REVIEW: Vevor SDS1104 4 channel scope

[HenrikOlsson]

If you don't know, read up on what Auto/Normal/Single mode actually does. Also, there's no indication of trigger level on the scope screen, where do you have that set?

[Demon]

I have it set at 4.9V along the right edge of the screen. That's exactly the thing that I haven't totally figured out yet. Sometimes it's there, sometimes it's not.

When nothing displays, I adjust it down, fiddle through the modes, and eventually it shows up. Could be the scope, could be me.


From what I've observed:

- AUTO is constantly scanning, RUN/STOP button locks display when needed,
- NORMAL locks display until next trigger,
- SINGLE locks display, RUN/STOP button resets.

The annoying thing with SINGLE, is that the scope reverts to AUTO after I reset RUN/STOP. Then I have to cycle through the modes to put it back in SINGLE (takes a few button clicks each time).


I like to learn as mush as I can on my own, then read up when I have specific questions (like now I'm going to read up on auto, normal, single modes, as well as when does voltage trigger level appear on the screen).

[Ioannis]

Wish you to enjoy your new toy!

Regarding the modes and trigger it is necessary to read the manual. Every scope may have its own quirks.

Nice buy, at a nice price.

The fast rotation of the encoder may produce that spike like pulses because of capacitance on the lines an high pull up resistors.

Ioannis

[HenrikOlsson]

If you expect the signal to swing between 0 and +5V then set the trigger level to somewhere around 2.5V.
As with input coupling the trigger coupling can usually be set to either AC or DC. Perhaps you have it set to AC and that's why the trigger level marker does not show on the right hand side of the screen.

SINGLE waits for the trigger condition to be met, does an acquisition, displays it on the screen and stops. You have to re-arm the trigger.
NORMAL waits for the trigger condition to be met, does an acquisition, displays on the screen, re-arms the trigger and goes back to waiting.
AUTO is like NORMAL but if the trigger condition is not met within a certain time it does the acquisition anyway, re-arms the trigger and starts again.

You should have some sort of indicator, either as a LED or a screen annunciator telling you if the scope is "trigged" (as with a repetitive waveform like PWM output) or "waiting" (as with something like a monitoring a button press).

I have no experiece with your particular scope and have not looked at the manual but I would highly recommend reading it as even these $200-$400 scopes comes with an enormous amount of functionality. It's just incredible what you can get for less than brand name multimeter costs these days.

[Demon]

would your mains power be at 60Hz ?
hint 16.667mS...

Yes it is (Canada, ~110VAC)

... the A B debounce looks very uneven between rising and falling edges. the unequal phase shifts so introduced will make R.E data interpretation interesting, especially at varying rotational speeds

Yeah, I noticed the uneven edge times when I was doing my mechanical testing.

Off the top of my head, I was planning on waiting for a first signal and watch for 2nd signal, then reset loop if no more signals. I haven't done any coding on it yet, but I was planning on keeping it very straight-forward.