistance of said resistor. The low frequency oscillator includes a pair of the novel integrator circuits and a resistive inverter circuit electrically connected together in cascade having ganged gain control following each integrator.
An integrator circuit comprising an operational amplifier having first and second input terminals and an output, said first terminal being adapted for connection with an input voltage source and including a resistor between said input source and first terminal; a first negative feedback loop connected between said output terminal and said first input terminal, said first feedback loop including a capacitor, and a second positive feedback loop connected between said output terminal and said second input terminal, said second feedback loop including a voltage divider having first and second resistors, said second resistor being a temperature variable resistor and including a pair of electrically isolated heaters for varying the resistance of said second resistor.
Claim 2
Dependent Claim
114 words
An integrator circuit comprising an operational amplifier having first and second input terminals and an output, said first terminal being adapted for connection with an input voltage source and including a resistor between said input source and first terminal; a first negative feedback loop connected between said output terminal and said first input terminal, said first feedback loop including a capacitor, and a second positive feedback loop connected between said output terminal and said second input terminal, said second feedback loop including a voltage divider having first and second resistors, said second resistor being a temperature variable resistor and including a pair of electrically isolated heaters for varying the resistance of said second resistor.
Claim 3
Dependent Claim
31 words
An integrator circuit as set forth in claim 1 wherein said second resistor is selected from the group consisting of a positive temperature coefficient thermistor and a negative temperature coefficient thermistor.