Dual Channel Differential Electrometer

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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 noise

The 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 port

The 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.

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%.

FD223A Instruction Manual

E. Ermolayeva, H. Hohmeyer, E. Johannes, D. Sanders "Calcium-dependent membrane depolarisation activated by phytochrome in the moss Physcomitrella patens" Planta 199. 1996: 352-358

To place an order for this product, please contact the appropriate WPI office or distributor.

Customers from North America can order direct from our corporate office:
World Precision Instruments
175 Sarasota Center Boulevard
Sarasota, FL 34240-9258

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International customers, please see our office and distributor contact information list.

M3301L	Micromanipulator
M-3	80° Tiltling base
RC1T	Reference cell (Ag/AgCl)
2547	Driven guard shield for FD223AP Probe
MEH1SF	Microelectrode holder
FD223AP	Replacement probe (includes calibration)

No application notes are available for this product at this time.