As to the scopes.... A digital scope usually has storage facility. That means one can freeze a wave form on the screen and look at it. That is especially handy when one looks at a single event which triggers the display..... which an ordinary analog scope does not have. Once the pulse flashes through, it is forever gone. Further - a digital scope usually has a numeric display on the screen which tells you the amplitude in either RMS or peak to peak of a voltage/waveform, frequency, period of a wave form, movable cursors which show how many milli seconds,or microseconds are in-between the two cursors etc. There are horizontal and vertical cursors. A digital scope replaces a couple of pieces of equipment like volt meters etc.
As that other contributor already mentioned, each type of scope has advantages over the other. A digital scope - especially a cheaper one with a lower bit A/D converter does not show the true waveform especially at higher frequencies... shows more like a stepped waveform (like a staircase) neglecting to show maybe important little spikes riding on the wave form. An analog scope shows that - provided the vertical bandwidth is high enough. I have a 50GHz digital Tektronix scope which shows everything on the screen in numeric read-out that can possibly be known about any waveform - including FFT function (Fast Fourier Transfer function) or spectrum analysis to look at the harmonic content of a waveform.
The difference between DC and AC coupling is simply that DC coupling shows an AC wave form being offset by a DC voltage.
AC coupling blocks a DC voltage and the display is always let's say in the middle of the screen - no matter how much the DC level shifts.
Re Analog and Digital multimeters..... Almost all analog multimeters show the RMS (Root Mean Square) value and are very slow to show faster variations of voltages compared to digital ones. Analog meters also suffer from a very low input resistance which makes measuring high impedance circuits or sources impossible because the they would load down the source(s) and the reading would be way off compared to the digital meters which have a very high input impedance - typically above 10Meg Ohms to 100MegOhms and higher and do not load the circuit to be measured. The digital meters also sometimes have the annoying habit of flickering numbers due to a slow settling time. The great advantage of digital meters is the numbers of digits being displayed precisely telling one the voltage down to the micro volt. The better industrial ones display usually 5 1/2 and 6 1/2 digits with automatic polarity sign. They can also be controlled by a remote computer like through an HPIB interface and their measurements be displayed on a computer screen..
I hope this helps
So - each one of these different pieces has its pros and cons - depending on the application.
Edit: violet - you are of course correct. I mean I could have gone into a very long assertion here in regards to all this but I figured it would be sufficient what I wrote. Thank you for your input!
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