Digital oscilloscope project/kit

[PK]

We have one of these at work http://www.peakelec.co.uk/acatalog/jz_lcr40.html
As I recall, it wasn't 'chinese cheap' but it works very well and we use it more than we thought we would.

[awemawson]

Yes I have one of those tucked away in a drawer. Extremely useful. Only irritation is that it's calibration period is obviously written into the firmware so it nags me to send it off whenever I use it!

[John Swift]

tried  the DSO138 power supply mod
with firmware 113-13801 -050 you don't get an improvement
unlike that as described at -
http://forum.banggood.com/forum-topic-61279.html
for the early version that's cloned using FW  113-13801-040

managed to buy 6 AA nicads for the Velleman K7105 'scope I built back in 2002
with no back light , the picture showing the trace of the test signal from the DSO138 is not great but shows the trace for comparison

     John

PS
RS Components do a slide switch that could be OK to mount onto a new front panel

 thought the 2 slide switches (sen1 & sen2)could be replaced by 1 rotary switch
but the rotary 4  pole 9 way switches I've found so far are several times more than the cost of the kit !

[John Rudd]

Hmmm...I guess what you pay for....

No point in buying a Mini if you want Ferrari performance...

[PekkaNF]

I wonder how well this kind of rotary switches would work?
http://www.partco.biz/verkkokauppa/product_info.php?cPath=2065_1046_1276&products_id=15706&language=en

Are there any reasonable quality rotary switches like used on scope voltage input stage? Probably someone has considered building simple specialized input amplifiers, bit like differential amplifiers or such. Really hard to build an amplifier that is good in everything, but not too hard to build amplifier that does one or two things good eneough.

Pekka

[John Swift]

Hi Pekka

the switches look OK - I assume they are break before make

twice I have resorted to making a custom switch using parts from RS Components


http://uk.rs-online.com/web/p/rotary-switch-shaft-assemblies/0327894/
plus
http://uk.rs-online.com/web/p/rotary-switches/0352193/?origin=PSF_428206|acc
or
http://uk.rs-online.com/web/p/rotary-switches/0352222/?origin=PSF_428206|acc

  an expensive solution , but it worked

    John

[PekkaNF]

Those "Wafers" are not silly money, but shaft and rest of it will add up. But they are higher voltage and probably lower capasitance etc.

Pekka

[RobWilson]

Hi, just a quick pic of my test board.


it's not too bad, at least the LED works.

Roy.

My SMD kit arrived today ,,,,,,,,,,,,,,,,,,,,,,,,,,,,F*&k me  those are bloody small components Roy 

They are going to take some welding  , 3.2 mm  7018 rods should do the trick 


Rob

[John Rudd]

Hi, just a quick pic of my test board.


it's not too bad, at least the LED works.

Roy.

My SMD kit arrived today ,,,,,,,,,,,,,,,,,,,,,,,,,,,,F*&k me  those are bloody small components Roy 

They are going to take some welding  , 3.2 mm  7018 rods should do the trick 


Rob

What about post weld heat treatment? Have you got a heat blanket to wrap the board in for stress relieving.....??

Sounds like you are all having fun....  

[RobWilson]

  I was planning on peening the welds to relieve the stress John .


My Buck converter power supply arrived a few days back , opened it up and it has surface mount components    , so a quick shop on Ebay fro some new gear ,

one has to buy new toys 




And some tackle to practice with .




WTF !



Rob

[wheeltapper]

Hi Rob.
yea, they are a bit titchy,  on that board the 0603 resistor is the smallest and that is what is on the scope kit, the frightening thing is,they come even smaller than that, at least three sizes.

funny coincidence, I just ordered an 858D hot air gun, different make to yours tho. got it off Fleabay.

If you are interested in a review see here.

 A different make again but the same thing.

make sure the chipping hammer is sharp before you start.

have fun.
Roy.

[RobWilson]

Hi Roy

Cheers for the youtube link  very interesting    they all look very generic , my one  feels and look  canny , not bad for the money , mains lead is a tad short .

http://www.ebay.co.uk/itm/331330745304?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT




You say the resistors  come even smaller 


I have put a fresh flap wheel on the grinder   

Rob

[wheeltapper]

I thought you'd like that, he has an SMD solder tutorial here.

&index=3

this is the hot air gun I ordered. http://www.ebay.co.uk/itm/371415508867?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

as far as I can see they all look the same.

Roy.

[RobWilson]

Nice one  Roy 

Question , How long  were you on soldering all those resistors ? 


and how do I know which way round the LED goes lol 


Rob

[wheeltapper]

Rob, I think it took me about 15 mins per column.

put 3 volts across the led an see which way it lights.......................only 3volts tho or........ once its all done you can put 9 volts from pad to pad.

if you hold the board up to the light you can see the trace.

looking at mine there is a little green mark next to the negative side. YMMV

that guy has some very interesting videos.

Roy.

[RobWilson]

Hi Roy

Cheers for the LED tip /info 



Aye just been watching a few of Dave's videos , very interesting and he is quite a character 


Cheers Rob

[kayzed1]

I have given up on mine now, i had the No trace on screen. I bought another screen kit and it is just the same...no trace but all other stuff is ok..just those two voltages that are not correct so binned it i went to the forum and one other person has asked the Q' with the same symptoms, and no answer from the mod or users, so bin it was.
Lyn.

[wheeltapper]

Rob. I received my hot air station this morning.
you said your mains lead was short, how short is short?
mine is a separate one that plugs in the back and it's 5 foot long.

It works well tho, I tried desoldering a tiny 16 pin IC and it came straight off the board.

Roy.

[wheeltapper]

Hi John, this is the one I got.
I ordered it on Tuesday and it arrived this morning.
http://www.ebay.co.uk/itm/371415508867?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT



Roy.

[sparky961]

Boy, I'm kicking myself that I hadn't bought shares in this company when it was first brought to light.  I've lost count how many kits have reportedly been bought as a result!

[PekkaNF]

I got one scope kit yesterday.

I was just eyeballing the PCB. Should have a cunning plan for the external rigger signal, but I want to assemble it as "standard" now. Display comes over it, not too much space for connectors or standoffs.

There seems to be some "optional" connectors: Like Mini USB and some for programming. Anyone used them?

[wheeltapper]

SNIP


My SMD kit arrived today ,,,,,,,,,,,,,,,,,,,,,,,,,,,,F*&k me  those are bloody small components Roy 

They are going to take some welding  , 3.2 mm  7018 rods should do the trick 


Rob
[/quote]

SNIP

Hi Rob.
We never heard how you got on with those SMD components.
You must have finished by now.

Roy.

[RobWilson]

   Hi Roy ,

 I have had a wee practice using the hot air gun and solder paste with  mixed results    , looking for a way to apply just the  correct amount of paste .

too much , wire feed a tad high 



looking a bit better , placement is a bit wonky 




I am using a stereo microscope to do the work , I think I need glasses 



I may practice a bit more this evening , things are a bit slow at  the moment as I am pulling my workshops to bits to make room for new machines  , like this wee beastie   










Rob

[wheeltapper]

You've got one upside down! all the pixies will fall out.

Nice looking drill press, is it a recon job or just chuck it in a space and use it?

posh microscope you have there,  all I've got is a MK1 eyeball and a magnifying glass.

Roy.

[John Rudd]

So opinions please on the hot air rework unit ?

Are they good, rubbish or something else?

Nice effort Rob, half the trouble is placing the little blighters and getting them to stay put.....

Then soldering them without dislodging.....