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Details
The FD223a is a dual differential, high impedance amplifier/electrometer designed specifically for electrochemical measurements using ion specific (K+, Na+, C1-, etc.) or pH electrodes. The instrument is very stable, drift free, and features a built in provision for measuring and adjusting input leakage current. DC levels may be independently adjusted for each probe channel.
Overcoming noiseThe ability to locate the sensing probes directly at the measurement site overcomes the noise introduced by the long cables usually needed to bring the measured potential to the instrument. Signal-driven guards at the probe input maintains the specified high resistance and reduces the stray capacitance of the probes. Careful design, coupled with quality component selection, particularly in the headstage, results in an excellent amplifier with low noise and wide bandwidth. The FD223a will faithfully reproduce the measured signal. To reduce the noise and stray capacity even farther the probe housing includes a signal driven guard. A portion of this inner driven shell is exposed at the probe tip allowing a spring shield to be extended over the electrode holder and microelectrode.
Probe test portThe
amplifier features a probe test port that permits testing of the electrode
test feature and setting of the probe leakage current, (IG). A standby
mode is included and should be used when attaching glass microelectrodes
or electrode holders to the probe input. While in the standby mode the
voltage at the probe input is clamped near zero volts thus protecting the
input.
Specifications
| Input Impedance | > 10^15 ohm, shunted by 0.5pF |
| Input Capacitance | 1pF, nominal |
| Leakage Current | 75fA max |
| Gain | 1.000± 0.1% |
| Output Resistance | 50 ohm |
| Input Swing Voltage | ±10V |
| Rise Time (10 to 90%) | 5us, small signal |
| Noise (0.1 Hz to 10 kHz) | <100uV p-p, input shorted |
| Baseline Stability | ±0.1mV/day |
| Position Controls Range | ±600mV |
| Physical Dimensions | Case:8.8 x 21.0 x 17.5 cm (H x W x D) Probe:12.7 x 65 mm (D x L), 1.8 m cable |
| Power | 90-265VAC, 50/60Hz, 10VA |
| Probe Handle | 6.5 x 65 mm (D x L) |
| Shipping Weight | 2.5 kg |
| Operating Conditions | Equipment is intended to be operated in a controlled laboratory environment. Temperature: 0-40°C; altitude:sea level to 2000m; relative humidity: 0-95%. |
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