Sweep Generator Manual

The ACM Sweep Generator is a high performance laboratory instrument designed to be used with the ACM Instruments Research Potentiostat.

INDEX

1/ General Specification.

2/ Description of Front Panel Connectors and Switches.
2.1 +/- POSITIVE - NEGATIVE SWITCH
2.2 4 V / 1 V SWITCH
2.3 GRADUATED DIALS.
2.4 OUTPUT.
2.5 TEST A and TEST B.
2.6 HOLD-NORMAL SWITCH.
2.7 STOP AT B - GO BACK TO A - SWITCH.
2.8 ONE CYCLE-CONTINUE - SWITCH.
2.9 RESET-GO - SWITCH.
2.10 SET SWEEP TIME AB.
2.11 MULTIPLIER SEC.
2.12 UNITS and DECIMAL.
2.13 BACK PANEL.

3/ General Use of Potentiostat by examples.
3.1 Sweep from A to B.
3.2 Sweep from A to B to A.
3.3 Sweep from A to B to A to B etc.
3.4 To Calculate Sweep Rate.
 

1/ General Specification.

Maximum sweep range +/- 4 Volts
Maximum output current 300 mA
Potential set knob linearity on low range +/-2 mV
Sweep Times 1 second to 1 million
seconds with 100
divisions per decade
Sweep Time accuracy +/-2 %
Set potential buffered output 2 mA +/-4 V
Step Resolution over 40 mV 1 µV
Power Supply 240 VAC
Fuse 1000 mA

2/ Description of front panel connections and switches.

2.1/ +/- Positive / Negative Switch

This switch is marked + and -, in the + position the potential set by the graduated dial, will be Anodic (positive). In the - position the potential will be Cathodic (negative). If the sweep generator is connected to an ACM Research Potentiostat via the external input. The working electrode in the 3 electrode mode will be polarised in an Anodic direction with respect to a reference electrode if + is selected or a Cathodic direction if - is selected.

2.2/ 4 V / 1 V Switch.

The switch marked 4 V and 1 V sets the range of internal potential as set by the graduated dial. In the 4 V setting the range is 0-4 Volts, in the 1 V setting the range is 0-1 Volts.

2.3/ Graduated Dials.

These knobs are used in conjunction with the two switches described above. It has a ten turn graduated dial reading 1 mV per division on the low setting and 4 mV per division on the high setting. A setting lock is provided on the dial. The dial on the far left shows the start potential whilst the dial on it's right shows the stop potential or the first turning potential. See 2.9.

2.4/ OUTPUT.

These two 4mm sockets (red-high, black-low) give the sweep output and can feed any input impedance greater than 15 ohms.

2.5/ TEST A and TEST B.

These sockets allow the measurement of the graduated knobs set potential via an external voltmeter. Both outputs are fully buffered.

2.6/ HOLD-NORMAL switch.

By switching from normal to hold this allows a sweep to be paused and should normally be in the normal position. The sweep can be restarted at the pause potential by simply switching back to normal.

2.7/ STOP AT B - GO BACK TO A switch.

If stop at B is selected the sweep will proceed from potential A to potential B. At potential B the sweep will stop and remain at potential B. If go back to A is selected then the sweep will not stop at potential B but return to A potential.

2.8/ ONE CYCLE-CONTINUE switch.
If go back to A is selected then this switch becomes active. If one cycle is selected then the sweep will go from potential A to B to A and stop at A. If Continue (continuous) is selected then the sweep will continue to sweep between potentials A and B.

2.9/ RESET-GO switch.

This switch is normally held in the reset position whilst setting up potentials. In the reset position only the start potential appears at the output. Once go is selected the sweep will start to sweep in potential to point B from point A.

2.10/ SET SWEEP TIME AB knobs.

These three knobs set the sweep time for the potential to sweep from point A to B. If a sweep from A to B to A is selected then the sweep time would be double.

2.11/ MULTIPLIER SEC knob.

This knob sets the basic sweep time from 1 second to 100,000 seconds.

2.12/ UNITS and DECIMAL knobs.

These knobs multiply the basic sweep time by Units + Decimal. For example if a sweep time of 360 seconds is required then select 100 on the multiplier 3 on the units and 0.6 on the decimal. That is 100 × ( 3 + 0.6 ) = 360 seconds

2.13/ Back Panel.

This contains the IEC mains socket, the ON-OFF switch and the mains fuse. The serial number is also shown on the back panel.

3/ General Use of the sweep generator by examples.

Figure 1 gives examples of the type of sweeps available.

3.1/ Sweep from A to B.
Test A Potential = -300mV
Test B Potential = 2000mV
Sweep rate = 3.7 seconds

Select reset, stop at B and normal. Select 1V and -ve for the switches associated with the Start A dialled knob. Turn Start A dialled knob to 300. Select + and 4V on Stop-Turn B switches and turn Stop-Turn B knob to 500. This will appear as 2000mV at the Test B output as the 4 V range has been selected, that is 500 × 4. See 3.4 for sweep rate.

3.2/ Sweep from A to B to A. Set the Sweep Generator up as above but select go back to A and one cycle. Note the sweep time only gives the sweep time between A to B or B to A such that in this case the sweep time would be double.

3.3/ Sweep from A to B to A to B etc. As above but select Continue.

3.4/ To Calculate Sweep Rate. Frequently sweep rates are required rather than sweep times. To calculate this is simple. For example if a sweep rate of 3.7 mV per second is required use the following calculation.

( Potential B - Potential A ) ÷ Sweep Time = Sweep Rate
Thus
Sweep Time = ( Potential B - Potential A ) ÷ Sweep Rate

So for the example at 3.1

Sweep Rate = 3.7 mV per second.
Potential B = 2000 mV
Potential A = -300 mV

Thus Sweep Time = ( 2000 -(-300)) / 3.7

        = 2300 ÷ 3.7
        = 621.6 seconds or 620 seconds.

Thus in this instance 620 seconds should be selected as the sweep time by selecting 100 and multiplying by 6.2.