upgraded FETs - Page 4

#46 11-24-2003, 01:13 AM

amazing work neuro... simply amazing...

if you ever find yourself interested in adding lights again.. and want to prevent shorts... you may want to consider shrinkwrap around your turbo board...

anyway... by how much does your run time decrease with this much draw? just curious, because i'd like to know how many sets of rechargables i should have on standby should i attempt this and attend a competition... `=]

neurokinetik · #47 11-24-2003, 09:41 AM

Quote:

Originally posted by Pinoy274
amazing work neuro... simply amazing...

if you ever find yourself interested in adding lights again.. and want to prevent shorts... you may want to consider shrinkwrap around your turbo board...

anyway... by how much does your run time decrease with this much draw? just curious, because i'd like to know how many sets of rechargables i should have on standby should i attempt this and attend a competition... `=]

I'm still trying to figure out how to heatshrink the board while keeping the heatsink tabs on the transistors open. As for run time, I ran it for about 15 minutes this weekend with no issues (transistors never even got warm), then the following night for a couple of minutes, after which the entire car went dead. I haven't had a chance yet to tear it down and find out what went wrong. I did get a chance to line up against other XMods, and found that I was still significantly faster than others who were running stage 2 (drag or drift) motors (I am running a stage 2 drag with timing advanced). Runtime won't decrease with this mod, as it is just an "enabler". It doesn't really provide much of a performance increase, it simply allows you to run a hotter motor without worry.

#48 11-24-2003, 10:31 AM

ok cool...

in that case, may i ask, what is it exactly that you're soldering the CAT5 wire to upon connecting the boards?

neurokinetik · #49 11-24-2003, 03:50 PM

Quote:

Originally posted by Pinoy274
ok cool...

in that case, may i ask, what is it exactly that you're soldering the CAT5 wire to upon connecting the boards?

I solder directly to the pads where the old FETs used to be located. If possible, I look for the largest open area to solder to, scrape the coating off the trace, and attach the wire there.

EMX · #50 11-24-2003, 04:55 PM

I have seen neurokinetik's set up and all i can say is "wow"

its faster then mine, and im running a stage 2 drag and so was he, we both had stock bearings.

#51 11-24-2003, 05:20 PM

Neurokinetick advised to scrape the traces the fets are attached to, but i have found it much easier to use 30 gauge wire and prep the wire right. strip the wire, add a little bit of solder to the wire, and while it is still hot, stick the wire to the leg of the fet where the gate is located, it should stick just fine. Neurokinectick's way works just as well, but i thought i might post this advice if you ever feel the need to return your car to normal without a trace

neurokinetik · #52 11-24-2003, 07:24 PM

Quote:

Originally posted by bob256
Neurokinetick advised to scrape the traces the fets are attached to, but i have found it much easier to use 30 gauge wire and prep the wire right. strip the wire, add a little bit of solder to the wire, and while it is still hot, stick the wire to the leg of the fet where the gate is located, it should stick just fine. Neurokinectick's way works just as well, but i thought i might post this advice if you ever feel the need to return your car to normal without a trace

I always tin both the wire and the spot I am soldering to. Makes for a quick, strong connection.

TypeZer0 · #53 11-24-2003, 08:40 PM

i'm wondering, are you gonan show a schematic showing where to connect each pin to what pad on the circuit board?

neurokinetik · #54 11-24-2003, 10:41 PM

Quote:

Originally posted by TypeZer0
i'm wondering, are you gonan show a schematic showing where to connect each pin to what pad on the circuit board?

Yeah, as soon as I can draw one up. It's really quite easy.

Mr BigShot · #55 11-26-2003, 05:35 PM

Hows it going with the upgrading Everyone . I've seen a few 4 or 5 stack Fet upgrades for sale on E Bay for sale . Hey Neurokinetik were have you disappeared too ?

How's your project doing ? I went out and bought a low voltage soldering gun from RS ,15 volts, it looks like a big pen .Going to try upgrading my wire's first . I kinda new at this

Hey what FET's are the best to use on an Xmod ??????

neurokinetik · #56 11-27-2003, 12:51 AM

Here's an illustration of what I have done:

On the main board, IC6 is the chip responsible for driving the positive (red) motor wire. IC5 handles the negative (black) side. The graphic shows the chips how they appear on the board if you are looking directly at them, with the front of the car facing you. If you look closelty at the board, you will notice that one whole side of each chip is connected directly to the motor wires. This is the Drain pin of the MOSFETs, and as you can see, the drains of both the N Channel and P Channel MOSFETs are tied together within each chip. The diagram to the left of the picture shows the pinout of each MOSFET. It is the same for both the P Channel and N Channel. Both the center pin and the tab are connected to the drain within each MOSFET. Keep this in mind so that you don't inadvertently create shorts! Pin 1 of each chip is grounded, so as long as you tie the sources of both N Channel MOSFETs together, you only need to run one wire from the MOSFET board to the main board. The rest of the wiring is pretty straightforward. Just wire up two pairs of transistors, an N Channel and P Channel in each pair, solder the drains together, and connect the motor leads to them.

I can probably draw a complete schematic, but this should give a pretty good idea of how to do it. Basically, pretend the outlines of the ICs aren't there, and solder the corresponding pins of the MOSFETs to the proper place on the main board.

D1drifter · #57 11-28-2003, 02:19 AM

hi neurokinetik, Im new to the tiny rc forums but certainly not new to RC. I am in aww in what you have done with the custom FETs mods. Im very interested in doing this Mod to my xmod myself although with the current schematic diagram you have post, I really can't get the whole picture. If you can post the complete schematic diagram, that would be a great plus. thanks neurokinetik

Mr BigShot · #58 11-28-2003, 10:34 AM

It is quite hard to understand ! I have all the soldering stuff , and soon i will be ordering SI4562DY's <---- are these the ones to use ? for a stack of like 4 or 5 high? Well Thanks for all your hard work with the FET's wish I had the smarts to understand that diagram

TypeZer0 · #59 11-30-2003, 04:02 PM

i was curious when you did phase 1 with the IRF7389 FETS. did you happen to test out that configuration? i'm thinking of using these because they're drop in replacements but not stack them since i'm not gonna go hardcore with like 10 turn motors that make full use of that turbo board you made.

neurokinetik · #60 11-30-2003, 04:28 PM

Quote:

Originally posted by TypeZer0
i was curious when you did phase 1 with the IRF7389 FETS. did you happen to test out that configuration? i'm thinking of using these because they're drop in replacements but not stack them since i'm not gonna go hardcore with like 10 turn motors that make full use of that turbo board you made.

I tested it on the bench, but not in the car. It worked transparently compared to the stock FETs. Remember that we still don't know the specs on the stock FETs, they may actually be as good as IRF7389s. If that were the case, then you'd gain nothing by only swapping a single pair in.