Blobs, Sticks and Steps….

I figured it’s time for an update on the StepFET project that’s been on the boards for a while now.

What is StepFET? (Steppy)[/quote]

StepFET is less about being a product and more about a new method of Fet modding a Mini-Z or iWaver. Unlike a Nelly turbo a StepFET install is all internal and can be mounted in place of stock FETs on the Rx board. StepFET offers some interesting benefits over conventional stacking.

[*]Fits in all chassis without mods to chassis (unlike 3×2 or bigger in iWaver)
[*]Similar resistance to a 5×2 stack of IRF7317 (down to below 10mOhm)

[*]more ‘stock like’ throttle response and sensitivity.

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The down side is building a StepFET stack is a complete bugger of a job to do right. It takes very very fine gear and steady hands.

How do I make a StepFET?

[*]You make a StepFET by taking 4 SO-8 packaged HEXFETs, two are N-Channel and two anr P-channel. IRF7210 and IRF7809AV are a pretty good pair and were my original test items.
[*]Next you take the FETs are remove pins 1 & 2 from them all. On the P-Channel remove the legs 7 & 8 as well

[*]Now solder your N-Channel FETs down in the stock locations. Obviously you can’t solder to the pads for pins 1 & 2.

[*]Here comes your Step! Prepare the P-Channel FET legs. For the Drain legs do it like you were going to stack them. That is bend them straighter and down. For the source and Gate legs (1 & 2 ) just leave them.
[*]Mount the P-Channel FET so that it has legs for the Source and Gate line up with the empty pads on the board and solder the Drain legs onto the drain legs of the N-Channel it will be paired with.

[*]Finally use a some wire (leg of resistor is great for this) to join the Source and Gate pins to the board. I do this by soldering the wire in place to the pad and then to the pin before snipping it to length.

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You’ll see the P-Channel moutning makes a step. Assuming everything goes right the Step is no wider than the board. This can vary and there is a way to make the StepFET in reverse (N-Channel on top) if it fits better. It means your offset is done on the board though as you still need to match the stock Dual Channel FET pinout.

What’s Sticky? What’s Blobby?[/quote]

Sticky and Bobby are two new projects derived from the StepFET project. They both take the StEpFET components external. The names ‘Sticky’ and ‘Blobby’ come about due to their shape.

[*]’Sticky’[/quote] is a little 20mm long 5-6mm roundish ‘stick’ with wires coming out of the ends. Depending on the FETs used in Sticky you can see down to sub 10mOhm (better than a 6×2 stack of IRF7317) at a full 16A.

[*]’Blobby’[/quote] is another in-bred cousin of Steppy and Sticky. Blobby is more like Cube of Power[/quote] and combines the same electronic characteristics as Sticky and Steppy but brings in a better sustained power handling ability with the addition of a heatsink. Blobby is currently being re-designed to a 5 chip design that will offer 8mOhm performance in a 10mm x10mmx10mm package.
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Q & A!!![/quote]

1. Are Steppy, Sticky and Blobby better than a WoahNelly?[/quote]

   In a word no. Steppy Sticky and Blobby are physically smaller than a Nelly turbo and due to their compact size are more likely to be affected by heat induced failure. This magic trio is designed for light weight, small size and great performance with Hot but not extreme motors. The Nelly range is undoubtedly king of outright performance however this trio is designed for stealth installations and use with 4 or 5 cell NiMh.[/quote]

2. How much?[/quote]

   The FETs used in the three vary in cost from USD6 to USD10 for a set. I haven’t explored commercial pricing yet. [/quote]

3. So What FETs are your using?[/quote]

   See above, we mention the IRF FETs but really any SO-8 pack with the right specs will work. [/quote]

4. Can I buy these ready made yet?[/quote]

   Not yet. It’s likely that Steppy will be a DIY package of pre-trimmed FETs bonded together ready to solder. While Sticky and Blobby need more testing before going public. They’re a bit shy![/quote]

5. Should I buy a Nelly now or wait?[/quote]

   Buy the Nelly! ph2t makes a great Turbo and as mentioned above these are not substitues for Nelly. http://www.woahnelly.com[/quote]