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Protonerd / FX-SaberOS

System code for Arduino based Lightsaber replicas for DIYino family boards
Creative Commons Zero v1.0 Universal
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Mosfets #30

Closed FatherCool closed 4 years ago

FatherCool commented 6 years ago

Ok guys what mosfets are you using? Part codes would be nice! The ones I have are not correct.

DRagonenko commented 6 years ago

bd139

FatherCool commented 6 years ago

But thats not a logic level Mosfet its an NPN transistor and only has a max collector current of 1.5A. To run my rgb tri cree with the colours in parellel it needs to be able to handle 3A minimum as I am driving each die at 1A each.

I am now looking at an STP55NF06L which looks to have the right spec for logic level activation of high power circuits.

Max Vds 60V Max drain current 55A Vgs(th) min 1v, max 1.7v, breakdown 16V.

FatherCool commented 6 years ago

Actually I am in error as each led has its own mosfet therefore each only needs to take 1A.

DRagonenko commented 6 years ago

irfz44n

FatherCool commented 6 years ago

Ok mosfets sorted but how the hell do you guys solder them? In the breadboard they work great. As soon as you solder them into copper strip board they no longer work properly. There is no contamination across copper paths and all solder joints done well and fast. However take them back out amd stick them in the board and works ok. Agghh. I have also managed to kill 5 mosfets that no longer work at all. It seems that even 1 or 2 seconds on the pin with the iron and its toast!!

jbkuma commented 6 years ago

I'm not sure why you are having problems, maybe you need to use a hotter tip for shorter time?

On Dec 27, 2017 10:03 AM, "FatherCool" notifications@github.com wrote:

Ok mosfets sorted but how the hell do you guys solder them? In the breadboard they work great. As soon as you solder them into copper strip board they no longer work properly. There is no contamination across copper paths and all solder joints done well and fast. However take them back out amd stick them in the board and works ok. Agghh. I have also managed to kill 5 mosfets that no longer work at all. It seems that even 1 or 2 seconds on the pin with the iron and its toast!!

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FatherCool commented 6 years ago

I don't think so. I was using about 350 degrees last night but was having trouble with godforsaken lead free solder so that may have been an issue. Today I used leaded low melt which made a perfect joint in about half a second. Very puzzled and obviously nervous of making any further boards.

Protonerd commented 6 years ago

Are you sure you are not soldering on a powered board/system? Best way to kill mosfet is when poking around them with a metallic object while connected to battery/other power source. If you accidentally short drain and source, it will instant kill them.

FatherCool commented 6 years ago

Very sure. I have to hold the wires on a battery to connect it. I can't solder with those in my hands! ;)

FatherCool commented 6 years ago

Actually I wonder if I am leaving a charge across the internal capacitor of the Mosfet after the initial test? Not sure if that would make a difference?

FatherCool commented 6 years ago

Well I have just tried soldering these again and ended up with a none working set, again. The joins are good the iron isnt on for long and yet the mosfets leak and stay on slightly even when they are supposed to be off. I tested them with a multimeter prior to fitting, fine, after fitting, not fine, after removing from board, fine again. I am seriously puzzled. I can only think that it is due to flux contamination or something so just bought some different flux. I will try again tomorrow and report back. This is frustrating as the saber works great apart from this!! Maybe I need to brush up on my force powers!

FatherCool commented 6 years ago

Turned out to be the flux. changed to a different brand and all is well.

ec-cts commented 6 years ago

Finally, what mosfet have you used that do not give you problems?

Regards,

FatherCool commented 6 years ago

STP55NF06L

The flux was the issue not the Mosfet. These work great.

ec-cts commented 6 years ago

Thank you FatherCool.

ec-cts commented 6 years ago

One more question:

Do you use resistance between G-S of the mosfet? If so, the value of the resistance is 1.5 koh?

FatherCool commented 6 years ago

Yes you need resistance there to get the mosfet to release.

The value isn't so important. I think I used a 10k as its what I had.

ec-cts commented 6 years ago

Again thank you very much