Narrow-Bandwidth Television Association

Thanks for the demonstration. The oscilloscope triggers very fine and gives good rendering of the wave forms. I think it will help you to resurrect your NBTV monitor. Now you can see what happens with the signal on its way through the circuits.

Good luck!

For $15.00 you can't sniff at that result!!

Steve A.

Mine have been shipped apparently, but then my brother needs to forward them onto me here. So a while yet I guess...

Generally, working without any form (however simple) of oscilloscope is like going back to the dark ages where we didn't have mobile phones (smart or otherwise) or the Internet. How in the heck did we conduct business in those dark and dank ages? Somehow we did.

Getting into any area of interest in an electronics based subject is going to require 1) A multi-meter, a few quid from Maplin in the UK, 2) Maybe viewed as a luxury, an oscilloscope. It can be a steep learning-curve at first getting to know the machine, but believe me, after a while without it you'll feel like your right arm has fallen away.

This US$15.00 version is an ideal starter, it has its limits of course, but it's far better than nothing! When my kits arrive I'll do some form of review of it, unless someone else beats me to it! Perhaps Andrew has already done so...

Steve A.

I'm glad you offered to review it, Steve - I was going to do so but I would much, much rather you cast your eye over it.
It's been nearly 10 years now since I last used an oscilloscope in anger, when making my original televisor.

On that matter, I hooked it up to power today and sparks came out - literally! I'm going to start afresh - old faithful is an amazing bit of circuitry - being actually none at all - all components joined together on breadboard by snipped-off resistor wire and a few other bits and bobs. I have to laugh. I'll be a bit more meticulous this time.

So Steve - please, would you kindly take charge of a review for the journal?
Thanks!

Certainly Andrew...when they turn up that is! It may be a while yet.

Having viewed the circuit in the meantime, it's basic and straightforward. The majority of the magic is done in the micro.

It does have an input impedance of approximately 1M so a conventional divide-by-ten 'scope probe can be used to raise the impedance to 10M and allow for higher voltages to be viewed. I can't find any reference to bandwidth, I wouldn't expect much more than a couple of hundred kHz - but you never know. This is usually more than enough for analogue NBTV work and slower logic circuitry.

Steve A.

Actually I've found the specs...200kHz, quite a good guess if I may say so!

There's also a USB and a UART connection with no reference that I can find as to their function...unless I've missed that too!

It appears that the USB port can be used with their version of a PC oscilloscope, details here:-

http://www.jyetech.com/Products/105/e105.php

Steve Anderson wrote:I can't find any reference to bandwidth, I wouldn't expect much more than a couple of hundred kHz - but you never know.
There's also a USB and a UART connection with no reference that I can find as to their function...unless I've missed that too!

Yes, 200 kHz good figuring. THere's a video on YouTube feeding it variable frequency signals and it started to break down about 230 kHz or so. The USB is as far as I'm aware for "future capability" i.e., unused. You can leave it off. The UART is for upgrading the firmware, I think. Mine came with the latest so I haven't bothered playing with that.

I note on the JYETECH web-site that there's quite a few fake versions out there. They have a guide to identifying fake products, there's also quite a lot of postings regarding fakes on their forum. Who to buy from and who not.

http://www.jyetech.com/index.php

Steve A.

Steve Anderson wrote:I note on the JYETECH web-site that there's quite a few fake versions out there. They have a guide to identifying fake products, there's also quite a lot of postings regarding fakes on their forum. Who to buy from and who not.

http://www.jyetech.com/index.php

Steve A.

Yes, likely that many of the AliExpress ones are fake. The first one that I got was from BangGood (about $20) and they are supposedly a genuine supplier.
Even the fake ones are likely to work OK - but at such a cheap price it would be best to support the original company.

Well, the DSO138 had some small part to play in resurrecting my original televisor. It's working!

https://www.youtube.com/watch?v=eoATwxbWFhI

I plan to scavenge it for parts for a new build, as it's quite embarassingly messy and I never did get the speed control working properly. Here I'm just doing a manual synchronisation. The picture still looks pretty good though. It shows, I guess, that the DSO138 is useful. I found a few broken solder joints when tracing the signals in my really rather bizarre bit of electronics craftsmanship. Very happy to have it going again, but have ordered new boards from the club shop and just scouting now for an el-cheapo soldering station.

Hi there,

I bought the kit and started to assemble . There are several small surface mount devices to fit then I looked on eBay and for a few wonderful British pounds someone was 'knocking them up' in his shed so I bought one and it works a treat. I abandoned the original and if anybody wants it its yours for free. Surprising what you can do with such a little device. The switches tend to be a little 'fiddly' but for someone with limited access to an oscilloscope either at school or work it is a wonderful little device. We need to nurture and support youngsters coming into the industry.


Regards Chris Lewis

acl wrote:Hi there,

I bought the kit and started to assemble . There are several small surface mount devices to fit then I looked on eBay and for a few wonderful British pounds someone was 'knocking them up' in his shed so I bought one and it works a treat. I abandoned the original and if anybody wants it its yours for free. Surprising what you can do with such a little device. The switches tend to be a little 'fiddly' but for someone with limited access to an oscilloscope either at school or work it is a wonderful little device. We need to nurture and support youngsters coming into the industry.


Regards Chris Lewis

Since purchasing mine, which came as an unbuilt kit *except* it already had the surface mounted components installed, I've become aware of many kits available for just a few $ more (say, US$18) which have all parts installed/soldered. Given it took me 3 hours or so to solder, this is pretty much a no brainer next time I buy one

Not the same one but £15.39 eBay


http://www.ebay.co.uk/itm/Assembled-DSO ... 2348927773


Regards Chris Lewis

I must say I'm tempted. O.K., £15.39 is a bit more than $18, but, being in the U.K., at least I wouldn't need to faff around with international shipping. I just hope that by "welded" they mean soldered! The former doesn't bear thinking about.

Given that the "welded" version is only about £2.50 more than the kit, the latter is only of interest to those (masochists?) who specifically want the fun of assembling it. For just under an extra fiver they even supply a case.

Dave Moll wrote:I must say I'm tempted. O.K., £15.39 is a bit more than $18, but, being in the U.K., at least I wouldn't need to faff around with international shipping. I just hope that by "welded" they mean soldered! The former doesn't bear thinking about.

Given that the "welded" version is only about £2.50 more than the kit, the latter is only of interest to those (masochists?) who specifically want the fun of assembling it. For just under an extra fiver they even supply a case.

I got keen when I saw the kit and bought at US$15.68
The SMD components (about 3) were on-board, but all the rest took me something like 2 hours or more to mount.

Since then I've spotted assembled kits for something like US$17 and I would go that route next time.
e.g., https://www.aliexpress.com/item/DSO138-2-4-TFT-Digital-Oscilloscope-1Msps-Probe-Analog-Bandwidth-Welded/32741512381.html which specifically says it's soldered arleady. Though, warning, I have read somewhere that someone thought the soldering was poor on one of these.

But before you spring for one of these, there's a newer slightly more capable version for a few bucks more. Same manufacturer. I'm waiting for mine to arrive...
The DSO "shell" at around US$22.60 - https://www.aliexpress.com/item/Digital-Oscilloscope-DIY-Kit-Parts-with-Case-SMD-Soldered-Electronic-Learning-Set-1MSa-s-0-200KHz/32783300788.html - not assembled, though

My 2nd DSO138 arrived yesterday - this one was "fully assembled".
It did not work. Not well, anyway. I powered it on and the screen was solid white. I tried again, and it booted OK - but after a few seconds the display started getting corruption - lines and dots, etc. The LCD itself was kind of dangling loose - the sticky/tape holding it to its board was not working well at all. I played with it a few times, while pressing down on the LCD but still the corruption. So, I flipped it over and redid all the solder points on the back - it did appear to be reasonably well soldered, except for the (unused) USB port which may have a dodgy connection. After doing the resolder, still had the display issue. So I got a hot glue gun, and placed glue around the sides to hold it firmly down on its board - and voila - working perfectly. Additionally, the adjustment capacitors C4 and C6 seem to work, which is not the case on my self-assembled one.
I have tested with a 10x probe, and got pretty good adjustment on the inbuilt square wave - so this will probably be my main unit for now.
One other thing - the serial/key indicating genuine product was NOT present, so this was almost certainly a fake/clone. Software version is one release out of date, but works well.
Just thought I'd report my experience. The "genuine" one I self-built was purchased from BangGood - and this fake one from AliExpress.