Low frequency oscilloscopes?

[walters]

When i monitor a Low frequency oscillator or use a function generator that is set
from

1.) 0.05 Hz to 30 Hz
2.) 0.1 Hz to 25 Hz
3.) 0.2-12Hz
4.) 0.25-8Hz

A.) Why does a Analog oscilloscope use a Flashing strobing dot and not use a steady sinewaveform that you can visually or graphically see, so you can measure the period/time of the waveform?

B.) Why doesn't a Analog oscilloscope let low frequency be measure more clearly in real time?

C.) What would u have to modify in a Analog oscilloscope to make low frequencys at theses ranges more visual in real time?

D.) What kind of oscilloscope measure low frequencys better , that can do it in real time? (so its not flashing or strobing a dot)?

 

[kevpat]

An analog oscilliscope is actually very good at showing low frequency data as it is showing it in real time as it changes. The voltage from the circuit controls a beam that passes across the face of the scope the inside of the screen is coated in phosphor and when the electron beam comes in contact with the screen it glows, hence the small moving dot seen at low frequency. It is still a dot at high frequency it is just that it is refreshing so quickly ythat the phosphor glow does not get the chance to fade.
It has been a long time since I have used an analog scope so I might be missing a trick here but if you turn the intensity up as high as possible the trace will take a little longer to fade away and you may be able to make out the whole signal very faintly on the screen.
A digital scope samples the signal so it would display the whole signal but even at low frequencies it is not as accurate as an analog scope just more convenient.

 

[echo47]

If you turn off the lights in the room, you may see the entire waveform glowing faintly.

In the analog scope days, we used storage scopes to view slow or single-sweep waveforms. A storage scope has a cleverly designed CRT with adjustable persistence. Simply crank up the persistence knob, and the waveform remains glowing on the screen for as long as you wish. That was very helpful for the slow sweep rates in sampling scopes, TDRs, and spectrum analyzers. I still use a many-GHz sampling TDR in an old Tektronix storage scope mainframe.

Today, digital scopes store the waveform in memory, and display it in various convenient ways.

 

[walters]

What u mean by a single-sweep waveforms? what is that?

What is TDRs mean?

But why can't a regular Analog oscilloscope display low frequencys?

It doesn't display low frequencys so you can see the "whole" waveform at once in real time, why is that?

What is this "Persistence" parameter do in the oscilloscope?
(CRT with adjustable persistence)

What tricks is there to know when using a cheap analog oscilloscope when measuring low frequencys time/period measurements?