Model 179 Computer-Controlled Charge Amplifier / Integrator
Description
The Model 179 computer-controlled charge amplifier module features variable gain and output scaling and accepts either differential or single-ended inputs. Adjustable parameters include: accelerometer sensitivity, differential or single-ended mode, scaling, filter setting, external calibration and zero mode.
Input Channel A = chargev
| Accel sensitivity: | Any value from 2.0 to 200pC/g |
| Output scaling: | 1mV/g, 10mV/g, 20mV/g, 100mV/g |
| Gain accuracy: | ±1% |
| Input mode: | Differential or single-ended (-IN tied to common) |
| Maximum input: | 50,000pC peak per input (50,000pC differential): 2,800pC peak with sensitivity set to 2.0 – 9.9pC/g 12,500pC peak with sensitivity set to 10 – 49.9pC/g 50,000pC peak with sensitivity set to 50 – 200pC/g |
| Frequency response: | 20kHz at 50,000pC peak input level, increasing to >35kHz at 25,000pC peak input level (or lower) |
| Calibration: | Internal 1015pf ±1% capacitors convert ExtCal voltage signal to charge, which can be applied to amplifier front end |
| Zero mode: | Relays replace charge converter output with short to common |
Input channel B = millivolt, with optional 4mA excitation for transducer
| Calibration: | External ExtCal voltage signal can be applied to front end |
| Excitation: | 4mA constant current can be tied to +S, with -S tied to common |
| Gain: | 1 or 100 |
Features common to both output channels
| Filter: | Eight-pole Butterworth lowpass at 12Hz, plus OUT, six-pole Butterworth highpass at 5kHz, 15kHz or 25kHz |
| Filter input signal: | Select either charge input or millivolt input |
| Pre-integration Filter: | Three-pole Butterworth lowpass at 250Hz, 500Hz, or 1kHz |
| Integration Select: | Accel, velocity, displacement, or unfiltered (5Hz-12kHz) accel |
| RMS/DC Select: | Either AC signal or DC representation or RMS value |
| Limit Detect: | Two front-panel LEDs indicate saturation at charge amp, before filters, and at integration stages |
| Offset: | Less than 5mVDC at output |
| Noise: | Less than 3mV RMS, filter in, input disconnected |
| Mechanical: | 5.5” x 13.5” board, used with Model 5020-102 rack |