Mini Nano ARM DSO201 Handheld Pocket Size Digital Storage Oscilloscope

[Paul Lockwood]

Hi

I'm sure that the more experienced who see the subject title may already be saying why post about this rubbish.
However I'm fairly new to electronics and I know you get what you pay for and I would guess that most people wouldn't even look at an Oscilloscope that wasn't 3 figures in value if not heading towards 4 figures.

Never even used an Oscilloscope before so I have no idea on what the limitations on this would be.

In plain English terms for someone who may well be lost with the first thing you say could someone tell me what use I could use the Item for and where I would hit the limitations of the device.

I've copied the specs over from one of the sites I could see them on.




SainSmart DS0201 is a pocket size digital storage oscilloscope fulfills basic electronic engineering requirements. It is based on ARMCortex™-M3 compatible 32 bit platform, equipped with 320*240 color display, SD card capability, USB connection, and chargeable batteries. Weighs only 60g! Portable Digital Oscilloscope DIY Kit provides waveform viewing, pocket size and over 2 hours battery operation.

Features

* DSO NANO Hardware 1.6 + Paul's Firmware 1.5
* Super portable and lightweight
* 2.8" color 320*240 display
* Basic 1Msps sample rate with 12bit resolution
* Various measurement markers
* Various trigger mode
Specifications

Display: 2.8″ Color TFT LCD
Display Resolution: 320×240
Display Color: 65K
Analog bandwidth: 0 - 1MHz
Max sample rate: 1Msps 12Bits
Sample memory depth: 4096 Point
Horizontal sensitivity: 1uS/Div～10S/Div (1-2-5 Step)
Horizontal position: adjustable with indicator
Vertical sensitivity: 10mV/Div～10V/Div (with ×1 probe)
0.5V/Div～10V/Div (with ×10 probe)
Vertical position: Adjustable with indicator
Input impedance: >500KΩ
Max input voltage: 80Vpp (by ×1 probe)
Coupling: DC
Trig modes: Auto, Norma, Single, None and Scan
Functionalities: Automatic measurement: frequency, cycle, duty, Vpp, Vram, Vavg and DC voltage
Precise vertical measurement with markers
Precise horizontal measurement with markers
Rising/falling edge trigger
Trig level adjustable with indicator
Trig sensitivity adjustable with indicator
Hold/run feature
Test signal: Built-in 10Hz～1MHz (1-2-5 Step)
Waveform storage: SD card
PC connection via USB: As SD card reader

Package

1x SainSmart DS0201 Oscilloscope
1x Probe
1x USB Cable
1x Manual
1x Flannel bag

 

[(*steve*)]

They're kinda cute. They have the advantage of being isolated from ground which can be useful at times. They also fit in your pocket.

However, they're also pretty noisy, inaccurate, and very low in bandwidth. For audio frequencies, they're probably fine. The controls are also pretty fiddly and it can take a while to change settings.

Just remember to use it regularly enough that the battery doesn't go dead flat.

Sainsmart is just a cheap Chinese distributor. Look around, you may be able to get a better deal. This device is open source hardware.

 

[Paul Lockwood]

Thanks Steve

It probably rules that one out then.
Is there a budget scope that would be worth buying?
Not really knowing much about them I guess I'm looking at using it on Arduino projects initially but at an extreme may need to connect to 240v in the future if I'm brave enough to go that far.
Also know nothing about bandwidths.

I've also spotted this on eBay http://www.ebay.co.uk/itm/Velleman-..._Measurement_Equipment_ET&hash=item35dc96a162
which is getting towards the upper budget I'd be happy to pay as long as it was equipment worth spending money on.

 

[(*steve*)]

That's got a 40 times better sample rate and is nowhere near 40 times the price.

The fact it's not open source means that it may not have as many features, but it's probably a lot nicer.

The DSO201 may be fine for measuring arduino outputs. As long as you are not having them change state more than about 100,000 times per second you'll be pretty good. Remember that 1 million samples per second means that what you see on the screen is only the state at each μs. If an output is on for 0.5μs and off for 9.5μs then you may not see the on pulse at all, and if you do, you'll see it on for 1μs.

The other device measures 40 million times per second, so it can spot pulses as short as 25ns (or longer pulses with an accuracy of 25ns)

 

[Paul Lockwood]

Thanks again Steve, most appreciated these quick replies.
Just taken a look at a video on the HPS10 at

For it's price can you see anything that I may not be able to do with it as a newbie?
What does the bandwidth up to 10MHz actually mean? Would I ever need bigger?

Sorry for these silly questions.

 

[(*steve*)]

It looks pretty interesting for a handheld device. If you want to buy a spare and send it to me, that would be fine.

10MHz is a low frequency for a desktop instrument, but probably fine for beginner use on circuits that don't use high frequencies.

As an example, it would not be useful to look at the 16MHz clock of an arduino, but would give you some idea that the clock is running if it were 8MHz. (at 8 MHz there would only be 5 samples per waveform, so you could not be sure of the shape or exact amplitude). As you get down to 4MHz, with 10 samples per cycle you start to get a better idea of the shape of the waveform.

With an analog scope, bandwidth is quite simple. it is the frequency at which the input signal is displayed at half its amplitude. (it's actually more complex than this because a typical signal will include components of different frequencies, all of which will be attenuated slightly differently when they are near or exceed the bandwidth of the scope.

With a digital scope you need to add to this errors due to sampling. if the scope measures the signal 40 million times per second then it will be unable to see what happens between the samples. This becomes a problem when important parts of the signal change more rapidly than that. If you have a signal at 10MHz (draw a sine wave) it will have 4 points between the start of one cycle and the start of the next (the start of the next will be measurement number 5. Mark these points then draw straight lines between them. That is perhaps what the scope will show. It looks like a triangular wave. But this is the best it can be. Assume the points are taken with a small offset, or that there is one fewer or one more. Statistical techniques can improve this, but not on a cheap instrument.

 

[KrisBlueNZ]

It looks like it's only single-channel, and that display is tiny and pretty low-resolution. Would he get better value for money if he bought a second hand analogue scope?

 

[(*steve*)]

That's a good point. These devices are only a good buy if portability is a high priority.

The same money as this will get you a much better second hand analog scope.

 

[Paul Lockwood]

Thanks for all the replies.
The thing that I am having problems with is that I don't know what is a good spec.
I can't list the 50 cheap scopes here on eBay that are going second hand.
Should I be looking for 10 / 20 / 100 MHz bandwidth, dual channel?
Having never used one it is hard to know what is a good bargain and what would be just as bad as the items I've listed.

 

[Gryd3]

Thanks for all the replies.
The thing that I am having problems with is that I don't know what is a good spec.
I can't list the 50 cheap scopes here on eBay that are going second hand.
Should I be looking for 10 / 20 / 100 MHz bandwidth, dual channel?
Having never used one it is hard to know what is a good bargain and what would be just as bad as the items I've listed.

I'm no good with prices on these, but avoid single channel.
Having a dual channel is ideal, as it will allow you to do things like comparing input/output signals. There are more uses, but thats the first things that comes to mind. Of course, more bandwidth is better as well... but there is such things as overkill. Do you have a budget?

 

[Paul Lockwood]

I initially started looking at the £40 pocket model as per the thread title, then listed the handheld at £80 which I still may be able to get cheaper.
Ideally would like to keep below £100 delivered if possible and as low as possible especially as it may only be something I rarely use.

 

[(*steve*)]

I would be looking at a second hand dual trace analog scope. The bandwidth should be 20MHz or greater.

Without experience you'll need to look for one from somewhere that provides a guarantee that it will be in working condition.

We might be able to give you our opinions of the source of on-line.

Edit: Importantly, a second hand scope needs to have probes and an instruction manual available. Too can buy probes, but having to do so will make the scope very hard to test. Manuals are available on the internet for many models, check before you buy if one will not be included.

 

[Paul Lockwood]

Just to give you an update I've gone for the Velleman HPS140I.
Before you all slate me on a bad buy here are a few reasons why I decided in the end.

• Got a sealed new boxed unit for £65, my local store sells these for £120
• Never used an oscilloscope before and even with it's limitations at this price thought it would be a good start
• Much better buy that the original item that I had created the thread for and only an extra £20
• Was very weary about buying a second hand scope especially as my knowledge of these is nil
• The I version comes with the scope leads
• Do like the idea of a portable unit as it will be to and from my office and home to use as I dabble with electronics, plus I don't have a bench or workshop at home so would need to pack it away after each use.
• Buying a portable item at a low price even with its limitations will get me going and increase my knowledge. If I stick to it and need something better in the future I will know what I'm looking for and will know that what I spend my money on will be worthwhile and something that I need.

I'd like to thank everyone for their replies as it has been most helpful. It's great forums like this that really gets us newbs moving along.