Digital oscilloscope project/kit

[RobWilson]

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

BUGGER ! 

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



Roy.

It needs a wee bit TLC Roy , there is a crack in one casing , switchgear missing , two levers to make and fill in the whitless marks on the table ,nothing that I can't fix  but saying that it does work . 

That there table is 500mm x 400mm ,it has an  8 speed 4MT power feed quill  , not a bad swap for my RF25 mill drill . 


Rob

[RobWilson]

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.....

Cheers Mate 

The hot air rework station seems fine to me John , but what would I know    , does the job , can't complain for the money 

I just need more practice 



Rob

[awemawson]

Can you not make a thing like the weighted pointer that I use for silver soldering - stand with long pointed bar pivoted and weighted to rest on the work and stop it blowing away in the flame - or in your case hot air gun ?

[wheeltapper]

Or you could just hold them with a pair of tweezers.

Roy.

[awemawson]

It's all to do with gaining an extra hand - tweezers use one up 

[wheeltapper]

How many do you need? One holds the tweezers, one holds the iron / air gun.
if you are using an iron you pre-solder one pad, then hold the component in place and reflow the solder, then do the other end with solder.

With a hot air gun you use solder paste.

simples.

Roy.

[PK]

 A deft hand on an iron is better for assembly, but hot air is essential if you are ever going to remove a chip with more than two solder pads.
PK

[wheeltapper]

Very true.
I managed to remove a 16 pin chip from an old board, no trouble.

Roy.

[awemawson]

I've done that with  16 pin surface mounts using a 50 watt Weller TC iron using low meting point solder 'additions' to keep it fluid long enough. Flood the leads with low melt solder, remove the chip with a cocktail stick, clean up with solder wick.

Back in the early days of 7400 series logic - all through hole of course - I used to salvage chips off boards by the simple expedient of putting a 14 or 16 pin i/c inserter clip on the victim, and flashing the back of the board with a blow lamp while pulling on the clip. Not recommended if you want to reuse the board though with care surprisingly little damage was done. The occasional plated through hole would come as well leaving the chip looking as though it was wearing trousers 

[hopefuldave]

Sounds like the IC "reclaimer" I saw who turned a blowlamp on the solder side then bashed the boards on the bench - 95% removal rate, and they *looked* fine...

Dave H. (the other one)

[DICKEYBIRD]

Just a quick post to say thank you very much to all who have contributed to this thread.  I read & enjoyed every word.  I never knew so many wonderful things are done by mere mortals in their own homes & workshops....with so little money!

Cheers to you one & all!

[Pete W.]

Sounds like the IC "reclaimer" I saw who turned a blowlamp on the solder side then bashed the boards on the bench - 95% removal rate, and they *looked* fine...

Dave H. (the other one)

Maybe I'm about to propound yet another urban myth but here goes anyway:                   

My understanding is that the flame (e.g. propane or paraffin) is a plasma so it's conductive.  There's little risk of electrostatic discharge damage    to the chips because, while they're in the flame, all their 'legs' are effectively shorted together. 

[awemawson]

Well certainly I don't remember any of the ic's being faulty after removal that way, and some were the early MOS memory chips that had little inbuilt by way of electrostatic protection. But it was mainly TTL 7400 series or the Mullard  FCHXXX or FCKXXX series equivalents.

[RobWilson]

 Evening Chaps 


I thought I would mess about with anouthe Bangood project tonight  , I welded up the wee power supply to use with the signal generator .



Not a bad board it dose have a few SMD parts , three fairly large inductors , noting the new hot air gun could not cope with 





The soldering welding is not the best a my solder paste had gone off  anyway I got the project  up and running with only one hitch  , some fool soldered one of the shottky diodes arse about tit .
Which causing the board to have no minus voltage  outputs  ,,,,,,,,,,,,,,,,,and made the buck convertor get a tad warm 



I must admit to enjoying troubleshooting my f45k ups  and here are a few action shots  of it and the signal generator working 





all gipping stuff lol .


Question for the more knowledgeable , the board has a 3.3v output  , I would rather have a 9v out put , is there a replacement for the 1117-3,3  smd voltage regulator that I can replace with a 9v reg ?

I have had no luck finding one ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,due to not knowing what I am looking for 


Cheers Rob   

 

 

[John Rudd]

Rob,
You may need to mod the board to get 9 v.....

Have you got a link to the kit or the schematic?

[RobWilson]

Hi John ,    I can't find a circuit diagram for this project  , I was just hoping that there was a 9v Reg in the same package I could just solder in place .



But I am  always up for madmodding lol


Rob

[John Rudd]

Rob,
What about a link to the kit you bought?

The little 3.3v regulator wont have enough juice applied to it to get 9v out...that is, the 3v reg will only have about 6v in to it to reduce its dissipation....so a drop in wont work
You may have to cobble something using the 12 v side.....

[John Swift]

Hi Rob

in the advert they say they don't provide a schematic !!! - no good for modders 

I guess the switching power supply generates some thing like plus and minus 18V

the positive SMP output  supplies the 78M12 and 78M05 regulators for the  +12V and +5V outputs
and the negative SMP supplies the 79M12 and 79M05 regulators for the -12V and - 5V outputs

the "1117"  3.3V regulator looks like is powered by the +5V regulator (78M05)

to add a 9V regulator you need to either tap into the supply to the 12V regulator or the 12V output

the 9V regulator can be a 78M09 or a LM317 adjustable regulator and resistors

     John
  PS

Do you had a photo showing the PCB tracks of the other side of the board

[wheeltapper]

Hi Rob.
I'm still waiting for my power supply kit to arrive, it was allegedly posted on the 30 Jan so where is it 

I've got the sig gen kit but I want to get the supply running before I build it or it will sit there and annoy me.

I built the frequency counter kit and that works OK ( even tho I said I wasn't going to get it )

I'm also thinking of getting this http://www.banggood.com/DIY-Aviation-Band-Receiver-Kit-High-Sensitivity-p-990306.html as I live near Norwich airport.

could someone look at the schematic of this receiver and tell me if I could connect the frequency counter to it to check the receiving frequency.
cheers
Roy.

[John Swift]

Hi Wheeltapper

 you need a frequency counter that the   displayed frequency can be off set by 10.7MHz
this avoids having do  the maths to work out what its tuned to

looking at the circuit the coil L6 , capacitor C14 and varicap diode D1  set the frequency of the local oscillator (part of U1) - this is what needs to be the input to the counter

the output of the oscillator is mixed with the signal you want to receive
the difference between the two has to be 10.7MHz to pass through 10MHz filter  fil1
and when amplified by Q1 and U2 pass through the IF transformer T1

D1 is the AM detector that resolves the audio signal to be amplified to drive the loud speaker or headphones

       john

PS

a frequency display like this -
http://www.ebay.co.uk/itm/50MHz-LCD-Frequency-Counter-Module-with-IF-Offset-Free-UK-Postage-/172103761140?hash=item28122efcf4:g:mKAAAOxyThVTXnoD

[wheeltapper]

Thanks John but I've just realised that it won't work anyway.
The receiver tunes from 118 mhz to 136mhz and the frequency meter goes from 1mhz to 50 mhz.  OOPS.

Oh well, back to he drawing board.

Roy.

[John Rudd]

You could always add a prescaler to the counter....

But that adds to the complexity of things.....

[RobWilson]

Cheers for the replies John R and John S 

I will look for a similar usb to 9v PSU  project  or maybe something to be powered from the 12v  supply on the board 

Hi Rob.
I'm still waiting for my power supply kit to arrive, it was allegedly posted on the 30 Jan so where is it 


Roy.

Hi Roy , I have had delivery times ranging from one week to 6 weeks    , it's a bit pot luck ,,,,,,,,,,,,,,,,,,,,,ooooh just remembered you do know things go a bit tits up in China for a fortnight this time of year , well the time you placed the order , its their NEW YEAR !  


  so you gave in and got the frequency counter  nice one  , well its your turn to lead me astray 

I live on the centre line for Newcastle airport so I have just ordered that Aviation band receiver 


Cheers Rob


 

[wheeltapper]

Oh dear, naughty me 

I haven't ordered mine yet, now I might wait until you build your's to see if it's any good.

Are we having fun yet?

cheers
Roy.

[RobWilson]

Are we having fun yet?

Wey aye 


Has your PSU kit shown up Roy ? 




I put the 0-30v PSU kit together last night 




I added the 12v cooling fan , there is a 24v output for a fan provided , I just swapped the voltage reg for a 12 v one I had .




All is good , no magic smoke  escaping 






NEXT ! 




Cheers Rob