If I try to display in real time slow events or low-level signals at low frequencies, my analog two-channel 20-MHz oscilloscope is an essential instrument. On the digital scope I have, the same task is very difficult, hard to set up, and annoying to wait for triggering.
On my 200-MHz DS4024, if I want to see what is actually happening and if I set the time/div at 1-Sec/div, I must wait for the scope to accept a trigger to get a sweep to start and then the display will be delayed up to 14-secs before the scope will show anything on the screen. I might even have to wait up to another 14-seconds before I can get the digital scope to trigger again. This is very frustrating.
As a beginner, I would most often like to see cause versus effect. If I spoke into a microphone and adjusted any component of a simple 1-transistor amplifier, and attempted to probe the signal into the transistor on one channel and also probed the output on the second channel, I would immediately see everything happen immediately as it happened and this really helped me to understand how circuits work.
I could also set the intensity of a free-running display to have a really thin, sharp line. This means I could explore every point on a circuit in this free running mode(i.e. 10mSec/div) and visually measure them at a glance.
Because I can see all the voltage levels instantly. I am able to measure them quite accurately using the scope graticule alone and I don't have to use my DVM. What's more, the 10x probes of the scope would not upset the circuit I am working on like the long unshielded probes of the DVM would. The fat trace on a digital scope often overwrites the simulated graticule, and since the trace is thick, the digital scope greatly diminishes the at-a-glance accuracy when I want a quick visual examination of all test points of the project I am working on.
And if I wanted to see tiny signals at 1-mV per division and trigger on them I could easily see them clearly on my analog scope. This is impossible on my digital scope, triggering is very poor or non-existent when attempting to view low-level signals that have an amplitude of only one or two minor divisions. Auto-triggering on my digital scope is often just a joke.
When I trigger a signal on my analog scope, it displays the signal until the end of the viewing area and keeps the displayed waveform
only for the spit-second persistance of the display.
The digital scope has infinite persistance with normal triggering, and even after I remove the probe, the signal is displayed.
This can cause me to think a signal is present when it is not.
When is comes to viewing with power supply D.C. levels, low voltage signals, and low-frequency audio, the analog scope is undeniably the best.
When I first started to learn electronics, I able to learn quickly because I could use my analog scope for all my simple experiments and clearly see signals with just a slight tweak of a triggering level knob and unlike my digital scope, not require me to turn several switches and push a half-dozen buttons to see what was going on in my experimental circuits.
Many years later, when I began to work with MCU's a digital scope was essential, for example, to single-sweep and hold a complex 4-channel display of simultaneous digital signals, or even to just viewing an RS-232 bit stream, but the need for this digital instrument was long after I first started to play with and learn the workings of electronics.
I still use both scopes and really appreciate the convenience of use and clean display of my analog scope and the necessity of having a digital scope for troubleshooting and developing the really complex robotic projects I am playing with now.
My digital DS4024 now sits on top of my Hong-Chang 20-MHz and it fits perfectly, like a saddle on a horse. This is very important, because it raises the DS4024 to a much higher viewing level and makes it so much easier to see the display without hurting my neck!