Oscilloscope app.

[Seacommander]

There have been quite a number of references on the forum about the value of using an oscilloscope for identifying the cause of problems sometimes encountered with DCC operation. Buying an oscilloscope for maybe just limited use is a big decision to make when we are all tempted by so many other things to buy for our layouts. It only just came to my attention that there are several apps available for iPads and iPhones to enable them to operate as an oscilloscope. Has anybody here tried one and if so how user friendly are they?

[96RAF]

Not seen these apps or how you get the sensing inputs to the device, but I have seen cheap Arduino based ‘scopes. How capable these are I have no idea.

Edit - It seems the vast majority of these app ‘scopes are limited to acoustic analysis as the only input (apart from one much more sophisticated app that uses additional wireless input hardware) is the device microphone.

I have a Picoscope 4-channel USB device which uses a PC as its screen, but again we are into the realms of fairly big money. Ashamedly I also have very little idea of how to use it outside the narrow field of monitoring DCC signals.

[Chrissaf]

I agree with Rob's analysis. If there is no external compatible hardware adapter interface. Connecting RAW DCC track voltage directly to any port on a mobile or tablet is likely to damage it.

[ColinB]

I must admit, I wouldn't have thought you would want a oscilloscope to debug DCC issues. I bought myself one when I retired, but I have never used it to debug dcc issues. I have found most times a multimeter is perfectly ok for most faults. Now if you want to get into designing your own circuits then yes you need one. I think the only time I used mine was when I was having issues with the lights that I had fitted on my carriage weren't lighting up properly. When I used the scope is was obvious that it was because the Hornby power supply that I thought was DC was in fact pulse width modulated. If I had realised it was a PWM power supply I needed not have bothered. The other issue with model railways is the two rails are live, with an oscilloscope you have a probe and an earth, so not always a good idea to connect it across both tracks.

[96RAF]

Staying off topic for a moment longer...

Connecting the probe and earth clip across the two rails is exactly what I do Colin as the probe is isolated from true ground at least on my device.

What I did find when using all four channels to monitor everything out of the back of an Elite is that there was a phase shift between the Track and the Boost outputs, which threw an error. This was located as a crossed trace on the Elite PCB, which in reality was transparent to the user, as the Boost output would always be connected to a Power and Signal Booster module, which also acts as a Reverse Loop module and hence flips disparate phasing to match.

[ColinB]

On a modern oscilloscope it is probably not an issue connecting the earth but if you are using a really old oscilloscope it can damage the circuit you are testing. In the old days you frequently had to remove the earth to the oscilloscope, modern ones are double insulated so not so much of an issue. I can't remember if with DCC both wires are active, definitely with CAN they are. If they are then that is another reason for not doing it. Either way for normal day to day use an oscilloscope is not that necessary.