The Sub-Genius MOSFET mod

ph2t · Post by **ph2t** » Sat Aug 23, 2003 8:12 am

bdebde wrote:ph2t,

Is there a big difference with the stacked fets, is it worth the extra hassle?

I noticed a difference, yes. The car is just "punchier" off the mark if you know what I mean. As to it being worth the extra hassle, yes!

ph2t.

maximan · Post by **maximan** » Sat Aug 23, 2003 8:35 am

tutorial tutorial please please in detail please more pics to

ph2t you

lefftoe · Post by **lefftoe** » Mon Aug 25, 2003 8:14 pm

ph2t wrote:
bdebde wrote:ph2t,

Is there a big difference with the stacked fets, is it worth the extra hassle?
I noticed a difference, yes. The car is just "punchier" off the mark if you know what I mean. As to it being worth the extra hassle, yes!

ph2t.

i've double stacked forward only, and you can tell a difference.......
i started adding lead weights (those little round ones that you clamp onto a fishing line) into the chassis........i got a good drifting booster bit now...

ph2t · Post by **ph2t** » Tue Aug 26, 2003 12:25 am

Cool, good stuff man. Gotta go get some old fish sinkers and do the old *bash* *bash* with tha hammer.

ph2t.

ph2t · Post by **ph2t** » Fri Sep 19, 2003 10:32 am

Been do some more dev on this. Credis to Matic for the info and I think original design credits go to micro_amps for this one.

With the two fets that are soldered the dodgy way. ie: one leg hanging astray, there is the problem with them not being flat on the pcb and therefore it's tricky to be able to solder well.

So we flip the buggers,..

In the two pics below the left one is original and the right has it's pins bent upwards. Be careful not to snap the pins on the fet whilst bending them the other way.

So, you then flip the fets upside down and place them on the pcb.

Here's another angle. Note I am talking about the two fets closet to the black blob.

Now we connect the fets together as per the diagram. Note that the MOSFET pin that the wire connects to must not be soldered to the pcb. This is on the flipped fets side of the wire only.

shamon

ph2t.

Matic · Post by **Matic** » Wed Sep 24, 2003 4:48 am

Actually you don`t need to bend the legs which are connected with wires. Thats two possible breaks less ...

HappyAric · Post by **HappyAric** » Fri Sep 26, 2003 11:43 pm

Ahhh! Finally got mine done. Got the mostfets from Superfly last night and started installing them this afternoon. (Thanks Superfly) Took me about 15 minutes to nail the first two and three frustrating hours on the others. At times I could get a fast reverse and no forward. Troubleshooting included half a dozen applications and removals of those two mosfets. Suprised my PCB board doesn't look like scrap after how angry I got. Did manage to peel off one tab, thank goodness it was oen of them I didn't need. Just finally glad I got this thing working, wanted to share my happiness with you guys.

That's a lxx booster btw. I got it from toyeast with a bus shell. Thing rolls around like a dog now. Appreciate all the information that anyone's ever posted. Great stuff.

SuperFly · Post by **SuperFly** » Sat Sep 27, 2003 8:34 am

Glad you got the fets and got them working. I cracked a smile when I read your install notes, as that's pretty much the story on more than one that I've done. Get all the transistors removed and most of the fets attached in 20 minutes, and then spend an hour or two trying to get the wires attached and all the troubleshooting done. It's nice when it works, eh?

SPEED · Post by **SPEED** » Sat Oct 18, 2003 10:50 pm

sorry to bring up an old post, but i'd really like to try this mod out. My props to all you who did this and thanks for puttin up all the diagrams. i do got some Q's though.
While cruzin round FRYS electronics down here in San Diego, i went lookin for mosfets. I was lucky enough to find some, but the packaging said "Surface Mount transistor" and no where did it saye MOSFET. I wasn't quite sure which one to use, they had several different ones. My first question is, which MOSFET or "surface transistor" am i supposed to get. $9 for 25 of them is pretty good, but i'd like to save my $9 until i know for sure which to get. It seems as though many, or most of you use the mosfets from digikey.com. the mosfest from there are from the company Iternational Rectifier. Are those the only mosfets that you can use for this mod (the one from IR)??? I remember seeing "AF" on top of one of the packets of transistors at FRY's, and other markings on the others. They look VERY similar to the transistors in the bit pcb (as in size shape ect.). If you can tell me what i should be looking for and what kind of "surface mount transistor" to use that would be awsome
In this diagram:

are all the stock transistors swtiched out with the new mosfets??? OR do you only replace 4 of them???

Sorry for the long post, but i just wasn;t sure with a few things. Thanks in advance for any help.

Keep Pimpin'...

bdebde · Post by **bdebde** » Sat Oct 18, 2003 11:28 pm

The irlml2502 mosfets from international rectifier are probably the lowest resistance fets you can get. If you use suface mount transistors, which are not fets, there will likely be no change (that is what is in there now), in fact it may even be a downgrade if the ones you get have higher resistance than stock.

SuperFly · Post by **SuperFly** » Sun Oct 19, 2003 3:30 am

How many do you need? I think I probably have some I could break off. $1 each, shipped in the US. You need 4, but I've ruined a few doing the mod, so I would get a spare or two. PM me if ya want some.

I've checked out Fry's inventory in Portland, and they didn't carry what you need, according to their "expert". If you search this forum, you can find all the info about which part # to order from Digikey. They do have a $5 fee for orders less than $25, and you get price breaks at I think 10 and 100.

red2cwm · Post by **red2cwm** » Mon Oct 20, 2003 10:29 pm

Is the color diagram posted by ph2t above the correct way to fet a MS Pro?

bdebde · Post by **bdebde** » Tue Oct 21, 2003 8:02 pm

red2cwm wrote:Is the color diagram posted by ph2t above the correct way to fet a MS Pro?

Yes it is.

vinnyg · Post by **vinnyg** » Thu Nov 06, 2003 5:58 pm

ok, i thought i knew how to do this mod, like in the black and white diagram. but in the color diagram the flipped mosfets are connected to different points. can someone check this out and tell me the right way to do it? thanks alot

hue35 · Post by **hue35** » Thu Nov 06, 2003 6:12 pm

vinnyg wrote:ok, i thought i knew how to do this mod, like in the black and white diagram. but in the color diagram the flipped mosfets are connected to different points. can someone check this out and tell me the right way to do it? thanks alot

The same pins are connected. The mosfets with black dots in the color diagram are flipped upside down, so it looks kinda backwards.

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