Jump to content

to add your 300x250 banner, pay ad zone 5
Airsoft Atlanta is your source for quality airsoft guns and rifle parts
to add your Text Link here, pay ad zone 3

AirsoftAtlanta.com AirsoftNMore.com Airsplat.com AirsoftRC.com
Vote for us to add your 180x30 banner here, pay ad zone 2

If you appreciate this website, please ASF Donation or Check Out the ASF Store. If you can not help us financially,
then at least help us by telling a friend: Share us on your favorite social networking website Bookmark and Share
Sign in to follow this  
plloppii

Making a mosfet

Recommended Posts

Sorry for posting again.

 

So I want to make a mosfet to reinforce my kwa m16 for lipo use.

I followed a tutorial on youtube- http://www.youtube.com/watch?v=6hLeOsiJMao...;feature=relmfu

 

and I came up with a parts list on ebay-

here are the ebay item numbers.

mosfet- 260814939094

diode- 260933249232

100ohm resistor- 250816558209

2.2k ohm resistor- 110871076326

 

I don't understand the electrical properties and numbers listed on the pages so

can anyone confirm these items for me please? any tips for making one?

 

thanks.

Noah

Share this post


Link to post
Share on other sites
Sorry for posting again.

 

So I want to make a mosfet to reinforce my kwa m16 for lipo use.

I followed a tutorial on youtube- http://www.youtube.com/watch?v=6hLeOsiJMao...;feature=relmfu

 

and I came up with a parts list on ebay-

here are the ebay item numbers.

mosfet- 260814939094

diode- 260933249232

100ohm resistor- 250816558209

2.2k ohm resistor- 110871076326

 

I don't understand the electrical properties and numbers listed on the pages so

can anyone confirm these items for me please? any tips for making one?

 

thanks.

Noah

 

d58b0447fbea1c3a6925b0f63affdb85o.jpg

 

Translation:

 

Motor: Motor

Bateria: Battery

Excitación: Mosfet´s yellow wire

Gatillo: Trigger

 

It´s the diagram of my double mosfet with active brake. Hope I helped :a-famerican:

Share this post


Link to post
Share on other sites

There are several huge threads about MOSFET building in the pinned topics, I suggest you read them. And if you aren't very good at soldering, don't try to build you own.

 

And I can't recommend that you buy the IRF3205 from overseas sellers on Ebay, I did that a while back and had 20% of the 10 I bought in that way fail very quickly or not work at all. Get the IRLB3034 on Digikey, they have a great reputation, and the 3034 beats the 3205 in every way. And buy more than one.

Share this post


Link to post
Share on other sites

Don't follow the diagram that ASESINO keeps posting, there are better ways to build MOSFETs than that. Also, the 33k resistor is wrong, you want something closer to 2.2k ohms. And that guide that Baios4 linked to is great, but you don't need to use the ring terminal on the drain tab, just solder it on directly.

 

You can buy the IRLB3034 here: http://search.digikey.com/scripts/DkSearch...yWords=irlb3034

Share this post


Link to post
Share on other sites
Don't follow the diagram that ASESINO keeps posting, there are better ways to build MOSFETs than that. Also, the 33k resistor is wrong, you want something closer to 2.2k ohms. And that guide that Baios4 linked to is great, but you don't need to use the ring terminal on the drain tab, just solder it on directly.

 

You can buy the IRLB3034 here: http://search.digikey.com/scripts/DkSearch...yWords=irlb3034

 

Mmm, works fine for me :a-confused: , in fact, it´s not my creation, it´s made by a electronics technician. Oh, maybe it´s because it´s only suitable for my non upgraded P90, I mean, no LiPo, no stiffer springs like M120 or higher, etc. Infact it´s meant to be used with 8.4v NimH battery with a m85 spring... If you´re using LiPo a hitorque and a bigger spring than a M140 , yes, I agree, don´t follow this diagram. :a-laugh:

Share this post


Link to post
Share on other sites
Don't follow the diagram that ASESINO keeps posting, there are better ways to build MOSFETs than that

 

Wow... I forgot to ask what´s the problem with my MOSFET. I hope it won´t blow after ten shots or so :a-confused: Tell me If I must change it :a-laugh:

 

Share this post


Link to post
Share on other sites

I'm not saying that it won't work, but that there are better ways of doing it. I mainly don't like the layout, its bulky and inefficient.

 

However, I'm happy to see that not everyone has jumped on the "OMGYOUCAN'TMAKEYOUROWNABMOSFET" train though. Some people have this idea that they are more likely to fail (and they are, two transistors instead of one, twice the probability of failure lol). If you don't use a fuse, then yes an AB MOSFET could be more dangerous though.

Edited by MotorMouth93

Share this post


Link to post
Share on other sites
im following the building schematic from unconventional airsoft.

 

can anyone give me a link to a big diode?

 

One of the pictures has every Digikey reference number for all of the main components. I can't remember off the top of my head but I know it's the standard black and white one with all of the individual parts shown. Just look for it, you'll find it.

Share this post


Link to post
Share on other sites
Is this diagram Ok? :a-confused:

 

mosfetror.jpg

no it's wrong ( reason 1-2 ).

1. Cathode of the diode ( the white line of the diode ) should connect with the middle terminal ( D or Drain ) of mosfet.

the metal side of the mosfet, is the same with Drain. You cut the middle terminal in order to be more comfortable to connect the wires.

 

2. Diode type is, 5KP18A .

 

also check out this one.

 

I'm not saying that it won't work, but that there are better ways of doing it. I mainly don't like the layout, its bulky and inefficient.

 

However, I'm happy to see that not everyone has jumped on the "OMGYOUCAN'TMAKEYOUROWNABMOSFET" train though. Some people have this idea that they are more likely to fail (and they are, two transistors instead of one, twice the probability of failure lol). If you don't use a fuse, then yes an AB MOSFET could be more dangerous though.

 

as MotorMouth says,

it's good idea to always install a fuse. once, short circuit appeared at my motor connectors and the 30A fuse blow up!

when I opened the protective cover of fuse, there were only small pieces of glass.

Edited by Baios4

Share this post


Link to post
Share on other sites
no it's wrong ( reason 1-2 ).

1. Cathode of the diode ( the white line of the diode ) should connect with the middle terminal ( D or Drain ) of mosfet.

the metal side of the mosfet, is the same with Drain. You cut the middle terminal in order to be more comfortable to connect the wires.

You're right that the TVS is backwards, but the ring-tongue on the drain tab is the proper way to implement the 3034, since the internal connection of the drain pin is very thin and fragile. You should not solder directly to the tab either, because the 3034 is prone to failure upon any internal reflow which would occur if you tried to solder to the drain tab.

 

So besides the TVS being the wrong way around, it's an excellent diagram.

 

Another tip that I can offer since I wrote the guide is that you can use thermal adhesive to bond a bit of aluminum or copper to the back of the 3034 and it can be a very effective heatsink for high-demand setups.

 

Also, never try and make your own AB 'FET unless you're following Terry's SW-Computer designs - the simple AB circuit is dangerous.

Share this post


Link to post
Share on other sites
So besides the TVS being the wrong way around, it's an excellent diagram.

 

I have copied my diagram from the picture that Baios4 said but with some perspective to see how all elements would be mounded. So... the white line must be facing the wire towards the screw, right?. I must confess that I know nothig about electronics but what´s + and - in the battery :a-blushing: Aniway, I have corrected the mistakes (I hope), Is it Ok now?

 

mosfetaza.jpg

Edited by ASESINO

Share this post


Link to post
Share on other sites

Can some one explain in simple terms why the diode has to face that way?

 

and buppus, what do you mean by

"but the ring-tongue on the drain tab is the proper way to implement the 3034, since the internal connection of the drain pin is very thin and fragile. You should not solder directly to the tab either, because the 3034 is prone to failure upon any internal reflow which would occur if you tried to solder to the drain tab."?

 

Share this post


Link to post
Share on other sites

In short, if you solder on the drain tab, there is a risk you may fry the internals of the mosfet. The diode is kinda like a valve, it protects the mosfet from voltage spikes that can occur. I'm not 100% sure how this works, but it probably has to do with the arcing that occurs in the motor.

Edited by Lefse

Share this post


Link to post
Share on other sites
You should not solder directly to the tab either, because the 3034 is prone to failure upon any internal reflow which would occur if you tried to solder to the drain tab.

 

Oh really? How come the 4 or 5 that I've directly soldered are all working fine? I've soldered them back to back before, with solder flowing completely between the two drain tabs, with zero problems. Is it more likely to cause problems than the regular bolt? Possibly, but are they as ridiculously fragile as you suggest? No.

 

Also, never try and make your own AB 'FET unless you're following Terry's SW-Computer designs - the simple AB circuit is dangerous.

 

Also, as an electrical engineering undergrad, I know what MOSFETs are and what they do. The simple AB circuit is only more likely to damage a gun than the standard design if you don't use a fuse. And of course its more likely to fail, you have two transistors instead of one, so double the odds of failure. That said, I've been using one for a few months, and it's worked great.

Edited by MotorMouth93

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...