An Introduction to Using the Agilent 54622D Digital Oscilloscope, E3631A DC Power Supply, 34401A Digital Multimeter, and 33220A Arbitrary Waveform Generator By: Walter Banzhaf University of Hartford Ward College of Technology USA Equipment Required • Agilent 54622D Mixed-Signal Oscilloscope with two 10X attenuating probes and digital probe kit • Agilent E3631A DC Power Supply • Agilent 34401A Digital Multimeter with two test leads (one red, one black) • Agilent 33220A Function/Arbitrary Waveform Generator
Page 1 2 Procedure Equipment Required, Introduction Table of Contents 3 4 5 7 8 9 10 11 12 13 14 Part One – The Agilent 54622D Mixed-Signal Oscilloscope- Analog Inputs Basic Start-Up Procedure Quick Performance Check Probe Compensation Features to Try - Vectors Features to Try - Averaging Features to Try - Using Cursors to Measure Time & Voltage Features to Try - Using "Quick Meas" to Measure Time & Voltage Features to Try - Saving Waveforms to a Floppy Disk Importing Saved Waveform Displays Into a Word
Part One – The Agilent 54622D Mixed-Signal Oscilloscope- Analog Inputs The oscilloscope is the most versatile measurement tool you have available in the laboratory. What follows will help you to learn about making initial adjustments to your oscilloscope (and its probes), to get it ready for viewing signals. You will also learn to use some of the very useful features of this instrument.
Basic Start-Up Procedure: (Refer to the picture of the oscilloscope front panel as you go through this procedure). 1) Turn the oscilloscope ON by pressing the white button at the lower right corner of the CRT screen (the graticule of the cathode-ray tube). You should see the “Startup Menu”, which includes Softkeys (buttons directly under the CRT screen) labeled Getting Started, Using Quick Help, About Oscilloscope, and Language. Try them all.
3) QUICK PERFORMANCE CHECK: Connect a 10X attenuating probe to Channel 1. Change three (3) settings as follows: a) Vertical Section: Channel 1, change Probe Factor (a softkey that says Probe) to 10:1. You can do this by pressing the oval button labeled “1”, and then turning the control called the “Entry Knob”, located just to the right of the CRT, below the horizontal section, with an illuminated curved arrow above it. b) Vertical Section: Channel 1, change to 500 mV/div scale.
5) Three controls need to be adjusted to give a satisfactory display: the Vertical Section volts/div and position, and the Horizontal Section time/div. These controls can be adjusted two ways: by YOU, or by the oscilloscope. For now, let’s have the oscilloscope do the adjustment. Press the Autoscale hardkey, a white button just above the Vertical Section.
6) PROBE COMPENSATION: This step is a “MUST DO” procedure, each and every time you turn on an oscilloscope. In fact, you must do it if you move a probe from one channel to another, and especially from one ‘scope to another ‘scope (for example, from the analog to the digital ‘scope). If you don’t make sure that each probe is compensated properly, you can wind up with incorrect waveforms and major measurement errors.
Features to Try - Vectors: The 54622D oscilloscope is a digital instrument that makes a graph of voltage versus time by putting individual dots on the screen. By contrast, an analog ‘scope creates a graph which is continuous (no dots are used). Each dot represents an (x,y) pair (time, voltage) in a Cartesian coordinate system. If the dots are close together, your eyes are fooled and you see a continuous line; if the dots are too far apart, you’ll see individual dots.
Features to Try - Averaging: Our building, and most laboratories, are “dirty” in the electromagnetic sense. This is due to the power line noise, computer systems, lighting, and RF (radio-frequency) signals that create unwanted voltages on top of the voltages we do want to measure. One way to minimize the problem (clean up the “dirt”) is to use the Averaging feature of a digital ‘scope. Look closely at the waveform below, on the left.
5) Leave averaging ON and set the # of Avgs to 4,096. Connect the probe tip to the Probe Comp output. Note that the change in the display (from flat line to squarewave) is very slow indeed. QUESTION TO PONDER: If time base is set to 200 µs/div, and there are 10 divisions on the graticule, how long does it take before 4,096 complete “sweeps” have occurred? This is the time needed for the display, with squarewave removed, to become a flat line, if one sweep begins right after the prior one ends.
4) Now press the (X Y) softkey, which will make the Y checked, and both the Y1 and Y2 cursors (dashed horizontal lines) are at 0.00V (this is the bottom of the waveform). 5) Press the Y2 softkey, and move the Y2 cursor line to the top of the waveform by using the Entry Knob. Now Y2 is about 4.94 V, and the ∆Y = 4.94V. Your display should look like the one on the right.
What is wrong with the amplitude value of 5.19 Vpp is that it is a bit wrong (too big), due to the noise on the Probe Comp signal. You can see that the dashed horizontal cursor lines are positioned above and below where they should be (on the top and bottom of the waveform). Get rid of the noise by pressing Acquire hardkey, and then the Averaging softkey (and average 8 waveforms). We can see that with averaging on, the amplitude is now 4.979 Vpp, 4 % lower than 5.19Vpp.
4) You can see that the file was saved successfully by pressing the Utility hardkey, then the Floppy softkey, and then the File: softkey. A list of the file(s) saved will appear on the display, with the date and time they were written. This is a good opportunity to see if your ‘scope’s clock is set correctly; if it isn’t, press the Utility hardkey, then the Options softkey and the Clock softkey and make changes to the year, month, day, hour and minute as needed.
HANDY HINTS: Pressing and holding ANY key (hardkey or softkey) will bring up a help screen on the display. This is a great way to learn about oscilloscope features. Softkeys are at the bottom of the display. They will appear when a Hardkey is pressed. DON’T use the oscilloscope to delete files on your floppy disk, except files that IT created. Autoscale may not give a desirable result; use Undo Autoscale if this happens.
Part Two – The Agilent 54622D Mixed-Signal Oscilloscope- Digital Inputs Features to Try - Turning On the Digital Channels 1) OK, now that we are familiar with the mixed-signal oscilloscope using its analog inputs, now let's get acquainted with the digital inputs and their controls. 2) First, return the oscilloscope to its “Default” condition by pressing the Save/Recall Hardkey in the File area of the front panel, then pressing the Default Setup softkey.
Notice that the D0 line, at the bottom, is a squarewave, going between logic level 0 and 1,and D1 - D7 are straight lines (logic level 0). 7) Let's turn off the unneeded digital channels: turn the Entry Knob until the arrow is next to D1, and press the left-most softkey. This will toggle D1 on and off. Leave it off. Now, repeat this process, turning OFF D2 - D7. The display below shows D0 and D7 ON, and D7 is about to be turned OFF.
Note that using the Digital Channel Position control (directly under the D7 Thru D0 hardkey) we can move the D0 display up and down on the screen, as needed. Also look at the top of the graticule in the display above; the D7 _ _ _ _ _ _ _ ¤ D0 box shows that D7 D1 are turned OFF, and that D0 is going between logic 1 and 0. 9) If you have a 4-bit counter available (e.g. a TTl 7493 IC or CMOS CD40161 or CD4024use 4 of the 7 bits), connect the input to a suitable oscillator.
13) Another triggering method that can be used is Pattern triggering. Press the Pattern hardkey in the Trigger Section, and use the Entry Knob to select D0. Press the L softkey (L = logic Low), and the rotate the Entry Knob to select D1. Press the L softkey again, and select D2; again press the L softkey. Lastly, Select D3, and press the up arrow ( ↑ ) softkey, to choose positive-edge triggering on channel D3. This process will now make the trigger occur when D2 - D0 are Low, and D3 has a positive edge.
Part Three – The Agilent E3631A Power Supply A power supply is used to provide DC voltage(s) needed by a circuit that doesn't supply its own power. The Agilent E3631A is actually three power supplies:0 to 6 V, 0 to 25 V, and 0 to -25 V. In this section you will see how to set the voltage of each supply and how to use "current limiting" on each supply to protect your circuit.
Setting the voltage limit is quite simple to do, and to understand. Refer to the front panel picture on the previous page, and the instructions below. Setting the Output Voltage: Let's say you have built a circuit that needs +5 V. So, you follow the process above to set the +6 V supply to +5.000 V. Do this now, and verify that the output voltage is 5.000 V. Or, your circuit needs +/- 15 V, in which case you follow the process above to set the +25 V supply to +15.00 V, and the -25 V supply to -15.00 V.
Setting the Current Limit: 1) Let's assume you have set the +6 V supply to 5.000V, and the display indicates you have the +6 V supply selected. To set the current limit, press the Display Limit button, then the Voltage/Current button. Use the control knob and the "Resolution Selection Keys" (the < and > keys underneath the control knob) to adjust the current limit to 0.020 A. 2) This setting of 0.020 A means that no matter what you do, the current from the +6 V supply (which is now set to 5.
Part Four – The Agilent 34401A Digital Multimeter The DMM (digital multimeter) is a very important laboratory instrument. This section will show you how to make three of the basic measurements: voltage, resistance and current. The 34401A has many capabilities beyond measuring V, R and I; consult the Agilent User's Guide for information on measuring frequency, period, continuity & diodes, and using the many features and functions of this DMM.
Measuring DC and AC Voltage Key points: You must insert the voltmeter leads across the two points in a circuit for which you want to measure the voltage. Use the red and black input jacks as shown below. You can use the rear panel red and black input jacks also (be sure to select front or rear). If you use front and rear, you can easily and quickly select one of two voltages. The DMM will Autorange, unless you override it by selecting a range.
Measuring Resistance Key points: NEVER measure resistance in a "live" circuit. Turn off all power to the circuit. If an ohmmeter is used in a "live" circuit, at best you will get incorrect readings; at worst you can seriously damage the DMM. You must insert the ohmmeter leads across the two points in a circuit for which you want to measure the resistance. Use the red and black input jacks as shown below. Use the red and black input jacks (on the right) as shown below.
Measuring Current Key points: You must insert the ammeter leads in series to measure current in a circuit. Use the red and black input jacks (on the right) as shown below. You can use the rear panel red and black input jacks also (be sure to select front or rear). If you use front and rear, you can easily and quickly select one of two currents. The DMM will Autorange, unless you override it by selecting a range. You can choose the number of digits displayed, using the DIGITS buttons.
Part Five – The Agilent 33220A 20 MHz Function/Arbitrary Waveform Generator (AWG) Introduction The Function Generator is the instrument that creates input signals used to test circuits and systems in the laboratory. This section will show you how to create some basic waveforms commonly used in the lab: sine, square, triangle and pulse waveforms, including DC offset.
The Front Panel Controls Refer to the diagram below as you perform the procedures that follow.
Step One - Creating a Sinewave With No DC Offset Voltage, High Z Load Resistance 1. A basic waveform you will now produce is a 1 kHz, 100 mVpp sine wave with no DC offset. Connect the Output (a BNC connector on the front panel) to the vertical input of an oscilloscope. 2. Turn the power on by pressing the white button at the lower left of the front panel. You are reminded that you can get Help for any key by holding it down. 3. The display says 1.000,000,0 kHz, with a picture of a sinewave on the right.
3) In the display to the right we can see that our 200 mVpp sinewave now has a minimum value near 0 V (-400 uV = -0.4 mV), and a maximum value of 200.3 mVpp. Note the ground symbol on the display. 4) Remove the 100 mV DC offset using the Knob. Our sinewave is still 200 mVpp. 5) Method 2: Press the Offset softkey, to select LoLevel. Raise this to 0.00 V. Now, press the "HiLevel" softkey, and use the Knob to raise the high level to 200 mV.
4) You can turn the squarewave into a pulse train by pressing the Duty Cycle softkey. Change the duty cycle to 20% (the range is 20% to 80%), either using the Knob or the Numerical Keypad. Your 5 Vpp, 1 kHz pulse train, goes between 0 V and +5 V. Verify that yours looks like the one to the right. 5) If you need a pulse with a duty cycle less than 20% or more than 80%, use the Pulse hardkey Step Four - Creating a Triangle or Ramp Waveform, High Z Load Resistance 1) Press the Ramp hardkey.
Other Useful Information and Review As covered in the procedure, but of such importance that its repeated again: The output must be terminated by 50 Ω for voltages set on the AWG to be accurate. OR, for loads that are much higher resistance than 50 Ω, you can use the Utility key, then Output Setup softkey, and Load softkey to select High Z. The Help function tells us that "Load Impedance / High Z / 50Ω Sets the value of the load attached to the [Output] connector (used for voltage settings).
