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GB: A Simple Discrete Current-Mirror IV Converter, à la AD844

Amazing Vunce ��. Your soldering always inspires me to up my game. I recently got some Cardas and Kester eutectic to try and now get nice shiny joints. I just need to work on my smd alignment.
What technique did you employ here? Iron or smd re work gun/hot plate?

I finally have my Susumu 10R that were on back order so i intend to start my build soon.

What psu are you thinking of using Vunce?
 
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Thanks Fellas 🙂
Correct Jim, basic hot plate and pan for preheating, then use hot air from the top.
I do go over the work and touch up with a fine tip iron. Cleaning the flux residue is handled with 90% isopropyl, Kimtech wipes and soft bristled brush.
Good tweezers, plenty of light and head magnifying gear is a must! Patrick is right, I used to avoid SMD like the plague, but I thoroughly enjoy the process now.
As far as psu goes for the CM I/V boards I’ve got a couple ways I can go. Probably try my DC/DC converter LDO regulator psu first. I’ll post build progress on the AD1862 dac thread.
 
I had a practice session this afternoon, soldered up the spare parts/PCB supplied by Ripster. I think reasonable for hand soldering and if I can manage it anyone can!

jGQoJny.jpg


Sorry the picture's not that great.

Time to order the resistors and see if I can get some boards fully sodered up.

BTW, I did this using thermally stable solder past dropped onto each pad with a very fine nozzle. I carefully place the part onto the pads and clamp it in place with a piece of wood (I used a kitchen match that I tapered) while I touch each pad/leg with a fine tipped iron. Seems to work for me. Oh, and I use high magnification googles while I'm doing it.
 
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if you use plenty of flux, you will find that you dont need to place it on every pad and hot air, or a cheap hot plate will sort out the soldering for you, no need to clamp anything, surface tension takes care of everything. Nice job for a first go hand soldering, but I do think people make this harder for themselves than it needs to be. If I was to be picky, You could use to wick off a bit of the solder, theres is a bit too much IMO.

ahh, I only just caught Patricks post. ok disregard the above, if the pads are not suitable for reflow, dont use reflow.

To answer the question about reflow/hot air on 2 sided boards though. for DIY reflow, without specialized wave soldering machines etc, you would typically design the PCB to have most of the difficult parts on one side, mostly the top (assembly) side and the bottom is mostly solid GND pane, with minimal passives, or easier to hand solder parts.
 
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Thanks Jim.

Nice job for a first go hand soldering...

Thanks, though it's not my first smd soldering, just the first with such tiny parts. I've hand-soldered larger parts a few times and hot-air reflowed a few boards. My matchstick technique works for me and means I need only a very quick touch of the iron on each pad.


If I was to be picky, You could use to wick off a bit of the solder, theres is a bit too much IMO.

Yes I could, but IMO that would mean reheating the parts unnecessarily, increasing the risk of something failing, so I'll settle for having a little too much solder.

Anyway, the passive parts for two pairs of boards are on order and should be here later this week so I can have a go at soldering a pair of fully populate boards soon.
 
I use SMD tweezers instead of match sticks.
They are not expensive. See attached.

While hand soldering is OK with a bit more solder, there should not be so much solder to completely submerge the gull wing legs of the SOT23.
They are like that to allow for some flexibility to survive thermal stress.
By submerging them with too much solder, they might end up getting too much stress and will break near the case in long term service.
A reliability risk.
So I do use solder wick to suck off excess if I have too much solder on.
You can judge by looking at the package sideways with a magnifying glass.
The top half of the legs near the package should be free of solder.


Patrick
 

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Thanks Patrick.

I have tried tweezers but find my matchstick better personally because I just need to apply a constant downward clamping pressure once the part is positioned correctly whereas with tweezers I find the gripping and positioning coordination more difficult.

I'll try to use a little less solder paste next time and try to avoid the need for reheating to use a solder wick.
 
Nice and quiet this morning so I set about soldering up my GB boards. Not perfect, a few squiffy parts but I'm reasonably pleased with the results - to think I used to avoid smd soldering like the plague. I guess I'll have to build a DAC to install them in now - I actually plan to pick up my AD1862 project again.

Y6be2WL.jpg
 
Hi Patrick. Are you able to supply a mechanical drawing of the I/V board - I want to include the option of plugging the board onto a DAC board using header pins/sockets. I'm interested in the coordinates of the In, Out, Gnd, +Vs, -Vs and 0V pads from the board's point of origin. I would normally get the coordinates using a Gerber viewer and I've also checked the holes against a 0.2in matrix prototyping board but they don't align.

Thank you.