Announcing: Spider – External FET board

[Aaron]

ausmicro.com Launches their own version of an external FET mod.

[/quote]I think everyone knows by now the best way to get performance from a Mini-Z/iWaver or XMod board is to play with the FETs. I’ve long been a supporter of Internal FET stacking for most ‘light duty’ use but in recent times have become aware of issues concerning FET stacks on newer Kysho and iWaver boards. It appears that newer boards often cannot control more than 4 FETs per stack, and the drive voltages to these FETs are more variable than on earlier (Typically MR01) boards.

ausmicro.com still belives an internal FET mod up to 3×2 is an excellent solution to 80% of performance desires, but what happens when you want or need more?

The answer is ‘Spider’

[/quote]‘Spider’ is our name for our first generation External FET mod. Measuring just 20mm x 25mm Spider can lurk on your chassis giving you the smooth as stock throttle response with the ability to handle any hot motors. Spider uses high quality FETs from International Rectifier and is available in a number of configuratiosn to suit your racing needs.

How many Spiders are there?

[/quote]ausmicro.com is planning on selling Spider in 5 different forms. You will be able to select a Spider configuration to suit YOU. You can have your Spider with leads (legs?) pre-attached or you can supply your own!

How does Spider Perform?[/quote]

Spider performs well, typically a Spider has an internal resistance of about 10-15mOhms. That’s the same resistance range you’ll get from a 5×2 or 6×2 stack of IRF7317 (or SI4562DY) FETs without the risk of poor throttle control and surging! If you’re still running IRF7389 FETs you’d need a 9 stack or MORE to get the same performance!

What does Spider Look like?

Spiders full implementation gives you approximately 200mm of leads, consisting of rainbow cable for the control signals, and silicon jacketed PN Racing cables for the battery connections and a PCb mounted screw terminal for your motor connections. (pic Attached Pic)

How is Spider Built?[/quote]

Spider is built on a commercially prepared 1.6mm thick PCB. The board is fully tinned and will not suffer degradation. The PCB mounted IRF FETs can be bonded to a heatsink on EITHER side of the PCB as the PCB acts as a direct contact heatsink as well!

All FETs are 1st quality commercial sourced units, NOT Hobbyist grade or ‘Samples’. All this means you’re getting a unit built to last. Selecting a ‘Bare-Board’ Spider lets you choose your wiring and heatsink options!

Watch this space for more Pictures of the Spider family!

[/quote][/quote][/quote]

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Site Owner Guy.

[Aaron]

Closeup of the ‘Business End’

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Site Owner Guy.

[peteWah]

It looks the part mate…

Good Job.

[betty.k]

looks like australia got the monopoly on 8 legged critters with BITE!!!!(yeah yeah, add the motor wires!)

so, am i correct in assuming that the spider requires the removal of the stock fets and the rainbow leads got to the gate signals? like the, you know?

[Aaron]

Yes Betty. Credit where it’s due! Like the the WoahNelly (http://www.woahnelly.com) turbos the rainbow wires are for the gate signals. At the end of the day this is the best, most idiot-proof and cost effective for production way of handling the Gate signals.

Likewise the removal of stock FETs. Units running off the motor terminals simply do not have the fine throttle response and outright performance that a FET substition type mod has.

I’ve murmered about buliding a small S-08 package based unit for a while and this is the first ‘production’ version. Having gone through the process of doing the board designs and getting them made commercially has proven interesting and I can already see where improvements can happen.

My key goal with Spider was to match the width of the Mini-Z PCB and allow for different cooling, cabling and mounting options, this also lets us be very flexible on pricing as you can buy a board with FETs supplying your own wires for a lower price.

A.

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Site Owner Guy.

[Aaron]

‘Spider’ Install Instructions!

Download the attached PDF document to see how the Spider installs!

Instructions available at http://shop.ausmicro.net/download/SpiderInstall_v2.pdf

Edited by – Aaron on 30 September 2005 10:41:27

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Site Owner Guy.

[bithed]

..The Spider looks good…Nice bit of work and a very professional presentation so far…PanicToys is very interested…

[z-beam]

will you be offering an instalation service as well like the old fet stacking service Aaron?

[Aaron]

Revised Instructions

[/quote]http://shop.ausmicro.net/download/Spider_Install_v2.pdf

Installation

[/quote]Yes we will install Spider for a modest fee, you mail us the chassis (or buy a new Chassis) and we will install the spider and ship to you.

[/quote][/quote]

Edited by – Aaron on 30 September 2005 10:42:35

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Site Owner Guy.

[Admin]

is this availabe now? if not, when?

[pimpsmurf]

I already ordered mine. Should be here next week! 🙂

-JNY

[Aaron]

Yep, they’re available now. I have a few backed up orders while we wait for the next batch of FETs to arrive (due Monday/Tuesday) and then we’re back in full-production.

A.

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Site Owner Guy.

[Admin]

i just checked these things out and they sound incredible. i am a newbie to the hobby and was wondering if this is what i would need if i wanted to run a car with a li-on setup wih 4 batteries and a seriously hot motor? i was als wondering if 4 batteries is over kill?

[betty.k]

not sure about the limitations of the spider but 4 lithium cells is way overkill! but then again i think 2 lith cells is overkill. unless you don’t need to turn, ever!

[Admin]

always good to get someone’s point of view. thanks for bringing me back to reality.

[Aaron]

The ‘Spider’ can handle up to 20v so that’s not a problem BUT your stock Mini-Z board is deigned to run at a MAX of 6v (4x AAA 1.5v Cells) and typically runs at 4.8v Pumping in 7.2v will likely cause problems with other components.

You are best off running a small regulated supply of 5v for the board if you go LiPo. ph2t is working on (around baby production) on a version of the Whoa Nelly that offers a regulated supply etc to run with LiPo installations safely.

Also if you’re considering going for more voltage than 7.2v (14.4?) you’ll probably want to investigate using motors built for 12v not the ‘stock’ style voltage ranges. PN make a pair of 12v 130 class motors that could be very interesting.

A.

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Site Owner Guy.

[Admin]

i really appreciateall of the great input.

[peteWah]

I might just have to buy the Blue Alfa 0.15 and send the spyder back to you….
Or Buy the 02 Woodone Supra you have in the shop,
I just dont Know anymore.

Just thinking the particular car i was having the problem with has past its life time…
TWas a Jap car too, Ohh It had a good life…

RIP Jap Electronics, I may still use the chassis

[pimpsmurf]

I got my spider in today. You should include turbo_v1.jpg or some other info on where the wires go to from your PCB for us cheapos who bought the bare board! =)

There was probably a better way of saying that, but I’m off to install it!

-JNY

[Aaron]

Yeah sorry about that – I’ve added the BareBoard diagrams to the Shop page, and also will be including the printout with the barebaords.

A.

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Site Owner Guy.

[Aaron]

Keeping your Spider Happy

With a few units now out in the wild it seems just like every Turbo that’s gone before it there’s a need to remind people that while these things will may even a stock car faster you shoudl be careful when upping voltages or motors.

The Spider is designed to be small, and it can switch some pretty high current but this means nothing if you let it overheat. If you’re planning long repeated run-times or having LiPo power or even just runnign a HOT motor then I suggest attaching a small alloy heatsink over the chips. This will ensure continued performance and reduce risk of failure.

In short, don’t cook your Spider!

A.

[/quote]

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Site Owner Guy.

[pimpsmurf]

I have a tiny alloy heatsink from radioshack that fits on the back of the board perfectly. Should I get some silicon and try to use arctic silver adhesive to mount directly to the chips? Or perhaps I should try to shoot some arctic silver thermal compound between the chips and the board, and mount the heatsink to the back of the board.

What I’m really trying to ask is, is the board a good enough conductor for my plasmatomic/uberdash with lithium power, or should I mount directly to the chips?

Thanks again,

-JNY

[Aaron]

Mount direct to the chips for the best results. I’ve tested with a heatsink tot he board and it does work, but the chips do run hotter.

I’m hoping to do some more playing this weekend with a demo car 🙂

A.

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Site Owner Guy.

[bithed]

Delicious Hmmmmmm 😀 Demo car…

[pimpsmurf]

I guess I was trying to go the easy way. Time to find some silicon! =)

*EDIT*

Here comes a question I’ll regret. I apologize ahead of time.

I was going to use a radioshack 7805 +5v regulator with appropriate caps and aheatsink to attempt to run 5v to my MZM PCB and hook up the batteries directly to the spider. I drew a crude diagram in MS paint (don’t have any of my software on this machine yet.) The motor is left out of the picture.

What I wonder is, will the spider board still function the same as it would without? I mean, I don’t know if it would make the spider unable to go into enhancement mode because the FETs are seeing different voltages across the gate and source. I admit that all I know about FETs I learned from a 20 page chapter in a book and forums, so try to go easy on me =)

I’m not even sure if it will work at all. The idea is to be able to run lipos and regulate the voltage to the mainboard to 5vdc so that I loose the servo jitter and promote the lifetime of the board. Of coarse, performance in the main goal, so anything hindering it won’t happen.

-JNY

Edited by – pimpsmurf on 12 August 2005 10:01:37

[Aaron]

It will work fine. What’s been learnt is that the Gate voltages fromt he PCB don’t inclrease with the increased PCB voltage. The FET s we use are bassically ‘logic triggered’ types which means they’re ‘On’ or ‘OFF’ and the only variance is internal resistance.

Ofcourse the higher the gate voltage you feed in the lower the resistance.

A.

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Site Owner Guy.

[pimpsmurf]

I thought they were enhancement mode FETs, whichI thoughtwould fully bypass the gate at a certain voltage. Your the expert though. if you say that it will decrease performance , maybe I can put a resistor inline with the servosomehow to cut down on the jitter. I need all the juice I can get. alloy is heavy! =)

*shrug*

-JNY

Edited by – pimpsmurf on 13 August 2005 06:30:02

[Aaron]

Yikes!

Don’t feed teh PCB more than 5v!!!

The Gate outputs of the Kyosho Electronics will always be only around 3v and 5v no matter what voltage you feed in. That’s why FET drivers (like MAZ627) work well..

A.

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Site Owner Guy.

[pimpsmurf]

AHH HA! I thought that was ‘The Way It Works'(tm)! So I can use that and get the same results as I would without the 5v regulator (meaning, it won’taffect the internal resistance of the FET at full throttle )

So with the setup I drew above, I will still have 7.4VDC hitting the motor, and be full throttle capable (ie. the lowest resistance in the FET turbo possible. Your the best!

Thanks for the great info!

-JNY

[ph2t]

Quote:

Aaron wrote:

Yikes!

Don”t feed teh PCB more than 5v!!!

The Gate outputs of the Kyosho Electronics will always be only around 3v and 5v no matter what voltage you feed in. That”s why FET drivers (like MAZ627) work well..

A.

Yeah, if you isolate the spider from the MZM pcb and attempt to drive it that way, the pchan mosfets will always be in an ‘on’ state. this is due to the fact that Vout from the PCB is 5v BUT Vcc into the mosfets is 7.2v (or grater). This means that the voltage drop across the Source-Gate junction on the pchan mosfets is 2.2V, enough to keep them on. Ergo: as soon as you apply throttle and turn on an nchan mosfets, you will create a short and blow the buggers.

This is described in incredibly anal detail in my nelly thread, somewhere………

ph2t.

[Aaron]

About page 12 or 13 I think 🙂

Overall the ‘issue’ is as much a limitation of the Kyosho Electronics as it is an issue with overall MOSFET designs when used this way. Using a Quad (or 2x dual or 4×1) MOSFET drivers will meant hatt he FETs get driven witht he same voltage as the ‘Source’ (ie battery). This mankes them markedly more efficient and also means you can regulate the voltage to the board.

Overall it would be nice if the stock boards used MOSFET drivers, accepted any battery voltage, and so on. sadly not the case, although someone once suggested it may be possible with an iWaver board to achieve the affect of MOSFET drivers by cutting the power traces at a certain point and applying the higher battery voltage there.

A.

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Site Owner Guy.

[Aaron]

Update:

‘Spider’ boards produced from this week are lighter than their predecessors! The electronics stays the same but we are now building them on 0.8mm boards. The new thin board versions save a minute amount of weight and sink heak a little better.

Under Development

EnsyWeensy is coming and will be the smallest footprint external FET solution available. How soon? Well we’re still testing to make sure we’ve got a solution that will knock your socks off!

A.

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Site Owner Guy.

[Aaron]

Revised Instructions:

Includes:

• XMODS Install
• Bare Board Wiring
• Minor changes in layout and explanation

Download from http://shop.ausmicro.net/download/SpiderInstall_v2.pdf (Also Attached)

A.

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Site Owner Guy.

[Aaron]

Newest version of the Spider (still in development) can be internally mounted in a MR01 chassis!

A.

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Site Owner Guy.

[Aaron]

Following a succesful development phase of over 6 months Spider Mk2 is about to hit the shelves.

Due in 14 days this Spider packs the same big bite into a much smaller package!

A.

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Site Owner Guy.

[Author]

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