Oscilloscopes can be very frustrating for students with little experience with them. This work sheet is designed for the novice user. It gives a step by step set of instructions on how to setup your oscilloscope and then use it. These procedures also outline most of the problems that students experience and gives solutions. The goal of this work sheet is to make the experience of reaming to use an oscilloscope as easy as possible.
1. Turn on CADET II (the BCD 7 segment display will show "00" when CADET is on).
2. Turn on oscilloscope.
3. Plug in a probe on channel 1 and another on Channel 2.
4. Adjust the intensity of the signal on the screen, if necessary (use intensity dial).
5. Adjust the focus of the signal on the screen, if necessary (use focus dial).
6. Turn the Sec/Div dial to .5 uSec.
7. (Tektronics oscilloscopes) Turn the Vertical Mode switch to Ch 1 (which is channel 1). Notice that the switch has three settings (Channel 1, Both and Channel 2).
The setting you select determines which probe's signal is being displayed. You will be using this switch frequently. If during your experiment you're not getting the signal you expect, it is usually because you have forgotten to change your channel.
(Beckman oscilloscopes) Make sure that the Ch1/Ch2 button is on Ch1. The button below it says Mono/Dual. This button is for showing one or both channel's signals on the screen.
8. Turn the Volts/Div dial to:
(Tektronix oscilloscopes) Use the 10x highlighted area on the dial as your scale (this is because you are using a 10x probe) Turn to 5 Volts/Div.
(Beckman oscilloscopes) Turn the dial to .5 Volts/Div. Remember, that one division will be equal to 5 Volts and not .5 Volts!!! This is because of the 10x probes you will be using.
9. Turn the AC/GND/DC Selector switch to GND. and use the position dial to place the signal line at zero Volts.
10. Connect the Ground clip of the oscilloscope probe to the Ground of the CADET.
11. Switch the AC/GND/DC Selector switch to DC.
12. Touch the probe to Ground on the CADET. The oscilloscope read 0 Volts (the same signal as in step 9). If you get an AC signal on the oscilloscope it means that you forgot to use the Ground clip of the probe (it happens to all of us at one time or another; just clip the probe's ground clip onto the Ground of the CADET).
13. Touch probe to +5V on CADET. The oscilloscope should read 5 Volts (a flat line at the first major division above the x axis). All of the +5V connectors on the CADETs have been tested and are at the correct voltage; so if your oscilloscope isn't at the first major division above the x axis you need to adjust your Volt/div dial).
14. Turn the Vertical Mode switch to Ch 2 and repeat steps 8 through 13 for Channel 2.
15. All of the oscilloscopes have been checked and do work properly (and are calibrated).
Now that the oscilloscope checks out you will only need to use the following dials/switches on the oscilloscope for your labs:
1 ) AC/GND/DC Selector switch for each channel.
AC used when checking AC signals (such as square wave on CADET)
GND shows you where 0 Volts is set for the channel. Allows you to properly position the 0 Volt signal on the Y axis.
DC used when checking DC signals (such as the output from an inverter
when applying a DC input (.25 V increments)).
2) Channel 1 (or 2) Volts/Div
The scale will have to be changed to accurately measure the spikes on
the power line. Whenever you change scales you should recheck where 0 Volts
is on the oscilloscope screen (by simply switching AC/GND/DC Selector to
GND to check).
3) Sec/Div Dial
This will have to be adjusted based upon the frequency you are using
on the CADET. If the signal line disappears after changing this setting
then simply adjust the intensity up until it appears again.
4) Vertical Mode Switch (or button)
Make sure you are viewing the right channel!! If nothing happens when you probe something it is probably because you are displaying the other channel.
Be sure not to touch any of the dials or switches not mentioned in this paper (For example: the switches for external triggering or coupling). Accidentally switching to the external triggering mode (or test mode) may lead the student to think that the oscilloscope is broken when in fact it is simply waiting for an external signal before activating.