Rip detector signal detection circuit

A detection circuit for a conveyor belt rip detector system or the like in which an AC signal is pulse modulated as an indication of the integrity condition of such conveyor belt or the like, comprising full wave rectifier means for dividing such AC signal into respective opposite polarity signal components, filter means for filtering each of such signal components to produce respective opposite polarity filtered signal components, summing means for combining such filter signal components to produce a substantially DC signal normally at a substantially constant magnitude and with DC pulses impressed thereon, said filter means comprising a separate smoothing filter means for filtering each of such signal components to produce such substantially DC signal with substantially DC pulses impressed thereon and separate high pass filter means for filtering each of such signal components to block such substantially DC signals and to pass substantially only such substantially DC pulses to said summing means, and output means responsive to such substantially DC pulses for producing a distinguishable output indicative of the integrity of such conveyor belt.

A variable level detecting circuit, comprising input circuit means for receiving a raw input AC signal containing characteristic information as pulse height modulations of such raw input AC signal, means for producing from such raw input AC signal a substantially DC signal normally at a substantially constant magnitude and carrying such characteristic information as substantially DC pulses, reference means for developing a reference signal, comparator means for comparing such substantially DC pulses and such reference signal to produce an output signal indicative of the relative magnitudes thereof, and bias means for altering such reference signal to an altered reference signal in proportion to a parameter of such raw input AC signal.