OWON HDS 200 Handheld Oscilloscope w/ builtin DMM/AWG

[mojoe]

I don't know if you've seen this video, but W2AEW did this on a breadboard:

I'll have to say, that yours is the nicest looking one using this simple design. I'm going to box up my cobbled together version, but it will be in a plain looking project box

Of course, the idea of a curve tracer (octopus) is quite old. There are several ways to make one. Years ago, I made a traditional one, using a 6 V transformer.

I've been playing about a bit with scope settings and resistor values. First, I found that you need to use DC coupling, as AC coupling will cause the trace to move downward when you attach a component, like a diode.

I decided to only use 3 V from the SG, as this is enough for even LEDs, but not enough to blow up 3.3 V ICs. With this change, I had to go with a 47 Ohm resistor between the SG and Ch 1. I set Ch1 (X) to 500 mV/div to get more resolution on the voltage knee for diodes. I set Ch2 (Y) to 50 mV/div to keep the trace on the screen, with the voltage and resistor I am using. The 200 us that you used still works fine.

My mistake. I forgot that the sinewave is 5 Vpp,  not RMS. At 5 V, it wouldn't work with a blue or white LED.

Thanks for posting about your version. It integrates very nicely with the Owon scope.

[bungle]

I don't know if you've seen this video, but W2AEW did this on a breadboard:

I'll have to say, that yours is the nicest looking one using this simple design. I'm going to box up my cobbled together version, but it will be in a plain looking project box

Of course, the idea of a curve tracer (octopus) is quite old. There are several ways to make one. Years ago, I made a traditional one, using a 6 V transformer.

I've been playing about a bit with scope settings and resistor values. First, I found that you need to use DC coupling, as AC coupling will cause the trace to move downward when you attach a component, like a diode.

I decided to only use 3 V from the SG, as this is enough for even LEDs, but not enough to blow up 3.3 V ICs. With this change, I had to go with a 47 Ohm resistor between the SG and Ch 1. I set Ch1 (X) to 500 mV/div to get more resolution on the voltage knee for diodes. I set Ch2 (Y) to 50 mV/div to keep the trace on the screen, with the voltage and resistor I am using. The 200 us that you used still works fine.

My mistake. I forgot that the sinewave is 5 Vpp,  not RMS. At 5 V, it wouldn't work with a blue or white LED.

Thanks for posting about your version. It integrates very nicely with the Owon scope.

I hadn’t seen that particular video before, I looked at a couple of other similar ideas though.

I own an octopus tracer and a couple of real scopes, so my use case for this wasn’t to replace those. Nor was it to even attempt to replicate the increased functionality that us possible when you have PSU/transformer to play with.

Rather i was looking at what was possible using just the built in functions, specifically not needing extra cables or a psu. Being a portable scope, it  seemed most useful to be able to use the tracer adapter without then needing power or carrying a lot of extra pieces.

This way it can be used not just mobile but also when operating isolated from mains ground is important.

Also as it seems like a lot of beginners might have the HDS as their first and only scope, and likely not also own an external sig-gen, so it should work for them also.

As it turns out though, you can separate it from the owon, connecting X and Y with bnc cables, and use an external sig-gen to provide a 12V or greater sine and you can then view zeners above 5V etc also.
I am thinking of adding a dedicated bnc for that on the banana side with a switch to selectand a higher value series current limiting resistor.

btw,if you want to use the enclosure I found that almost exactly matches the owon dimensions, you can get it from Amazon or at least get the specs from the listing…

https://a.co/d/9SRdW1Z

and bnc couplers from Amazon come in sets of 5 cheap, they are made of crappy pot metal but saves me keeping 3 of my real ones in the a kit that’ll only get used occasionally

https://a.co/d/5z3ZSV2

[mojoe]

Yes, the dimensions of that box are just about perfect. I measured my scope earlier, and came up with pretty much the same dimensions. I think I'll 3D print a box, as at audio frequencies, a metal box is not needed.

[bobxyz]

Has anyone figured out exactly what the HORizontal Refresh High/Low mode does?  The manual simply says:
  Set the refresh rate to "High" or "Low".

It seems to also be a persistence on/off control.  Any idea how many frames of persistence is enabled in High mode?  Is it timebase dependent?

[csuhi17]

Has anyone figured out exactly what the HORizontal Refresh High/Low mode does?  The manual simply says:
  Set the refresh rate to "High" or "Low".

It seems to also be a persistence on/off control.  Any idea how many frames of persistence is enabled in High mode?  Is it timebase dependent?

It seems to me that it increases the update of the waveform on the display.
if you send a swept signal to it, you can see that the amount of rising edges increases, but so does the thickness of the line.

It's not similar to persistence at least, I tested it on my Micsig with the lowest setting of 100ms and the two signals looked different.

[bobxyz]

Here's an example of what I see when looking at CANbus with Refresh set to High and then Low:


The Refresh=High seems to have a fraction of a second of persistence.  When stopped, if I shift the waveform left/right, the extra overlaid waves disappear and only a single trace remains (just like the Refresh=Low example)

[Evgeny]

This is the refresh rate of the screen.

[mixail]

Hello everyone, our oscilloscopes have pretty decent software. Need help with code
https://github.com/seritools/owowon

[Anthocyanina]

Thanks, yeah, no new firmware available from farnell's site. i got this from a contest, so it seems no warranty, which sucks, I'll look around and see if the owon firmware is fully compatible. The board and everything inside just carries the owon part numbers, so the hardware should be the same, but who knows if if will recognize the owon firmware without any fiddling.

Thank you

That's a good question, because multicomp reduce the memory in the 242 and 272 series to 6k for some reason?
The Owon firmware is a bit tricky, there are multiple hardware and software editions.
My 272s is V3 and if I see correctly they are already at V6.

If you simply have an Owon, you can see its data in the menu item System/System/F4/About.
You can use the Version number to get the latest firmware from the owon site.
If multucomp specified its own numbering, it can be difficult.
It might help to identify if you share the version number and production date from the board.

element14 replaced my defective unit. the new unit shows V6 for firmware and it is also a newer hardware revision. one thing i'm not happy with with the replacement unit is that channel 2's vertical accuracy is significantly off in the higher voltage range, not unusably off, but enough that it bothers me. a 16vpp signal reads 15.6 on channel 2, and reads 15.92 on channel 1. that's about 2.5% from what it should be, so still within spec, but still annoying to see, especially when the other channel reads much closer to the actual value.