DSO Nano V3 scope - Newby requires help to use!

Hi folks - sorry for barging in here - total newby to electronics and need some assist. I work mostly on autos and with vast amount of sensors need to upgrade my skill set. After much searching decided on DSO Nano V3 to start with - 1st job is the check a crank sensor on 12v auto system - had a goot route around the web for infor as the instruction manual is pathetically worse than useless. So with my limited knowlege set about trying to get a reading from the sensot at the ecu - got the factory diagram so not a problem location the wires (2 of them for crank & cam sensors - both Hall effect type). Cannot get probes down into plugs so use Power Probe wire piercing probes and attached to them. from what I gathered I needed to set the scope for either 0.1v or 5v and anywhere from 5mv to 50mv. Result - nothing - or at least nothing visable to me. Can anyone assist in helping me understand and set this up to show me a decent freq & duty square wave form??? I will only ever be working in 12v systems if that helps????

Sounds like you don't even know how to set up the scope properly.

The user's manual which you should have linked is only 15 pages. Get familiar with it. According to that manual, the maximum input signal frequency is 1 MHz. You had better hope your signals are slower than that.

A good start would be to get a decent used bench oscilloscope. You can probably find one good to 20MHz, dual trace, for what you paid for the Nano.

That little toy is not good for 1MHz- it has 1Msps sampling rate. That makes it good for about 100kHz real world signals maximum, really more like 50kHz. I would not consider this more than a toy, and barely good enough for audio.

It sounds more like you might not be familiar with how to use an o'scope. A used analog 'scope is a good way to get some experience, and it will work a lot better than that piece of... er, toy.

http://www.seeedstudio.com/document/pdf/DSO%20Nano%20V3%20User%20Manual%202.pdf

Maybe that DSO is doing subsampling as explained at http://www.bitscope.com/adc/?p=3 hence the discrepancy between 1 Msps sampling rate and 1 MHz input frequency both listed in the manual.

Those little scopes are very handy to always have in your bag, useful for a lot of things, but yes, not the capabilities of a good bench scope at all. High speed logic it won't do, but many other things it can. Poor sight is vastly more useful than no sight...

The hall sensors may be open-collector, so you may see nothing without a pull-up resistor on the output.

I found exactly one place in the manual where it says "MHz" and that was regarding an in-built signal generator.

In fact, it says:

Virtual Broadband 0-200kHz

But of course, a scope with 200kHz bandwidth is not good for looking at 200kHz signals. A square wave at 200kHz on such a scope will look pretty much like a sine wave. You need something more like 9 times the bandwidth to get a good representation of a square wave.

geez…

I was given one of these as a gift (years back)… and since I never knew how to use a real scope, I never knew what to do with this DSO Nano ‘scope’…

sure is a lot negative comments about it.

You really need to have some experience to understand how the limitations distort what you are seeing.

I have the 72Msps model that has dual analog inputs and two more digital only inputs. Just going through the menus to find settings to change them is a royal pain, and my cell phone has a much larger screen. The bandwidth changes depending on the V/div settings. And because the designer inserted a typo into their original documentation, everyone out there claims it has a 72MHz bandwidth.

Yet you can calculate the expected bandwidth from the schematic, and it agrees very well with the tested bandwidth of around 4MHz.

At least the model I have, uses two ADCs so it does sample at 72Msps with two channels. Use all 4, it goes to half that. With the earlier model, it splits 72Msps between channels.

polymorph:
I found exactly one place in the manual where it says “MHz” and that was regarding an in-built signal generator.

I don’t know which manual you are looking at. I am look at the one the OP linked.

It quite clearly states on page 3, section III Major Functions Inbuilt Test Signal 10Hz~1MHz(1-2-5 stepping)

Scope snobbery, got to love it :(

Toolman666 is doing auto work. The signals he will be interested in are low voltage pulses, between a few 100Hz to a few Khzs. He will probably have his hands full of oil or reaching into some awkward gap under the dashboard. Portable, cheap and isolated, will be higher priorities than feature rich and accurate. The Nano should be fine. Enough to verify there is a regular pulse train, which varies with engine speed and does not break down at high RPMs or high temperatures.

I have a DS2072 for measurement and difficult stuff. My Nano get's just as much use because it's so convenient. I can quickly do a sanity check, without having to clear bench space, plug anything in or even think too hard about it. Worse bit about the Nano is the firmware it ships with. The BenF firmware makes it much easier to use.

But yes, Toolman666 could do with a primer or two. Essential knowledge is setting X axis, Time per division (5ms to 50ms). Setting the Y axis, Volts per division (2V/div for 5V signal). Probe impedance matching (x1 or x10). And trigger setting, which is not difficult but about as difficult as it gets.

Hooking the probe calibration output pin is useful while finding your way around. Set the output to 500Hz and 50% duty cycle, which is about the right frequency setting for a crank sensor at idle.

HTH

ieee488: I don't know which manual you are looking at. I am look at the one the OP linked.

It quite clearly states on page 3, section III Major Functions Inbuilt Test Signal 10Hz~1MHz(1-2-5 stepping)

Yes. Test signal. It has a signal generator. That is not the bandwidth.

Why is it "scope snobbery"? There are loads of these little scopes out there with unethical sellers claiming much wider bandwidth than they have. If the actual bandwidth is good enough for you at that price point, great.

Was anything that I said incorrect?

Usually the crank sensor ia a inductive type with 3 or 2 wires (signal, ground and may have a shield). This kind of sensor gives a pulse every time a tooth passes in front of it. The problem is that in order to work it need the tooth to pass with a minimal speed, since it generates it's own voltage using the change of the magnetic field the metal (the tooth) gives. It generate a voltage that varies also with speed, going from 1v to 50v, both positive AND negative. Again, usually the crank gear have 36-2 teeth, which at 12000rpm of the engine gives 200rev/sec X 36= 7200Hz, so the analog sample frequency of the DSO nano V3 scope (200kHz) is fine for that The cam sensor generally is really a Hall effect sensor, so it just gives 0v or 12v as a signal, so just adjust the scope to run with 5v or 10v per division, should work for both sensors (5v works just fine here with an old osciloscope). Hope this helps....

It sounds perfect for this.