Vevor SDS1104 4 channel scope

Paid $256.99CAD+FreeShipping direct from Vevor.ca. Seems to be a clone of the Owon SDS1104 (best price I can see is $318+shipping+taxes on Banggood).

https://i.imgur.com/ihdiRjL.jpeg


Played with it with a rotary encoder. It didn't take me long to be able to do single scan and auto.

- The USB cable cannot connect to PC, it has a USB type B connector (waiting for USB-A cable from amazon)
- PC software seems to be only for display, there doesn't seem to be any feature to tweak the graphs.

I really do like having 4 channels; all 4 probes are included. I will be able to scan an encoder, and check a pulse from PIC to see how fast I can check encoder pulses.


Turning the encoder at normal speeds looks like this:

https://i.imgur.com/3l08afK.jpeg


It doesn't have protocol decoders (I2C, SPI, USART, etc), but I wasn't looking for that on a bargain scope. And I really needed the scope now to help figure debounce circuits.

(couldn't post all links in first post due to limit)


Turning it really fast and increasing scan speed has some attempts looking like these:

500uS

https://i.imgur.com/fG3NUlZ.jpeg


200uS

https://i.imgur.com/nX9byVg.jpeg

The weird thing, it that the voltage can go above 5V and below 0V when I turn the encoder real fast.

I'm using USB voltage from the PC, so no idea how that happens. Maybe the scope loses it's place and drifts beyond the actual limits; I'm not knowledgeable enough to determine, and reviews are few.


EDIT: Argh, I'm probing an RC circuit. Voltage rises as capacitor charges, lowers as it discharges...

There's something hinky going on. Sometimes it won't scan the probes. I still haven't figured out what exactly.

But I go though the MODES, eventually the RUN/STOP buttons goes red, I reset it back to green, and all is well.

It could just as easily be me doing something wrong.


I'm getting quickly used to using the colour codes on the probes; real handy feature when using multiple probes.

Side note, I really like the scope. Playing with 2 probes on EC11 rotary encoder and 3rd probe on RV17 potentiometer with switch.

Attachment 9675

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?

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).
:)

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

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.

Quote:

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Originally Posted by richard

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

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Yes it is (Canada, ~110VAC)

Quote:

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Originally Posted by richard

... 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

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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.