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Topic: PNP transistor in H bridge not closing (Read 832 times) previous topic - next topic

lukasz_b_g

Oh, I know that I could spend a few bucks and some robot would make it for me, but I wanted to learn how to make one. It was more about the experience than the finished product :)

So then I'll slap some radiator on, and hopefully it'll continue working.

Jiggy-Ninja

Still quite big!
I'm working with MOSFETs quite literally the size of a grain of rice, SMD devices, yet able to switch 5-6A.
SOT-23s? My biggest problem with those is holding them. It's way too easy to twist the tweezers a tiny bit or use just a wee bit too much force and then pyooh! off they fly into the ether, never to be seen again. Now I use reverse tweezers so that they're held with a consistent grip and I don't have to apply the force. It's much easier.
Hackaday: https://hackaday.io/MarkRD
Advanced C++ Techniques: https://forum.arduino.cc/index.php?topic=493075.0

TomGeorge

SOT-23s? My biggest problem with those is holding them. It's way too easy to twist the tweezers a tiny bit or use just a wee bit too much force and then pyooh! off they fly into the ether, never to be seen again. Now I use reverse tweezers so that they're held with a consistent grip and I don't have to apply the force. It's much easier.
You need a bib, like a baby's that clips to the edge of the bench, any bits flying towards  you land back on the bench.
I've seen a watchmaker  and a jeweller using them.
My grandson had better watch out, I might grab his.

Look at all the dropped components you could catch in that!!!!!!

Tom..... :) :) :)
Everything runs on smoke, let the smoke out, it stops running....

wvmarle

SOT-23s?
Exactly. I also got some 5-pin SOT-23s (a regulator), those are really impossible to do by hand. The pins are way too close together.

For an experimental project I just ordered a set of PCBs, 8.5 mm diameter circular. Gotta solder a few through-hole and some 0603 resistors on that... Gonna be fun :-) Maybe I should get a bib like that. Gotta keep it in mind.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Jiggy-Ninja

#34
Jul 17, 2017, 08:42 pm Last Edit: Jul 17, 2017, 08:43 pm by Jiggy-Ninja
Exactly. I also got some 5-pin SOT-23s (a regulator), those are really impossible to do by hand. The pins are way too close together.
The hell they are!

I have a secret weapon though. Knife tip!



Put a small amount of solder on one all the pads of one side, then put the device in place and use the edge to reflow all the pads. Once it's in place, put a little solder on the face of the knife and swipe it on the other side to solder the remaining pins. Don't forget flux!

The knife tip is my current favorite, even for general use.

I must confess though, before I got the knife tip the one SOT-23 I tried to solder with a small chisel type was dreadful.
Hackaday: https://hackaday.io/MarkRD
Advanced C++ Techniques: https://forum.arduino.cc/index.php?topic=493075.0

wvmarle

That requires a PCB, while I was soldering it on a protoboard (the SOT23 MOSFET just fits in between three holes). Good enough for prototyping and testing, I'm letting the fab do the actual PCB assembly. Costs a bit more but saves me a lot of time and effort.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Wawa

I also got some 5-pin SOT-23s (a regulator), those are really impossible to do by hand. The pins are way too close together.
I have no problems soldering SOT-23 by hand.
Easier with paste and hot air though.
Leo..

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