$15 Oscilloscope!

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$15 Oscilloscope!

Postby Andrew Davie » Sat Jan 28, 2017 7:00 pm

I thought this might be of interest - a DIY oscilloscope kit for $15 (including shipping!)
https://www.aliexpress.com/item/DSO138-2-4-TFT-Digital-Oscilloscope-Kit-DIY-200KHz-Tester-1Msps-Bandwidth-Probe-Electronic-Production-Suite/32744875561.html
If you search YouTube and browse the various videos related to "DSO138" you will see that this is quite a capable device in the audio range - up to about 20kHz.
I've just bought myself one, and hope to resurrect my televisor sometime in the near future, using this as a diagnostic tool.
It's not going to be a perfect oscilloscope - but for $15 it's a great way for beginners to get something that functions and is practical for NBTV use.
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Re: $15 Oscilloscope!

Postby Klaas Robers » Sun Jan 29, 2017 4:33 am

Andrew, I think if you don't have an oscilloscope, this will do a lot for you. And for NBTV 20 kHz is high enough, so why not using this very cheap solution.

However, I have seen that although the horizontal time base goes to 20 kHz the resolution is much better. So you can see and inspect the wave form of much higher frequencies. Marvellous fro NBTV signals.

Then, later, at a certain moment, a real oscilloscope will come onto you path. Now and then they are discarded by companies ....... and you can have them for little. But not as cheap as this more modern solution.

Good luck with it.
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Re: $15 Oscilloscope!

Postby Andrew Davie » Sun Jan 29, 2017 11:19 am

Thanks Klaas. In fact I had an Oscilloscope - a Tektronix of some sort - but I gave it away to a young boy (about 12) who wanted to learn electronics. The young lad had plans to disassemble a CRT television, but I quickly put him off that idea (and warned his mother why, too!). Anyway, I wasn't using it and I had built my televisor. But now my televisor is long-dead (and not completed properly anyway). This "toy" oscilloscope looked to me perfect for NBTV use, so I thought I'd give it a go. I'm glad you have given it the tick of "approval", that makes it pretty clear that it's going to be useful enough for a NBTV build. Maybe the club shop should include it :)
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Re: $15 Oscilloscope!

Postby Steve Anderson » Sun Jan 29, 2017 8:17 pm

As I'm in the UK for the next couple of weeks I've ordered two of these devices, one just for the heck of it, the other to have a close look at what you get for fifteen bucks! (Including UK delivery!).

I agree with Klaas, on the surface it looks ideal for NBTV work. To turn it into an instrument it would only require a plastic case and perhaps extending the switches to be 'off-board'. It appears to only require a 9V 'wall-wart' to get it going or maybe a set of batteries, I'll have a look at the current consumption for that.

It mentions 'no solder', what they actually mean is it isn't soldered, you do have to do the soldering.

It's a shame they haven't included a link to the manual, but I expect it to have no external trigger, no external horizontal input or intensity modulation. So as provided it probably is not suitable as a NBTV display. But a thousand times better than having no 'scope at all.

More to come...

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Re: $15 Oscilloscope!

Postby Andrew Davie » Sun Jan 29, 2017 8:49 pm

Just a warning - unless you order and pay for express shipping, then "free shipping" is probably going to be 4-8 weeks :)
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Re: $15 Oscilloscope!

Postby Andrew Davie » Sun Jan 29, 2017 8:52 pm

Steve Anderson wrote:
I agree with Klaas, on the surface it looks ideal for NBTV work. To turn it into an instrument it would only require a plastic case and perhaps extending the switches to be 'off-board'. It appears to only require a 9V 'wall-wart' to get it going or maybe a set of batteries, I'll have a look at the current consumption for that.

It's a shame they haven't included a link to the manual, but I expect it to have no external trigger, no external horizontal input or intensity modulation. So as provided it probably is not suitable as a NBTV display. But a thousand times better than having no 'scope at all.



Here's the manual!... http://akizukidenshi.com/download/ds/jye/UserManual_138_new_s.pdf
Here's a plastic case with raised switches :) https://www.aliexpress.com/item/DSO138-2-4-TFT-Digital-Oscilloscope-DIY-Kit-DIY-box-Electronic-Learning-Set1Msps/32649448898.html

Amazing what you can do for US$15 (inclusive of postage) and still make a profit!
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Re: $15 Oscilloscope!

Postby Andrew Davie » Sun Jan 29, 2017 10:19 pm

Steve Anderson wrote:It mentions 'no solder', what they actually mean is it isn't soldered, you do have to do the soldering.


Actually, not quite true. Some of the kits ARE already soldered (badly, apparently). And as far as I can tell, ALL of them come with the SMD components already mounted.
So you will see some saying "soldered" or "no solder" or "assembled" - these may very well be already done.
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Re: $15 Oscilloscope!

Postby Steve Anderson » Sun Jan 29, 2017 11:26 pm

Andrew Davie wrote:Just a warning - unless you order and pay for express shipping, then "free shipping" is probably going to be 4-8 weeks :)

Oh! I didn't notice that. Never mind, my brother can ship them on to me when I get back to Thailand. Though I might see if I can change the order shipping method if possible.

Having a quick glance over the schematic, it should be quite easy to provide external trigger in addition to the internal trigger. External horizontal looks like a severe knife-and-fork of the software. Depending on the uC used I may have a bash at it. Ditto the intensity modulation, it all hangs on how the display reacts to it and its response time - probably too slow even for NBTV.

Steve A.

Just checked on the shipping issue - too much hassle - I'll leave it as it is.
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Re: $15 Oscilloscope!

Postby Andrew Davie » Mon Jan 30, 2017 12:21 am

Just found another one - "DSO Shell"
See http://www.jyetech.com/Products/LcdScope/e150.php for details. It's the new-improved DSO138.
Also on AliExpress for US$22 which is an equivalent price because this has a cover, of course.
Here's a sample unit... https://www.aliexpress.com/item/Digital-Oscilloscope-DIY-Kit-Parts-with-Case-SMD-Soldered-Electronic-Learning-Set-1MSa-s-0-200KHz/32784881907.htm
I'll grab one of these units, too, and report on it's effectiveness.
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Re: $15 Oscilloscope!

Postby Steve Anderson » Mon Jan 30, 2017 5:13 am

Having a look at the second (cased) version, it appears all that has been done is to extend the input voltage range which would be quite easy to do with the first version, given appropriate switches and resistors. Also they seemed to have tidied up the electro-mechanical aspects. Otherwise it seems much the same...at a first glance.

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Re: $15 Oscilloscope!

Postby McGee2021 » Mon Feb 06, 2017 5:21 am

I was recently antiquing for parts, and found an oscilloscope. I went to check if it worked, it didn"t, and they gave it to me for free! I went home to see what was wrong with it, and it was only missing a screw in fuse on the back cover!
John Logie Baird was obviously the man who sowed the seeds but did not reap the harvest.
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Re: $15 Oscilloscope!

Postby Steve Anderson » Mon Feb 06, 2017 7:36 pm

McGee2021 wrote:...it was only missing a screw in fuse on the back cover!

It's a good day when things like that happen. Sadly it doesn't happen often enough!

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Re: $15 Oscilloscope!

Postby Andrew Davie » Thu Feb 09, 2017 5:52 pm

My first DSO138 miniature el-cheapo oscilloscope arrived today; all the components loose in a small bag. The unit's main board is just 118 mm x 75 mm, give or take. The screen is a very usable 54 mm x 42 mm, give or take. It came with one instruction page for building, and one page as a user guide.

These are viewable at http://akizukidenshi.com/download/ds/jye/UserManual_138_new_s.pdf

OK, so my first job was to measure all the resistors and make sure I had everything. All the components were there, and correct. I just followed the numbered steps on the build guide. I'm glad I had a microscope handy and did this at work with our fine-tipped soldering iron, because it's really quite fiddly populating the circuit board. The SMD components came pre-mounted, but I had to put everything else on. It was straightforward, though, but took quite some time - about 3 hours all-up.

I made just one mistake - I put male headers where I should have put female ones, and I panicked and de-soldered. In actual fact, I could have fixed this error by just putting the female where the male was to go, and it would have mated OK. But anyway, I found that de-soldering headers doesn't go very well and I had to find a replacement 2-pin header (x2) which was easy enough, and after a simple diagnostic voltage check I jumpered a few points on the board to make it "live" and switched on the juice (9V).

Display comes on! Welcome screen! And then there's a trace. Hold my finger to the supplied alligator-clip lead (red side) and there's the trace showing something. Triggering is working! (auto, normal, single), and the inbuilt square-wave test signal appears to be displayed correctly.

So, 100% working first time. Very happy with that. The unit is of course just a $15 bare-bones thing, but I thought the assembly instructions were well done and easy to follow. The build quality looks great to me, and the screen is pretty damn good for the price (it's colour).

Beware, there are apparently a LOT of counterfeits out there, and often supplied with incorrect resistors, capacitors and/or missing bits. So, look for a genuine supplier I guess.

Anyway, now it's time to dig out my old televisor from storage and find a CD player from somewhere, and start to put some signals in and see what happens!
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Re: $15 Oscilloscope!

Postby Andrew Davie » Thu Feb 09, 2017 7:30 pm

Displaying a square wave before calibration.
IMG_20170209_192409.jpg
I haven't calibrated yet - so the square wave has rounded corners.
(2.34 MiB) Not downloaded yet
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DSO138 Oscilloscope + NBTV signal test

Postby Andrew Davie » Thu Feb 09, 2017 11:09 pm

My $15 DSO138 oscilloscope built this morning, worked perfectly first-up.
I spent a half hour or so learning how to use it, and make a short video of me analysing a NBTV signal, which is at https://youtu.be/L8MsEh3DEMY
You can see I got triggering working just fine, and signal hold, and scrolling to view, and resizing... it's a pretty neat bit of "toy" hardware.
It inspired me to dig out my sad old televisor (which doesn't work) and start to resurrect it. The first step was just to play some NBTV signals through a CD player, and see what they looked like on the oscilloscope. I filmed the fiddling I did with the DSO138 and it seems to be a really capable little device for the purpose of NBTV analysis/building. I could clearly see and understand the signal coming from the CD player as a NBTV format signal with appropriate voltages. At around US$15 delivered to anywhere in the world, I reckon this oscilloscope could really lower the barrier for those interested in having a tinker, but who don't have much equipment.
Maybe the clubshop should sell/promote it?
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