Scopes display information on a Voltage vs Time plot. There are two kinds
- Phosphor screen
The digital ones have a few more features (like calculating RMS and average values, holding min/max values, automatic triggering, and movable cursors) but they both work fine. There is a phosphor screen one in the bay which was donated to us years ago.
Steps to using a phosphor screen scopeEdit
- Turn on
- Set to DC coupling if you want the DC and AC components; AC if you only want the AC (best for small signal AC on top of DC)
- Connect a signal at the frequency (ish) you want to work in. This can be either on one of the channels, or on the ext trigger input.
- Select trigger channel that you connected your signal to
- Move the trigger level up and down with the "trigger level" knob until the waveform is stationary.
- Change your voltage or time scale accordingly to get the best data.
- For DC measurements: set the channel you're on to GND momentarily. That is the vertical (DC voltage) zero point (if its off the screen youll need to be on a different setting)
- Read the seconds/div and Volts/div from the knobs.
- Count divs horizontally between points of interest (it's periodic, there's no "correct" reference location)
- Count divs vertically from your zero point if you're on DC coupling, or between points of interest for AC coupling
- Remember all the settings you used for next time!
- Turn off, unplug, clean up.
You'll notice that at some trigger levels the wave looks nice (if you attached a nice AC wave of some periodic sort), and as you turn it up and down it degrades into scary waves going every which way. The trigger sets the voltage level at which the scope looks for a consistent rising (or falling, you can set this, theres a switch on the front) edge/curve in the wave. It will then fix the point at which there is a rising curve at that voltage level in place on the screen - which makes the waveform stationary and readable.