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dave, I'm currently pulling an all nighter here to try this out for myself. yes, my monster came today. I gave it about an hours run before I couldn't help myslef and started pulling it apart.


I'm working on a setup similar to the 1st gen bcg boards, where you flip one set of trannies, hopefully it won't involve the level of setup code has done but ya never know....

also, don't know if anyone has noticed but the onboard DCDC convertor converts to 5V!!!!! yes AND the output from the RX IC is > 4V, this is a good thing for switching mosfets, a very good thing indeed......

and so it continues.......

ph2t.

Cool ph2t, I'll go ahead and try it code's ways since I have just enough n-channel and p-channel FETs left after yesterdays escapade.

also, don't know if anyone has noticed but the onboard DCDC convertor converts to 5V!!!!! yes AND the output from the RX IC is > 4V, this is a good thing for switching mosfets, a very good thing indeed......

I read that in one of code's post, I think on MRCC. That is cool. These things are really torquey as is, FETs should really get it kicking some.

Did you get the motor set, ph2t?

ph2t wrote: Damn there's a lot of work involved!

Well, as I noted somewhere in there, its not really that complicated, its just that I like to reuse PCB traces as much as I can instead of installing long jumper wires. All you really need to do is remove the six transistors and four resistors, then somehow connect up the gates of the four new FETs to the pads left by the resistors R21 and R9(note, its not the R9 labeled on the board, 'R9' is the wrong name, but I can't read the right name on my board, somebody please be sure to get me the right name. Its probably printed underneath that resistor).

To connect up gates I've bridged the resistors to move the signal through, then used the old Q11 and Q12 pads to get the right signals to the right FETs.

ph2t wrote:What is the performance increase like? Is the margin of increase as great (relatively speaking of course) as the original bit's and nonSE zipzaps?

well done again mate!

I'm embarrased to admit that I didn't profile the speed before I started, do I can't say how much of a speed improvement this is. Subjectively, not that much. However, there does seem to be a fairly decent torque increase. With 21k motor, green gears and fresh batteries, If I hold it by the rear wheels and let it dangle, then put it in forward, it will always get up to 90 degrees, and sometimes can nearly start doing flips.

On wood floor its more fun than six underage Thai whores on crack (well, a close second anyway), if you turn the wheels it'll do donuts like a Zip with a big motor, but with the front wheel drive you can turn the wheels the other way, recover and drive off without ever letting off the throttle. Its like driving on ice, closest thing to drifting at 1/64th scale that I've seen. With propo steering it would be even better.

Before I did the FET mod it wouldn't slide around like this, its pretty cool.

codesuidae wrote: Its like driving on ice, closest thing to drifting at 1/64th scale that I've seen. With propo steering it would be even better.

Gahhh, why did you have to day the "D" word. Hopefully this reply will stop all the little boys from flooding this thead w/ retard replies and requests for this to be done when the collect enough allowance.

shutup man, don't jinx us, lol....

I'm testing a different method at the moment. Using just the IRLML2502 mosfets. It's similar to the original "flipped fet" method used on the BCG boards. I also remove 2 of the D9D trannies and jumper from their Base pins straight to the Gate pins on the 2502's....

There's no need to remove the resistors in this setup 'cause you're feeding a high impedance load anyways, what I mean is that there's barely any current requied to turn the mosfet on , so a current limiting series resistor in the same path would have little effect.

Ultimately, real world results with speak the truth in the end. I could also be absolutely full of it!

without code's original schematic work, none of this would be as easily achievable, my hat goes off to you dude...

cheers,

ph2t.

all i need know isa skylinez!1111 they r da r0x0rs111211~~! it b the ultimate mt of pwnage!11112112!

No seriously, why hasn't someone thrown the skyline body on there as a joke. I figured that would be the first thing I'd see.

Later,
Chrome...

oh yeah dave, I got the motor set as well man. Got it running the high speed motor with the stock gearset. Goes over fucken grass!!! I can't believe it!

Here's what I'm doing currenty. It's by no means finished, I only got done testing one direction last night before my eyes won the battle for sleep...

Looking at the top of the pcb, I removed the following. The red are the D9D driver trannies, the yellow are the S1A trannies. All four are removed.



On the underside I also removed the S2A pnp trannies...



Here's what i then do to the top portion of the PCB.

1) Remove all 4 marked trannies.
2) Solder two irlml2502 mosfets in place of the original S1A's, pin for pin mapping.
3) Run a wire from the Base pad to the Gate pad for each direction.
4) Run a wire from the Gate pad of each new mosfet to the bottom side of the PCB. They will be jumpered to the "flipped" mosfets on the other side. Still working on the pics for that.



ph2t.

it bloody works!!!!

I soldered the two fly leads to the flipped nchan's on the other side of the pcb, bridged the blue wires, she runs! yeah!

I get 4.82V for the fwd mosfet drive, that's great! Rev is less though, 4.66V. Might explain why (when stock) rev is a little less punchy than fwd. This excellent fact of a high voltage drive (>4V) means a lot when it comes to turning on mosfets, trying hard not to bar up over this, lol.....





ph2t.

Cool ph2t, but now you've left me with a dilema, I don't know which mod to try.

I did pick me up another monster today, maybe I'll try codesuidae's now, while I have the P-channels, then try yours in a few days, when I get more N-channels, on the second monster, that way I can compare.

Yep that's probably the best thing to do, but your way does look much simpler.

Descisions, descisions.

if you could afford the time to dave, doing each mosfet mod and comparing would be great!

with code's mod, I'd be interested so see what switching voltage appears on the nchan and pchan mosfets in that setup. also, the pchans have a higher resistance than the nchans, but again, this is all theory......

I'm off now to put a 3.7V 80mAh lipo pack in mine!



ph2t.

You RAT BASTARDS !!!

What with all this talk of channels and gates. It's like hearing Japanese (for me) goddamit. I can pickup and understand words and phrases, but it's all still mostly hazy and gibberish.

All this yappin makes me want to go back to the 740page 'Basic Electricty' book and my 5zillion electricity projects kit...You bitches are KILLING me here, I work 15+ hour days, I can't pick this shit back up dammit!

Aaaagony, oh AAAAAGGGGOOOONNNY.

ph2t wrote:shutup man, don't jinx us, lol....
There's no need to remove the resistors in this setup 'cause you're feeding a high impedance load anyways, what I mean is that there's barely any current requied to turn the mosfet on , so a current limiting series resistor in the same path would have little effect.

Agreed, my decision to bridge them was more of a marketing ploy for the benefit of the kiddies (resistors resist, so they must make it slower, right?) than much of a contributor to the performance improvement.

I'll check the voltage on mine tonight.

I also took some video of the MT with the mosfet mod in, I can post links if anyone wants to see.

sure dude feel free to post any and all info.

ps. I'm just a lamer trying to up my post count by posting in this thread..

codesuidae wrote:

ph2t wrote:shutup man, don't jinx us, lol....
There's no need to remove the resistors in this setup 'cause you're feeding a high impedance load anyways, what I mean is that there's barely any current requied to turn the mosfet on , so a current limiting series resistor in the same path would have little effect.

Agreed, my decision to bridge them was more of a marketing ploy for the benefit of the kiddies (resistors resist, so they must make it slower, right?) than much of a contributor to the performance improvement.

I'll check the voltage on mine tonight.

I also took some video of the MT with the mosfet mod in, I can post links if anyone wants to see.

what I like is the fact that each of the jumpered outputs are running a high voltage EVEN though there is two Gate pin sinks been drivin off it. ie, the setup I use runs the two conducting mosfets in parallel, see below.



I drew this h-bridge up over a year ago, originaly used for bits, lol....

ph2t.

more madness......

Have any of you guys noticed you get that high pitched buzzing sound and then the top speed goes to shit?

I had to graphite the transfer gear and pinion. I also had to grease up the bushings around the rear axle, the front end is still too tricky for me to tackle yet....

now shes running smooth, so I thought fuck it and installed the lipoly.




with the high speed motor and gear set, it will flip on the spot, lol.... it's soo like a 1:64 version of my madforce it's not funny.....

ph2t.