SENSING ENGINEERING INNOVATION CA/04/N, NL, NH, EH Charge amplifier: 04 system Low noise, extended low frequency response; input range, output up to 3.16V/pC, overload LED; bandwidth 0.1/100 kHz CHARGE AMPLIFIER NOISE The dominant source is input voltage noise, amplified by the non-inverting gain of the transducer interface section (Fig.I.). This latter is a function of the signal source impedance, 1/w (Ct + Cc), and charge amplifier transfer impedance 1/w Cf being unity (best case) for open circuit input. Note also that in the O/C input case, increased transfer impedance improves signal/noise by prorate enhancement of the inverting/no inverting gain ratio. It is safe to say that noise evaluation and comparison should be subject to representative input loading-open circuit data may mislead. Minimal noise design centres on the choice of early stage active devices and their configuration; ergonomic facets contributing to operational versatility may override absolute minimisation. CA/04/N Low noise charge amplifier, with a 0.1/1 Hz (-3dB) switchable minimum frequency option, provision for adding custom single pole low pass roll-off, LED overload indicator. NORMALISING A three decade digi-switch and x1/x10 multiplier provides output normalising over a 1/110pC/g transducer sensitivity range, with 1% worst case resolution. Min. (1.00), max. (10.99) digi-switch settings confine range to minimum 1% resolution, caters for 10 & 100pC/g transducer nominal sensitivity tolerance spread. OUTPUTS Setting digi-switch and multiplier directly to the transducer charge sensitivity calibrates O/P1 to 10mV/g, O/P2 to 1V for range switches setting 0.316, 1.0, 3.16, 10, 31.6, or 100g. Normalising scale factor greater than unity produces a pro-rata gain reduction, hence O/P1 & 2 scaling, and increase in peak g. Finchley Avenue, Email [email protected] Mildenhall, Suffolk IP28 7BG Web www.djbinstruments.com A UK company with UK-based manufacturing, assembly and calibration in-house.

SENSING ENGINEERING INNOVATION CA/04/N, NL, NH, EH Charge amplifier: 04 system Low noise, extended low frequency response; input range, output up to 3.16V/pC, overload LED; bandwidth 0.1/100 kHz By way of example, with the amplifier normalised to 50pC/g a 10pC/g transducer rescales O/P1 to 2mV/g peak O/P1 level will increase from 1200 to 6000g (Vs = ±15V). OVERLOAD Absolute value peak detector indicates signal level exceeding 8V. CALIBRATION The CAL terminal connects to the amplifier input (virtual earth) via a 1nF capacitor. A voltage applied to CAL converts to an input charge (1mV = 1pC). APPLICATION...