Signal conditioner 123

The model 123 is a new microprocessor controlled 3-channel signal conditioner for Piezoelectric (PE) or Integrated Electronic Piezoelectric (IEPE) sensors. The model 123 incorporates a charge amplifier when used with PE sensors. An integral 0, 4 or 10 mA, user selectable, current source with 20 Vdc compliance voltage is utilized with IEPE sensors. A user friendly interface allows programming Input Sensitivity and Output Sensitivity, then allowing the instrument to calculate the amplifier gain. All gain selections are stored in non-volatile memory and reinitialized when power is applied. Gain can also be entered directly if desired. The model 123 utilizes a microprocessor SLEEP mode to eliminate high frequency clock noise and their associated harmonics. The microprocessor WAKES momentarily to acknowledge front panel switch depressions, then goes to SLEEP immediately after processing and executing the requested function. This allows the amplifiers to operate with minimum self generated noise and provides clean, clock free amplified signals. The model 123 also uses low noise linear voltage regulators instead of switching regulators to minimize interference. The model 123 uses 12 bit DACs, for each channel, to set amplifier gains from 0.00 to 999.9 with 0.5% precision. Amplifier gains can be changed “on the fly” without damage to the instrument. The model 123 provides 1.5 Hz to 230 kHz broadband frequency response, with optional plug-in, 4-pole Butterworth high pass and low pass filter modules available. Filter selection is provided via rear panel switches. Front panel annunciate LEDs display filter selections. Each channel can drive 10 mA into a 1k ohm load.