Buying more shields?

[DoktorJ]

Is there any way to buy more shields, short of preordering more Digisparks?  I somehow managed to not order a MOSFET shield, and could really, really use one... there aren't any electronics supply places nearby where I could procure the necessary MOSFET, diode, etc, and my favorite online shops have $10+ minimum order amounts.

Failing that, is there a schematic of the MOSFET shield somewhere?  I know it should be pretty simple, but if I'm going to DIY, I'd like to DIY as close to the "original" as possible, so when I use the sample sketches to play around with it, I don't have to modify too much stuff

You know, Radio Shack is getting into the "DIY electronics" thing lately, and I've seen them advertise Arduino stuff... maybe you should try to market the Digispark and its shields to them?  

[DoktorJ]

Would this schematic be a safe way to \"design my own\" MOSFET shield?



FYI, the transformer I\'m using provides both the VIN and the +48V, so they already have a common ground; also, both VIN (+6V) and +48V are regulated (LM7806 and LM317).

[digistump]

Schematic attached - the mosfet is an FQP30N06L

Re: shield sales - as soon as we finish shipping the kickstarter orders we\'ll open a full store

[digistump]

R1 = 10k-100k
D1 = standard diode

the solder jumpers are just to allow pin selection

[DoktorJ]

Hey, thanks!  One question -- how do I view the full size picture?  The thumbnail pops up and shows a 1225x901 resolution, but clicking it does nothing  :-/

[digistump]

I just click on it to see it but here is a direct link: http://digistump.com/board/uploads/FileUpload/c9/070c97e05d51d063501036ceb03108.jpg

[DoktorJ]

Would this be a decent board layout for a MOSFET shield?  I figure it keeps the traces well-separated, the MOSFET can lay down to minimize vertical space usage (the diode and resistor are mounted vertically in the picture, though I just figured out an arrangement that lets me mount them horizontally too).

[digistump]

looks good to me - what software did you use for that?

with it hooked to P4 you can\'t use USB communication while it is in use, hook it to P5 and you can

that\'s some serious voltage - depending on your amperage you may want some extra cooling, the mosfet can handle a lot of current but it needs some serious cooling

[DoktorJ]

Photoshop  I have DipTrace, but it was on my other computer and I hadn\'t bothered to fire it up yet.

I don\'t intend to use the USB during operation (it\'s going to be a manually-adjusted PWM controller for a 48V fan) so the P4 conflict wouldn\'t be a problem.  The fan is rated at 0.75A and my power supply is fused at 1.5A so the MOSFET shouldn\'t ever see more than 1.5A (maybe a 2A spike just before the fuse pops ).  Should it need additional cooling at that current?

[Bluebie]

I\'d aim for p0 or p1 - they have similar pwm outputs and if you one day wanted to use USB with the mosfet shield you\'d be able to. Might as well make things as future proof as possible?

[digistump]

You should be fine on the amperage - especially with your nice cooling pad there

[DoktorJ]

Oops!  I almost forgot that I needed an input to control the PWM!  I\'ve added another header to carry +5V from the Digispark to an external 100K pot, then the pot\'s wiper back to the board.  Will P1 be sufficient for AnalogRead() ?  I\'m going to run +5V to the 100K pot and tie the other end to ground, which should make a 0-5V voltage divider that will play well with AnalogRead(), correct?

[digistump]

P0 and P1 do not have analogRead capabilities see the example here: http://digistump.com/wiki/digispark/tutorials/basics

If you flip over your digispark all the pins are labeled with their abilities - P2-P5 have analogRead

Otherwise this sounds good

[digistump]

I should add that on the back of the Digispark D/A stands for Digital and Analog capabilities