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Advanced Measurement Technology 273A User Manual

Potentiostat/galvanostat
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  • Page 1 0RGHO$ 3RWHQWLRVWDW*DOYDQRVWDW 8VHU·V 0DQXDO 8VHU·V 0DQXDO (  3ULQWHG LQ 86$...
  • Page 2 Copyright © 2002, Advanced Measurement Technology, Inc. All rights reserved. *Princeton Applied Research is a registered trademark of Advanced Measurement Technology, Inc. All other trademarks used herein are the property of their respective owners.

  • Page 3: Table Of Contents

    3.1.14. Rear-Panel Connectors ........... . . 13 3.1.15. 273A/92 Electrochemical Impedance Interface Option ......14 3.1.16.
  • Page 4 3.2.10. 273A/92 Electrochemical Impedance Interface Option ......19 4. INITIAL CHECKS ..............21 4.1.
  • Page 5 6DIHW\,QVWUXFWLRQVDQG6\PEROV This manual contains up to three levels of safety instructions that must be observed in order to avoid personal injury and/or damage to equipment or other property. These are: DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction is not observed.
  • Page 6 Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 7: Introduction

    Model 273A. Be sure you understand the information in Section 1.4 about the polarity convention used in this instrument. The 100 V output and high current capability of the Model 273A make it potentially lethal if not used with care and respect. Chapter 2 describes recommended safety precautions for operating it.

  • Page 8: Controlling The Model 273A

    Appendix C. After you inspect the Model 273A for shipping damage, but before you begin to use it, run the initial performance checks given in Chapter 4 to ensure that the instrument operates correctly. Then, using the operating instructions given in Chapter 5, you may begin operation of your unit.

  • Page 9: Polarity Convention

    The Model 273A Potentiostat/Galvanostat has been designed for optimum reliability, and requires no periodic maintenance. This manual contains no service information. The Model 273A is very difficult to service in the field; special fixtures and services are required that are not readily obtainable except at the factory or at certain affiliate facilities.
  • Page 10 Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 11: Safety Considerations

    As defined in EEC Publication 348, Safety Requirements for Electronic Measuring Apparatus, the Model 273A is Class I apparatus, that is, apparatus that depends on connection to a protective conductor to earth ground for equipment and operator safety. Before any other connection is made to the apparatus, the protective earth terminal must be connected to a protective conductor.
  • Page 12 A table printed on the rear panel of the Model 273A adjacent to the power-input assembly indicates the actual line voltage range for each number.

  • Page 13: Cell Cable

    To avoid the possibility of dangerous electrical shock, always have the cell disabled when working with the cell connections. The cell status is determined by the two keys in the cell area of the Model 273A front panel. These keys function as follows.

  • Page 14: Defects And Abnormal Stresses

    Note: This switch provides no protection in either position. The cable connections can be handled safely only when the front panel cell disable switch is set to OFF. Note that the Model 273A is controlled even when the cell isn't ON, that is, having the cell OFF does not cause an overload condition.

  • Page 15: Transient Sensitivity

    Copper, aluminum, or brass are the recommended materials). Because the Model 273A has an internal low pass filter connected to the power line, the ac line cord is unlikely to be a source of radio frequency interference. If the internal filter seems to be inadequate, try decoupling the power line with an external filter.
  • Page 16 Transients that enter the instrument via the line cord can generally be suppressed by external line-transient filters. Suitable devices are commercially available. Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 17: Characteristics

    3. CHARACTERISTICS 3.1. Specifications The following specifications apply at the nominal line voltage ± 10% and at a temperature of 25°C (77°F) unless otherwise stated. 3.1.1. Power Amplifier 1. Compliance Voltage: > ± 100 V 2. Maximum Output Current: > ± 1.0 A 3.

  • Page 18: Ir Compensation

    In other words, shutting the Model 273A off does not cause the default values to be restored. They can, however, be restored by reinitializing the system via FUNCTION 10. The use of FUNCTION 10 is described in Section 5.2.4.

  • Page 19: Rear-Panel Connectors

    OUTPUT signal), X output (identical to front-panel E MONITOR signal), contact closure lines for pen up/down control, and ground. 7. RS-232C INTERFACE: Serial port for control of the Model 273A from an external computer. Associated switch assembly sets RS-232C parameters (exception: Terminator, <CR> or <CRLF>, is set by switch in the GPIB switch assembly).

  • Page 20: 273A/92 Electrochemical Impedance Interface Option

    5 volts rms. This signal can be used to modulate the signal sent by the Model 273A to the cell, and can be attenuated as desired. It is controlled by commands from an external computer via the GPIB or RS-232C port.

  • Page 21: Internal Organization

    Although the Model 273A is a complex instrument, its basic organization is straightforward as depicted in Fig. 3. The following paragraphs discuss the Model 273A, as represented in the figure, in some detail. The symbols used in Fig. 3 are, for the most part, conventional, and require no description.

  • Page 22: Cell Switch And Relay

    (relay and solid-state switch) provide a feedback path for the Control Amplifier when the cell isn't connected. The gain in this path is nominally X1 (solid state switch) or X1.5 (relay). If one volt is applied, the Control Amplifier output will be 1 V or 1.5 V, as appropriate. Model 273A Potentiostat/Galvanostat User’s Manual...
  • Page 23 Fig. 3. Model 273A Simplified Block Diagram. Chapter 3—Characteristics...

  • Page 24: Ir Compensation

    The GIGAIN command further affects the effective time constants. See the ITC command in the Model 273A Remote Programming Command Handbook for more information. Longer-time scale coulometry experiments (TMB...

  • Page 25: 273A/92 Electrochemical Impedance Interface Option

    The externally generated ac signal is input at the AC INPUT connector and is combined with the signal generated by the Model 273A before it is applied to the cell (see Fig. 4). The /92 option board has three output connectors (AC I OUTPUT, AC E OUTPUT, and MULTIPLEXED OUTPUT.
  • Page 26 Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 27: Initial Checks

    Any damage noted should be reported to the carrier and to Princeton Applied Research. Be sure to save the shipping container for inspection by the carrier. If you have not used a Model 273A or 273 before, this procedure also will help acquaint you with the operation of the instrument.

  • Page 28: Procedure

    Plug the Model 273A into a suitable source of ac power. (See Chapter 2 for line voltage selection and safety information.) 9. Set the 273A's POWER ON/OFF switch to ON. 10. Reinitialize the system by pressing the following sequence of keys: [FUNCTION] [1] (0] [YES] [ENTER] 4.4.
  • Page 29 Press the ENTER key as many times as are required to blank the bottom line of the display. The Model 273A is now ready to run the experiment. The programmed sequence will be initiated in the following step. Press START. The following should be observed. Note: START can be pressed at any time to restart the check sequence.
  • Page 30 18. Press the CELL ON/OFF key, establishing the Cell OFF state. The associated indicator light should extinguish. 19. Set the Model 273A POWER ON/OFF switch to OFF. This completes the initial checks. If the indicated behavior was observed, the user can be reasonably confident that all circuits up to and including the electrometer are functioning normally.

  • Page 31: Operating Instructions

    A battery-powered parameter backup system retains all selections and parameter values. When the 273A is powered up, all selections and parameter values are as they were at the end of the previous operating session. The default values can, however, be restored by reinitializing the system via FUNCTION 10.
  • Page 32 Messages, which can be cleared by pressing any key, and Remote Error Messages, which only occur when controlling the Model 273A from a remote computer. Remote Error Messages are in two parts, the Error #, and then the Command that caused the failure. Remote Error Messages can only be cleared by taking appropriate action at the remote computer or cycling the power.

  • Page 33: I Overload And E Overload

    5.2.2. I Overload and E Overload These two indicators are located between the Scan Status and Alphanumeric Displays. The I OVERLOAD indicator lights if the cell current exceeds two times the selected Current Range. Because it is impossible to reach currents of 2 A, this lamp cannot light when the current range is "1 A."...

  • Page 34: Scan Setup Group

    Note: Under remote control via the rear panel GPIB or RS-232C port, steps as small as 25 µV (MR = 1), or 2.5 µV (MR = 0), can be attained as explained in the Model 273A Remote- Programming Command Handbook).
  • Page 35 The +/- key reverses the polarity of the expression and can be pressed at any point before [ENTER] is keyed. b. To set and enter a Vertex Current of 1 mA when operating on the 100 mA range, key: [E/I 2] [.] [0] [1] [ENTER] Since the desired current (1 mA) is 1% of the selected Current Range (100 mA), E/I 1 is set to ".01".
  • Page 36 When it is accessed, the message REINIT SYSTEM? is displayed. At that point the operator presses the YES key or the NO key (1 or 0 or the keypad), as appropriate, followed by ENTER. If YES, all parameter selections are cleared Model 273A Potentiostat/Galvanostat User’s Manual...
  • Page 37 FUNCTION 11, PRINT OUT INSTALLED OPTION: This function allows the user to determine at a glance whether an option is installed in the unit. When accessed, the number corresponding to the installed option is displayed. If a unit is equipped with the 273A/92 option, the number "92" would be displayed.
  • Page 38 If the Model 273A is being controlled from an external computer via the RS-232C or GPIB inter- face, the rate at which data can be taken will be faster with this override in the NO state.
  • Page 39 Another operation cannot be initiated for 4 ms. The step feature allows the Model 273A to perform double-potential step chronoamperometry, in which the applied potential starts at E/I 1, remains there long enough to let the sample come to equilibrium with the solution, steps to E/I 2 for DELAY 2 seconds, and then steps to E/I 3, which continues to be applied.
  • Page 40 Status of the Scan. Possibilities include: Delay Time Remaining (Delay specified in seconds). Time Remaining Until Drift Measurement Can be Made (Delay specified in mV/s). Alternatively, measured drift rate if measurement has taken place. iii. Stopped Scan. Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 41: Interface Group

    A brief description of each follows. 1. TALK: This indicator lights when the Model 273A has output ready to send to the host computer. It goes out when the Model 273A has finished sending this output. The TALK indicator does NOT signal that the host computer has transmitted a TALK message.

  • Page 42: Control Group

    1. SCANNING: This indicator is off at power-up and on during each active scan. At powerup, the E/I APPLIED indicator is lighted, indicating that the 273A is ready to apply the previously speed E/I APPLIED level. (It won't actually be applied, however, unless both the CELL switch and the CELL ENABLE switch are ON.) If a scan is initiated by pressing START, the...
  • Page 43 SCAN1 from E/I 1 to E/I 2. iii. Scan STOPS on reaching E/I 2. During DELAY 1 the cell can be either ON or OFF, as programmed. During SCAN 1 the Cell will be ON. At the end of the scan, the E/I 2 indicator will remain lighted. The cell will remain ON or OFF according to the state of the applicable Override.

  • Page 44: Mode Group

    (consistent with the ±100 V compliance of the Control Amplifier) to establish the desired working electrode potential. b. GALVANOSTAT: In this mode the 273A controls the cell current at the specified faction of the selected Current Range (up to the maximum of two times the Current Range; one times the range if 1 A is selected).

  • Page 45: Input Group

    EXTERNAL INPUT is +0.5 V, at a time when a programmed potential of +0.5 V is applied, the net potential seen by the Model 273A will be + 1.0 V, and the working electrode would be controlled at + 1.0 V with respect to the reference electrode. A positive applied potential will make the current tend to be more anodic.

  • Page 46: Filter Group

    The EXTERNAL INPUT is controlled by the EXT ON key. When pressed, the associated indicator lights and the Model 273A becomes responsive to potentials applied to the EXT INPUT connector. If pressed again, the indicator goes out, indicating that potentials applied to this input will be ignored.
  • Page 47 Feedback is that the correction is continuous. As a result, correction remains effective even at the fastest scans possible with the Model 273A. While the technique is the only one possible for rapid scans (scans of 100 mV/s or faster), there are several significant disadvantages.
  • Page 48 Press "POSITIVE FEEDBACK." The associated indicator will light and positive feedback compensation will be established. Note: This pushbutton is a toggle; to turn the compensation off, simply press POSITIVE FEEDBACK again. 2. R NOT KNOWN: Model 273A Potentiostat/Galvanostat User’s Manual...
  • Page 49 Press the POSITIVE FEEDBACK key, establishing Positive Feedback mode operation. c. Program the Model 273A to apply a 62.5 Hz, ±50 mV square wave to the cell. The following parameter values can be used. Note: The ±50 mV figure is not critical.
  • Page 50 FUNCTION 13 sets the interval between current interrupts. The range is .004 s to 30 s, with a default setting of 1 s. (In doing Curve Acquisition with the 273A controlled from a host computer, the interrupt timing is controlled by the computer.) FUNCTION 17 sets the percentage of correction, adjustable from 0% to 200%.
  • Page 51 Note: The default values give good results in many applications. Do not change these values using the applicable functions unless you are well grounded in current-interrupt IR compensation theory. This is particularly true of functions 17, 18, and 19. A prerequisite to evaluating these parameter selections is that an oscilloscope be connected to the rear-panel electrometer monitor connector to observe the current-interrupt waveform, as discussed in the following paragraphs.

  • Page 52: E Monitor

    There are three keys, nine indicators, and one BNC connector in this group. Their function is to set and monitor the Model 273A's full-scale current range. One of the eight available current ranges is always selected, and the corresponding indicator lit. A cell current equal to the selected current range gives 1 V at the I MONITOR connector.

  • Page 53: Output Group

    The key moves it downwards. In the AUTO mode, the Model 273A automatically seeks the current range that causes the I MONITOR Output to be between 15% and 190% of full scale, that is, between 150 mV and 1.9 V.

  • Page 54: Rear Panel

    (Fig. 8). A brief description of each follows. Pinouts for the multi-pin connectors are provided in Appendix A. Warning! For operator and equipment safety, the power should be off when connecting or disconnecting cables. Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 55: Cell Interface

    X- and Y-axis drive signals are to be reversed (corrosion), cable C178 is recommended. One end of this cable has a connector that mates with the Model 273A's RECORDER INTERFACE connector. At the other end are two pairs of banana plugs and two leads terminated in spade lugs that provide the pen-drop contact closure.

  • Page 56: Auxiliary Interface

    Model 273A. A relay contact closure inside the Model 273A is brought out to the pen drop leads. These leads float with respect to ground. Many recorders have a pen-drop circuit configured such that the pen drops when the closure occurs.

  • Page 57: Multiplexed Output

    Input voltage must be no greater than 5 volts rms. This signal can be used to modulate the signal sent by the Model 273A to the cell, and can be attenuated as desired. It is controlled by commands from an external computer via the GPIB or RS-232C port (refer to the Model 273A Remote-Programming Command Handbook).
  • Page 58 EXT position. In the DUMMY position, a 100 k , 1% resistor inside the Electrometer Housing is substituted for the cell. The feature is useful for determining that the Model 273A is functioning correctly. Note that this is a locking-type toggle switch. To change the setting, it is necessary to grasp the "bat"...

  • Page 59: Model 273A Standard Environmental Conditions

    5.5. Model 273A Standard Environmental Conditions 5.5.1. Operating Conditions This equipment shall meet all specified performance criteria when subjected to any natural combination of stress.

  • Page 60: Non-Operating Conditions

    This equipment is designed to meet or exceed the requirements of the following standards: A. BS EN55022 (1987), Class B B. BS EN50082 (1992): 1. IEC 801-2:1991 2. IEC 801-3:1994 3. IEC 801-4:1988 BS EN61010-1 (1995), Installation Category II, Pollution Degree 2. Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 61: Appendix A. Pinouts

    APPENDIX A. PINOUTS A.1. Cell Interface (36 pins) FUNCTION 1, 19 Counter Electrode 2,20 Counter Electrode Shield Electrometer Output* 6, 8, 24, & 26 I / E Guard (Driven) 7, 25 I / E Input +24 V (100 mA maximum) -24 V (100 mA maximum) Dummy Cell Sense Electrometer Shield (gnd)

  • Page 62: Auxiliary Interface (Mating Connector Db9S)

    EXT. TRIG line. If the command WFT 1 is applied, operation will resume when a logic 1 is applied tot he EXT. TRIG line. In applications where the Model 273A is being used with a Model 303A via a Model 307 Interface, DISPENSE this signal causes the Model 303A to do a Dislodge/Dispense operation on command from an external computer.

  • Page 63: Ieee-488 Gpib Interface

    STIR This signal controls the Model 303A’s Stir function in response to commands from an external computer. The underlying assumption is that the Model 303A is being used with a Model 305 Stirrer. A.4. IEEE-488 GPIB Interface PIN # FUNCTION DI01 DI02 DI03...

  • Page 64: Rs 232C Interface

    -12 V Note that the 273A RS-232C port is configured as a female DTE port (Data Terminal Equipment) rather than as a DCE (Data Communications Equipment). Thus, cabling to most microcomputers can be accomplished with a standard reversed or switched RS-232C cable, also known as a null modem cable.

  • Page 65: Appendix B. Rack Mounting

    APPENDIX B. RACK MOUNTING The Model 273A can be mounted in a standard 19 inch relay rack by means of the Princeton Applied Research 1715-0206 Rack Mounting Kit. This kit consists of two special side panels with integral mounting flanges and four screws. To install the kit, proceed as follows.
  • Page 66 Model 273A Potentiostat/Galvanostat User’s Manual...

  • Page 67: Index

    Coulombs Indicator ..... . 32 273A/92 option ......14 Current Interrupt IR Compensation .
  • Page 68 OUTPUT and AUX DIGITAL Connector ..18 FUNCTION 21, CALIBRATE 273A ..32 OUTPUT Group ......47 GALVANOSTATIC MODE .
  • Page 69 Safety Considerations ..... 5 STABILITY versus SPEED ....38 Safety Requirements .
  • Page 70 Model 273A Potentiostat/Galvanostat User’s Manual...

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