Any Oscilliscope Experts out There?

[apostolakisl]

I know very little about oscilliscopes except that they show you the wave form along with noise. I also know they are expensive and I am not going to spend $1000 for one. I am also pretty sure that most oscilliscopes have a gazillion functions that I don't need. I just want to see power line noise in real time so I can clean up my house from seamingly random issues.

 

I find this http://www.ebay.com/itm/NEW-DSO-Nano-V2 ... 2a14062f4b on ebay. I will pay $100 for an oscilliscope if it will show me power line noise in real time. Is this going to do that for me?

[Brian H]

May not be a good choice.

 

Has a limited analog bandwidth of 200kHz and Insteon is 131.65KHz, but par for the cost.

 

Is only DC coupled and may make some signals hard to display.

 

Full scale with a X10 probe is ~100 volts per division. The wiki indicated it could in theory display 800 volts but never tried.

I didn't see a X10 probe and the X1 has a maximum of 80 volts.

 

Notice the RED warning. On the sales page.

The input common and the USB port common are tied together. Certain connections could result in sparks or a shock.

This is the fact that bothers me. Though other scopes could under some circumstances be the same.

 

The users manual is also avilable from the sales page.

http://www.seeedstudio.com/depot/dso-na ... ?cPath=174

 

More data:

http://seeedstudio.com/wiki/index.php?title=DSO_Nano_v2

 

You may want some feedback from others, who may have different opinions. As the cost is reasonable for its features.

[ELA]

I would echo Brian's excellent comments.

In particular you state that you want to view noise. That requires some sort of isolation to be safe. As Brian Pointed out the commons are tied together!!!

 

If you found or built a 1:1 isolator that covered the noise in questions range then you might still get away with it.

 

One other thought is that "noise" is a very relative term. If you viewed an active Insteon network with a few dimmers turned on you will see tons of noise.

Is that a concern or not? I recently was viewing a lot of Insteon waveforms while running communications reliability testing. With a few dimmers on the noise really stood out, yet the communications was 100%.

 

You said you wanted to clean up some communications issues. I would look for signal suckers first before looking for noise. If you are sure you have eliminated all signal suckers then I would focus on possible noise. Mostly because noise is so much more difficult to identify. Like I said you may see noise, but is it an issue?

If the issue is noise, it is more likely to cause problems in an already marginal nework comm. environment. If filtering signal suckers can improve the signal to noise ratio the noise may no longer matter.

 

I good communications reliability test I feel is the best available at this point. Test each suspect device and when the reliability tests low, unplug any devices that might be suspect and retest. Once identified as a problem who cares whether it was noise or signal sucking ( an engineer of course ). A filterlinc cures both in most cases.

 

It is a laborious process. Good luck.

[apostolakisl]

Curiously, I just updated to 3.1.7 today. Suddenly all is working better. ???? I don't know. I just wish there was a way to actually see what is going on. It is such a guessing game. I wasn't having any communication issues on insteon to insteon communication, it seemed to all relate to isy communication, so maybe it just needed a reboot? Or maybe the new firmware did somthing?

 

For example, this morning a device query would take a couple seconds to complete for most devices. After the firmware udpate it happens almost instantly. I probably had 15 failure to communicate errors on my screen every morning for the last 4 days. Usually I have 1 or none.

 

I just feel like I'm blind when things don't go as expected. I would so love to just be able to see the wave forms. But I'm not spending thousands on an oscilliscope. Furthermore, I can only imagine that it will take me hours to figure out how to use it.

[Brian H]

Although tuned to 120KHz for X10.

The X10Pro XPCP phase coupler. Has a separate isolated L and N for each phase. I have used one to see stuff on a power line with a scope. One Input on the power line. The other Input as an Output to the scope.

[apostolakisl]

Brian,

 

I hope that you find my ignorance tolerable. How does that help you out? Is it becuase it selectively passes through the insteon frequency range to the oscilliscope? Would that not hide the noise? And what kind of inexpensive oscilliscope would be sufficient?

 

What I feel like I need is to be able to flip a switch/plug something in/turn something on, and see immediately what affect it has on noise. Maybe that isn't really helpful, but it seems like it would be.

 

Anyway, after updating the firmware I am now getting zero failures to communicate and my programs are all executing in full. Perhaps it is the firmware changes or perhaps it is just the reboot.

[Brian H]

The scope and XPCP was more of an experiment to observe X10, Insteon signals and noise {in the X10 and Insteon frequency range} on the power lines.

I used a scope that could be triggered by the AC line so I could see where in the cycle the noise and signals where.

For practical testing. May not be the best way to go.

 

I personally use some X10 senders and a JV Engineering XTBM Signal Tester.

It can read the signal levels to 9.99 volts signal, noise to .99 volts, the signals frequency. If is was an X10, the message sent and if it was correct.

It does indicate an I with an Insteon signal but can't decode the messages.

 

I can turn things on and off and observe signal level changes and noise increasing or decreasing.

Though most things that effect X10 also do for Insteon. The tests are not 100% for Insteon. For now no one has a stand alone Insteon tester.

Though I understand HouseLinc 2 has some tests in it and the ISY Scene Tests sometimes can show problems.