Bang good transtor tester DIY M12864 build

[PekkaNF]

On Rob Wilson's thread "Re: Digital oscilloscope project/kit "#18 is a nifty transistor tester he build from kit.
http://madmodder.net/index.php/topic,11145.msg130205.html#msg130205

I had to have one too.
http://eu.banggood.com/Wholesale-Warehouse-DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-wp-Uk-986954.html

It arrived two days ago and I build it yesterday. Was easy eneough and it works. Kit was good, but there were few things that annoys me. I could not find a parts list. References between circuit diagram and PCB were non existent. Felt really weird to "weld" componen on the PCB on silkscreen reference of the value. Makes troubleshootting bit hard if it were more complicated and more layers.

Really wished the insructions were better in structure. Engrish was parts funny, parts incomprahensive. That extended on user interface. E.G. function generator frequency mHz?

Anyway, seems to work reasonably good.

I'm at that point, where I think should I:
* Leave it as it is
* Make an enclosure and use it as a tranistor tester.
* Improve it a little and then make an different enclosure.


Few things got me curious, I hope I could get some answers.


1) How well this processor is protected on ESD and other cuties? All pins are pretty much connected without any ESD or OV proections straight to the processor. I could solder a subboard with TVS or such over auxiliary test point exits. Probably this would have some impact on capasitance range on lower end but I doubt.

2) Any thought about using and adaper to power it insted of battery. Specially if used as a function generator.

3) How usefull freguency counter input is? Incidently I did not recognize where that TP is connected on Atmega.

4) How useful function generator output is? It is not buffered or protected. But there are may ocassions a siple TTL signal is that is needed.

Thank you,
Pekka

[John Stevenson]

That kit is £14.91 in UK pounds
I just bought one from China for £9.67 with £0.33 pence postage so say £10 total and that was ready built and worked out the box.

http://www.ebay.co.uk/itm/201493269992?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I thought kits were supposed to be cheaper ?

[Brass_Machine]

The extra cost is for learning how to Solder (weld?) John.

Seriously though, I have been soldering for a long time, but have not done much SMD soldering. How are you guys doing it?

[Joules]

Quickly

[PekkaNF]

....
I thought kits were supposed to be cheaper ?

Yheah, but yours is like spotify - you have endure the special "F-generator"...I would get tired on Gordon Ramsey.

Seriously though, I have been soldering for a long time, but have not done much SMD soldering. How are you guys doing it?

SMD flux, 60w iron and still I avoid soldering it.

But seriously. Any ideas about the original questions?

Thanks,
Pekka

[seadog]

Hi Pekka, I've done some SMD replacement. The method that works for me is to use a liquid flux and very small gauge silver loaded solder. I flux the pads and then position the component, the surface tension helps to keep it in place. I then cut tiny pieces of the solder and place a piece by each leg (if it's an I.C.). Then, using a 12 watt iron with needle bit and a head visor, work my way work my way around the component. It's easy if you're patient. My first efforts weren't that good!

[awemawson]

Hot air gun works with the right nozzle

[PK]

We do a LOT of SMD rework and assembly.

To give you a feel for it, you know that roll of solder you have in your toolbox, or on your bench? Its probably a 250 or maybe a 500g roll and you've had it for years...
When we are making batches of product, we use about 1Kg of solder a day!

The tricks to do good SMD rework (or even hand assembly) are:

Preheat the board. Take it up to 50-80 deg c and (if you can) hold it there. It dramatically reduces the time you spend holding an iron or hot air gun on the job, locally heating a spot to 300+degrees. You'll find the PCB's last many more rework cycles and you can do things like remove small parts with a single tipped iron. Preheating can be as simple as holding the hot air gun on the back of the board until it gets too hot to touch before switching to the other side.

Use flux. Get a no clean flux pen and use it, not solder when putting a part back on. There was enough solder there before, so there's enough solder there now. The flux will let it wet onto the part.

[PekkaNF]

Nice info PK, thanks.

Does anybody read OP nowadays? Or does the formus shows only new posts on touchpads or what?

Pekka

[dvbydt]

So, yes I had to have the scope - no problems. I bought the one with pre soldered chips. Then the Component Tester but this time I bought the assembled board, like John S.

BUT :-

"I am a Bear of Very Little Brain, and long words Bother Me," Quoting  A. A. Milne.

How do I use it, everyone else seems to know. All the experts show components plugged into the ZIF socket - how do they find out where?
Eventually, like Poo Bear the light dawned. This board has the Mega328 computer chip (Same as Arduino) and has RAM, ROM etc built in. The software configures it as a three terminal tester. Components can be connected to any two of them - resistors, capacitors, diode and inductors. Transistors and other three terminal devices can be tested - magic!

The attachments show the ZIF socket. The figures are not a serial number but refer to the holes in the ZIF. Two parallel rows, any combination of the holes can be used 1&2, 1&3, or 2&3 or 123 for transistors. There are three pads on the board and three flying leads.

Very happy bear.

I hope that this might help other bears out there.

Ian

[dvbydt]

More fun

A long press on the black button brings up a menu and you can pick one of 10 sub functions. The only one I have played with is the function generator.
Photos attached.
The camera captured two scans, only one scan is normally visible.

Ian