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Sensor Carrier Demodulators
High Gain Research & General Purpose Basic

The CD12 is a portable, high-gain Carrier Demodulator, used to provide transducer excitation, and to amplify and demodulate the output of variable-reluctance transducers, strain gages, linear and rotary variable differential transformers, and potentiometric transducers. It operates with full or half-bridge transducers, delivering a 10 Vdc output for inputs ranging from 0.9 to 75 mV/V.

Ideal for use in R & D labs, medical laboratories, and field use. The compact instrument accurately displays the transducer signal on its integral 5-inch analog meter, as well as providing two analog outputs, one of which is controlled by the suppression circuitry. A suppression circuit is incorporated into the CD12 to critically observe signal deviations around a reference level. Input signals can be suppressed from 0 to 10 Vdc in either a positive or negative direction using a single multi-turn dial.

This circuit enables the meter to be used as a null indicator for reading accuracies of 0.1%.


2-arm, 4arms bridges-switch selectable

Meter readout plus dual analog outputs

Scale expansion of X3 and X10

Selectable frequency response

Zero suppression to ±100% FS

The CD15 Sine Wave Carrier Demodulator operates with variable reluctance transducers to provide a DC output signal for dynamics as well as steady state measurements. A 5kHz sine wave excitation is applied to the two inductance ratio arms of the transducer and the resulting output is demodulated and amplified using the latest integrated circuit techniques. The DC output is obtained from an active filter circuit and gives a uniform response from steady state to 1000 Hz. The low impedance sine wave excitation allows operation with the transducer located over 1,000 feet from the CD15.

The unit is small enough to be included in the case of most receiving and recording instruments.

Features Output:

±10 Vdc

Compact: may be used on bench top or mounted in existing enclosures

Regulated against line voltage variation

Solid state reliability


  • Ranges of ±1, ±5, ±20, ±75, ±250, ±1000, ±3000 psid
  • ½% Accuracy
  • Accepts corrosive liquids and gases, both sides
  • High natural frequency
  • Low sensitivity to line pressure