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Resource: Transistor List

Posted: Tue Nov 09, 2004 10:04 pm
by HACHI-RYOKU
I'm puting together a transistor list to help with modding. This way you can use this list to identify transistors on a PCB as either NPN or PNP. So, if you're like me and you dual cell everything or add li-poly batts, then you can change out the fets with like fets and not have to worry about making a new H-bridge. Also when you make an H-bridge with the standard fet mod (all npn fets) then you have to reverse polarize some of the fets, witch effects it's performance. This doesn't mean your car will go slower, but it limits the amount of amps you can put through it. Replacing the regular transistors with like fets (npn for npn, and pnp for pnp) is better for things like quad cells and li-poly batts where you will be using more current. It's also a little easier to just replace the fets with like fets instead of making a new H-bridge.

If your all for this then help me make a list. Here's a start.
The transistors are identified by reading the tops of them.

NPN: D9D,KEY,FAY,6B,Y1
PNP: B9D,KIY,EA0,5B,Y2

So, if you see these in say, a ZZMT, then you don't have to figure out how to make a new H-bridge on a new PCB, you can just change the trannies out with like fets. It can operate the pnp fets because the voltage is high enough to open the gate.

These are the ones I've already identified. If anybody knows of others, then please add them to this list.

Posted: Tue Nov 09, 2004 10:21 pm
by betty.k
bloody good idea! :-)

Posted: Wed Nov 10, 2004 8:10 am
by DarkTari
betty.k wrote:bloody good idea! :-)
I second that emotion!

So what you're saying so far is that an NPN fet will replace the stock D9D,KEY,FAY,6B,Y1 transistor, if I'm saying this right ?

Posted: Wed Nov 10, 2004 9:13 am
by HACHI-RYOKU
Exactly.

The two fets that I use are;

NPN fet- IRLML2502
PNP fet- IRLML6401

I get them from Digikey online.


This is mostly commen knowledge, but I'm puting it here so everybody doesn't have to search through different places to find the fets and a place to order them from.

UPDATE:
Digikey link;
http://www.digikey.com/?trackcode=bizcom

Irlml2502 link
http://www.digikey.com/scripts/DkSearch ... wordSearch

irlml6401 link
http://www.digikey.com/scripts/DkSearch ... wordSearch

Posted: Wed Nov 10, 2004 11:31 am
by hue35
Wow, great thread dude. So, let me get this straight,
I normally use the RLML2502 and follow this diagram...
(for the old-school Bits I love so much)

Image

... am I to understand that if I get some IRLML6401's, I
can avoid the fucked-up rotated fets and jumper wire routine?
I can just do a direct swap of those two transistors (the ones
marked "POS 3" & "POS6") with the 6401's? Uhhhhh.... shit,
thanks for the info. Is this common knowledge? If it is, I've
been under a rock, this sounds like a WAY better way to go...
those little wires made me lose most of my hair... not to
mention all the shooting pains in my left arm.

Posted: Thu Nov 11, 2004 10:55 pm
by HACHI-RYOKU
Yes, but this trick only works with dual cells or better. The PNP fets need a higher voltage at the gate, so a stock single cell with PNP fets wont work.

I meant the type of fets and where to find them is commen knowledge. Most people know what kind of fets to use and where to get them. Not alot of people mention the PNP fets, so I reposted all of it for that reason, and to make it easier if anybody wants to hunt them down.

I can do most different fet mods pretty easy, but it's always a pain in the arse to try and figure out how to make a new H-bridge on a different PCB. I still do the original fet mod on the few single cell cars I have. A single cell with fets still has an outstanding performance with great control.

Plus unless you double or triple stack the NPN fets on an all NPN fet H-bridge, the current used from quad cells and li-poly bats is too much for the fets. I'l explain why. I burnt out a few fets learning this. The standard fet mod basically repolarizes the two fucked up rotated fets in your diagram. When you repolarize a fet and make the current go a different way it was meant to go, then it no longer works within it's factory predicted specs. For example, the factory specs of the irlml2502 say it can take up to something like 20 amps. But it can handle much less if it's repolarized. Double stacking the fets is also much easier when you're using like fets. You don't have to try and set up the whole stack in a funky position with the extra wire for repolarization. You simply stack them. No wire and less hassle.

Posted: Fri Nov 12, 2004 10:23 am
by hue35
I kinda figured that was wishful thinking on my part... great info, though. Thanks.

Posted: Fri Nov 19, 2004 6:23 am
by HACHI-RYOKU
An update.

Don't change the trannies in ZZMT's for like fets and expect it to work. There is more that needs to be done besides a simple tranny swap. Codesuide and PH2T did an outstanding job figuring this one out. Look it up in the "weird science" department if you want to fet mod your ZZMT.