Appendix C: I/O Connectors
70
The E Monitor signal is filtered using an RLC circuit. It has a bandwidth of approximately 1.1 MHz when
connected to a high-impedance input.
External Signal In
External Signal In allows you to add a voltage to the Interface 5000’s Signal Generator. It is a two-wire
differential signal with the negative side connected to the Interface 5000 floating ground. This signal is summed
with the other signal-generator sources, including the Bias DAC, the Scan DAC, and the DDS output.
The signal generator output is directly connected to the potentiostat’s input. When the cell is turned on in
potentiostat mode, the feedback is such that a negative signal-generator output creates a positive differential
electrometer signal, which corresponds to a negative working electrode versus reference electrode voltage.
The polarity of the External Signal In signal is inverted at the signal generator’s output. As described above, a
negative input signal on this input will create a positive change in the working electrode versus reference
electrode voltage. The input impedance of this signal is 2 kΩ.
Temperature Monitor Signal
The Interface 5000 offers temperature testing in the range of –50 to 600°C. A 1000 Ω (at 0°C) platinum RTD
(resistance temperature detector) according to European standard (DIN/IEC 60751 or simply IEC751) is used for
the temperature measurement. The RTD sensor contains a resistor that changes resistance as its temperature
changes. The RTD is excited with a precision 1 mA current source. The A/D normally reads 1.000 V when the
RTD is at 0°C, and its resistance change is 3.85 Ω/°C for the temperature range 0 to 100°C. Platinum RTD
elements are available in two types of constructions: thin-film and wire-wound. Platinum RTDs offer several
advantages:
• A wide temperature range (–50 to 500°C for thin-film, and –200 to 850°C for wire-wound)
• Good accuracy (better than thermocouples)
• Good interchangeability
• Not affected by corrosion or oxidation, and
• Long-term stability.
The RTD resistance is read using a two-terminal connection. The RTD is wired between Pins 3 and 4 of the
Monitor Connector. A current source applies 1 mA between these pins. A ∑∆ A/D converter continuously reads
the voltage-difference between the pins.
Gamry will not calibrate an RTD you use. If you require higher accuracy for the temperature
reading, you must perform an RTD calibration. Any manufacturer of the RTDs can perform such service. As
an alternative, you may buy a more accurate RTD sensor, such as Class A, AA or 1/10DIN (temperature
range permitted).
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