AB MOSFET - Sourcing components

[Genista]

I've successfully built my first MOSFET switch and I'd like to move on to an active braking design.

The n channel MOSFET I used for my first switch is ok, but I'd be happy with a higher current rating.

However the problem I'm having is sourcing a suitable p channel.

Locally I only have a Maplins and they don't sell anything suitable. So, before I scour RS or Ebay, can any other DIY'ers share what they're using?

Or does anyone have an Extreme Fire SW-Evolution they'd like to donate to me

[Gecko]

Re: AB MOSFET - Sourcing components

The two mosfets i use are

IRLS3034PBF
IRF4905SPBF

you can get them from http://www.digikey.com/ or http://irf.com/

[knarf3]

Re: AB MOSFET - Sourcing components

If you two are making them how much would an active braking mosfet set me back????:D

[Genista]

Re: AB MOSFET - Sourcing components

£1000....

Gecko, how do you find that form factor? is it not a surface mount? How does it handle heat dissapation?

[knarf3]

Re: AB MOSFET - Sourcing components

£1000....

Gecko, how do you find that form factor? is it not a surface mount? How does it handle heat dissapation?

There are 2 00 to many me thinks...lol :D

[Genista]

Re: AB MOSFET - Sourcing components

Worth a try...

[HuntR]

Re: AB MOSFET - Sourcing components

I have a brand new infected airsoft mosfet for sale when it arrives. It's by far the best AB mosfet around

[Genista]

Re: AB MOSFET - Sourcing components

Having dug in to the design a little further, it turns out that it's a passive braking design. Which, it seems most are. The only ones that aren't seem to be ones with some sort of processor/controller.

Have I uncovered a conspiracy? :eek:

[Genista]

Re: AB MOSFET - Sourcing components

All built and working ok so far. Field test on it's way.

[Genista]

Re: AB MOSFET - Sourcing components

[richardy]

Re: AB MOSFET - Sourcing components

ive looked my self the p channels are hard to source over here if you contact terry at extremefire he will sell you just the componnents

Basically with out resorting to a large order over here its just not like in america where you can walk into any shop and get one.

you can find the n channel easy enough though

Becuase of the shipping from the states its turned into a bit of a rip off some of these mosfets..

The active breaking on the ab mosfets works fine. The computer controll ones do more though, stuff like slowing down the breaking so its not so harsh.

[Genista]

Re: AB MOSFET - Sourcing components

Found some usable p channels on http://uk.rs-online.com/web/ (plus plenty of n channels.)

Seems there's quite a bit of scope on the spec for the p channel.

Now if only I could get my head around where the back emf is going...

[North West Outpost]

Re: AB MOSFET - Sourcing components

http://www.electronics-tutorials.ws/...or/tran_7.html

That may help...I did electronics 20 odd years ago at college but forget these days...

[Genista]

Re: AB MOSFET - Sourcing components

As the motor load is inductive, a simple "Free-wheeling" diode is connected across the load to dissipate any back emf generated by the motor when the MOSFET turns it "OFF".

It does actually. The mosfets most people use include a 'body diode' but I understood this to be to to protect against reverse voltage, rather than 'dissipate' emf. Maybe it's a nice side effect.

Cheers