hpr_transcripts/hpr2029.txt

Episode: 2029
Title: HPR2029: The DSO138 Oscilloscope Kit
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2029/hpr2029.mp3
Transcribed: 2025-10-18 13:31:18

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This is HPR Episode 2029 entitled the DSO 138 oscilloscope kit.
It is hosted by Enable and is about 21 minutes long.
The summary is Enable talks about building a DSO 138 oscilloscope kit.
This episode of HBR is brought to you by an honesthost.com.
Get 15% discount on all shared hosting with the offer code HBR15 that's HBR15.
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Hello, this is NY Bill and I thought I'd talk to you guys today about a electronics kit
that I recently got.
Sometimes I just poke around on the internet just because I'm bored and see what I can
find out there to build.
This kit came up just on a rent Google search.
I typed in an electronics kit and a couple of pages down.
There was this company called Sainsmart, S-A-I-N-S-M-A-R-T.
They seem to have quite a few different kits that you can build.
One of the kits in there that caught my eye was a DSO 138.
The DSO is a digital, well it's an oscilloscope kit.
It's a small little one board, well it's two boards actually, the LCD screen is up on
risers.
I'll put some pictures of the kit I got and I'll get into the linking in a bit.
I'm going to link to a board very similar to this but as the tail unfolds you'll find
out what I found out.
I didn't know what I was really going to do with it other than just enjoy building it
because I already have a scope and this scope is not particularly fast so I don't, you're
not going to be looking at high frequency signals with it but just the fun of building
it.
I thought maybe I'll get it but I put it off so I bookmarked it and I put it off and
I put it off and then one day I went back to it and I'm poking around researching the
board itself and stuff like that and I stumble over the schematics for it so that intrigued
me even more.
If while you're building you can look at the schematics that there's more learning
potential there and we'll get into that in a minute too because this one turned into
quite a learning while I'm still learning on it.
And I still put it off for a couple of weeks I didn't buy it.
This thing was only $22 but I was just like what am I going to build it and it's going
to go in a box with some of the other kits and I'll never use it.
Then I stumbled over that the fact that someone has made a 3D print so this doesn't come
with a case it would just be up on like plastic standoffs and you put it on the table
and use it like that.
So it's all exposed, the switches and the buttons you're just holding the PCB board
in your hand while you would be using it.
And I found that somebody had created that 3D print and it got me thinking oh my buddy
Ace fear maybe he can come to the rescue again with his 3D printer and make me a case
for this thing so that would be even you know it was just increasing the fun of you know
possibly building this board.
And then I thought well I can't just keep going up to Ace fear and say hey print this
for me, print this for me, print this for me.
So what I did was I ordered two kits $22 each you know just I just got two of them and
next time I was at the lug Ace fear usually sits right next to me so we just you know
chat the whole time and I pulled up the 3D print I go you think your printer will handle
this he goes oh yeah no problem yeah what we can do that and I go well if you print this
for me here you can have this and I gave him one of the kits and so it's become a like
a fun project for us you know the printing and the building of it why not share the fun
you know so let me see if I can pull up the specs on this thing and we'll go through
that a little bit.
Okay the analog bandwidth is 0 to 200 kilohertz so that's really not that much my big scope
over here goes to 100 megahertz so you're going to be reading pretty slow signals with
this thing sampling rate is 1 mega second per second.
Oh I'm trying to read the acronyms what one mega sample per second max sensitivity is
10 milli volts per division to 5 volts per division sensitivity error is less than 5 percent
vertical resolution 12 this is kind of boring isn't it recording like 1224 points built
in 1 kilohertz 3.3 volt test signal which I did read on my bigger scope we'll get into
we're going to keep getting into all this I guess and it has a save recall on the waveform
so it's really you know this is really down in the hobby level stuff if you're going to
get it just get it for the fun of building the kit and I'm sure you'll use it once in
a while but it's not going to be doing any heavy duty scope work the other neat thing with
this I've seen other scope kits out there and they're just like a gray scale LCD panel this
one has a color display I forget the size of it to I'm scrolling around well I'm going to
link to it in the show notes you guys can look it up I think it's like a 2.3 inch color display
once I got it built though it's really it's really a nice display it's bright very colorful
uh the kit that I got this same spark DSO 138 the surface mount parts are already mounted on
the board so what you're doing is you're doing the through hole resistors the through hole
capacitors you got put put on the switch there's some inductors there you know the different uh
the BNC connector I would say if you're not familiar with soldering you can get that kit and you'll
be fine there are kits out there where the SMD stuff the surface mount stuff is not put on as well
and if you've ever seen that it's very tiny stuff you know soldering pen with a very thin tip
and there's like a little technique and trick to soldering surface mount you know you might need
magnification and stuff like that so if you're new to soldering get the one with the and you're
gonna get one of these kits of course get the one with the surface mount parts already soldered on
if you want the challenge of the build you can get the one where you have to put the uh surface
mounts part yeah surface mount parts on as well which I wish I knew that was out there at the time
I would have gotten that one I didn't know there was multiple boards out there so what
I ended up finding out as I built it and I would go online and go to some certain forums I was looking
for uh information for this or that about it there's other boards that look exactly like this this
one's black and there's other boards that look exactly like this but they're red and that company
is J-Y-E-TEC I think I got that right yeah J-Y-E-TEC and from what I've read J-Y-E-TEC
developed this board you know did all the R&D and developed it and produced the board
and from what I'm reading this same smart company purchased some of the boards very early on and
like within two or three weeks had complete knockoff clones out in the marketplace and they're
even using the J-Y-E-TEC's firmware the splash screen that comes up when you start this
same smart this same smart is the J-Y-E-TEC splash screen so I mean China manufacturing electronics
in China it's like it's like the cowboy days over there so everybody's copying everybody I don't
know who to believe but I'm leaning towards the J-Y-E-TEC are the real guys so the board that I
link to in the show notes will be J-Y-E-TEC you guys if you're interested in this you can take it
from there I think it's like two dollars more and other things that I'm reading now is they've
come out with a new rev of this board and they're not releasing the firmware anymore so just to
try and keep an edge on the on the market they've cleaned up the waveform this the waveform
can be a little jittery on the older models so they've they've done something in the firmware to
you know try and get an edge back in the market and they're not going to release that firmware so
unfortunately the copying has closed up something that was pretty open so the building of it
is pretty straightforward uh you're gonna build things up from the the smallest component so I
trying to think back I did this I built this like oh three weeks ago no so it's the resistors go in
first here's another FYI the sane smart and I'm clicking the buttons while I'm talking the sane
smart kit none of the resistors are labeled so you can take this either way if you need to learn how
to read resistor color bands well you're gonna you're gonna learn because they didn't label anything
I believe the J-Y-E-TEC someone has written on the tape that holds the resistor together has written
what the values are so I mean I'm I've been around electronics for you know years in my you know
decades basically and even I messed up on the uh I'm looking at it now where was my R-26 and R-37 so
it was a 1k and a 10k resistor and when I tested it I read the bands and I tested it on my Keith Lee
and I just didn't move the decimal point or you know I just got those two confused so
later on in the build when I was going through troubleshooting now you know I ran at the trouble
here we go so later on in the build when I was troubleshooting I did find I had these two
resistors back so I mean even if you've been around this forever you can still make a mistake
like that but if it's going to be helpful for you to have the resistors labeled right out of the
package it's going to be the J-Y-E-TEC kit you're looking for after the resistors I'm trying to
think we I put on the capacitors which they're pretty all these components are pretty small this is
probably eighth watt resistors very tiny caps going that's just like a bunch of filtering caps
then what did I do actually I'm going to link to the instructions here they are you just go
right through first they have you do resistors and then the chokes I forgot about the chokes
yeah there's some inductors they look like a resistor but they're doing a different function
this is also a good learning kit too so you know you put in like a choke and then you might
realize what is a choke so you go look what a choke look go look up on google what a choke is
and then you're saying well what is this UH after that so you go look up what microhennries is
start learning about hennries on and on there's a cathode a crystal what you're basically doing is
loading the board up with the parts to have the shortest profile because when you flip the board
over to solder it if you put on the tall stuff first the short stuff would just fall off
and you'd get a mess so you just slowly build up you go onto the USB socket next and then the
tactile switches go in ceramic capacitors because they start now start things start to components start
to be a little taller on the board capacitors and the LEDs go in then you're doing the headers
transistors regulators here's another you know spot where someone could learn you know what's the
difference between this transistor and this regulator they look the same what is the function
you can look into what they're doing are they PNP NPN uh capacitor trimmers I put a capacitor trim
around there but it never had me trim it I don't know what it's there for uh usually a capacitor
trimmer picture it like a you know you have a volume knob you have a resist variable resistor which
is like a volume knob up and down and a capacitor trimmer is like a resistor except it's
changing the value of capacitance there's usually there's like fins inside metal fins that
don't touch each other but the more the fins get intertwined the more or the more they are separated
the more and less capacitance you get anyways I didn't have to at no point in the steps to
I have to trim the capacitors I'm looking at them right now two little green guys there's a power
inductor another thing I read while I was doing research some of the knockoff boards are coming with
the wrong size uh power inductor which is a one micro Henry and 0.5 amps so other some people
are running into they get the knockoff board and this the thing doesn't work right and they have
to end up ordering you know just one inductor from you know I don't know did you key or something
and you pay five bucks for shipping to get one little component so another gotcha there then you
put on the caps which are you know the big electrolytic caps the black black cans that like to blow
up on the top if you get a cheap one and then the power connectors and the headers and the BNC
connector and boom you've made an oscilloscope the sane smart I don't I have no idea if I'm saying
this correctly sane smart SA and I forget if I had to put the uh I forget if I had to put the
header pins on solder them no I think the LCD came with the pins already soldered on but the
JYA tech you have to put the header solder the headers on to the LCD screen as well I mean it's not
that it's a big deal no I did yep they were already they were already on and I had to solder the
uh the female socket header the receptor so this was like an afternoon I I had fun building it
and it was time to turn it on and I turned it on and the boot screen came up and I did see JYA
tech on the boot screen and then the scope screen shows up everything looks good I see a trace
right in the middle of the screen and then like 10 seconds go by and the trace just goes boom
right to the top of the screen it's it's off the screen you can see like a little fluctuation up
at the top I am still researching what this problem could be I'm thinking that uh the traces
controlled by a plus mode you know plus-minus voltage I forget what it was like six volts
anyways if like if you lost if the negative voltage went to four volts and the positive
voltage is still at six when they should be six and six your trace is going to go up so it's
interpreting what it's reading and running it through some uh amplifiers you know it's getting a
very low signal at the BNC it's running it through some amplifier stages and that's changing the
plus-minus voltage to make the trace go up and down on your screen mine just goes right to the top
when I did a review earlier there was an HPR I did where I was talking about the OON B35T
the multimeter and it came with the temperature probe and I mentioned in that episode that
I was recently troubleshooting something and thinking that one component was getting too hot and
making an IC chip go wacky that was this this build right here so confession time about what I
might have done wrong with this build so uh when I got it all built together I have a little soldering
caddy it's like uh it just holds the board for you and you can load up your parts on the front
and then flip the thing over and do the soldering so it's like a uh third hand helping caddy type
thing I got the board all built together it's on the caddy I went to my power supply it the
board wants nine volts so I dialed in nine volts and then I it's hard to explain it I turned the
board kind of over in the caddy and I hooked up to a negative point and I had the hot lead the
positive lead out of the power supply like between my middle finger and my ring finger and I was
using my thumb and my forefinger to clip the negative on and the red lead touched one of the
headers pins that can't comes out of the LCD and I heard and I knew you know I just sent nine volts
to some random spot on this board I could have burned anything out this I mean that's completely my
fault I hope if you build this kit it'll just work for you but as I say that I hope if you build
this kit it doesn't work for you because I've had more fun troubleshooting this thing if it
built and it worked it probably just would have been in a box on the floor never to be talked about
again but I had to really dig into this thing I got papers and papers in front of me I had to get
the board layouts I got full schematics I got I had to look into what the individual I see the
here's the U2 which is one of the ICs on the board it's a TL084 I had to figure out
what that chip was doing inside it and you know I found out there's four there's four sections
and it's non-inverting and inverting and where's the other one I should take a picture of this
it's got like highlighter all over it because I'm slowly using my meter to step through the power
supply stage and the filtering and then I'm slowly going through all the pinouts checking voltages
through the analog front end that's going to feed the IC chip that's going to do all the digital work
and I'm at a point now where I've troubleshot are we going to say that I did all I could troubleshooting
wise and I think that my problem is going to be digital so my next step for this board is I'm
they have the uh you are and uh really have you are you are in jtag they have you are in jtag
header pin so I think my next step is I'm going to have to flash this chip that that little voltage
surge that I sent through there might have just you know messed up some little logic gates somewhere
anyways that's where I'm at you can see I'm going to have pictures and you can see the build if you
want you can see the screen light up but mine is not working yet so I hope ASPIR fair is better
when he does his build because I I went to the lug this was a month after he I gave him his kit and
the 3d print file one lug we have our lug once once a month the next month he came back and he
printed two cases of various colors and he said here you know pick out your case color and pick out
your buttons so I picked all those out the next month I had had mine built and not working
and I go in and I go check it out I built it he goes why is it in a case he thought he did all
that work to make a case and I didn't even use it and I told him now I messed it up man it's how we
we were sitting there trying to troubleshoot it at the lug and we had the meters out in a different
scope and stuff like that so it's been a fun kit and if you're interested in electronic kits or
learning more about kits I would recommend this one I'm going to link to the JYE board which I think
is the legit one they're on Amazon they're like $24 I think they're like $2 more but
had I known that this was a knockoff I would have gone and got the legit you know the board from
the legit company so I hope that as I keep troubleshooting this I'll find out what the problem is
and maybe I can finish the build get it in the case and I can get another HPR out of that telling you
what I found what went wrong how I fixed it and then just showing the complete product in
Asphere's 3d printed case just a quick HPR to you know talk about this board and maybe some of
you might be interested I know some of you are into electronics and building kits and electronics
in general basically you don't have to just be building kits and all the time and I will link to the
I will link to all this paperwork and these schematics that I found and you know troubleshooting
guides and stuff like that so if you do build one of these maybe you can do a HPR as well and
let us know how your build went and I hope it went better than mine or if you want yours to break
too I can recommend how you can break it and then you can try and fix it so if anybody wants to
contact me I am nybill at sn.gov.nett.net for GNU Social Slice Identica nybill.gov.nett.net for
email and as always we could use the comment section at HPR if you want to have a conversation
okay until next time guys
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