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### Topic: Doghouse automation design advice (Read 6676 times)previous topic - next topic

#### x2dz

#30
##### May 10, 2011, 11:39 am
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Since this is about automating your dog ..sorry the dogs environment
- Haha... Still on that, are we?

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how come your tutors at uni haven't been able to review your design.
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I have asked on or two of them if they could take a look at it, but I thought I'd try here in the mean time and iron out anything stupid I'd done

p.s. Besides some of them are wonderfully helpful if you ask them stuff about the lecture they just presented, but if you take them a little out of their comfort zone (for example hitting a problem they're not certain about), they tend to get short with you if you know what I mean...

#### x2dz

#31
##### May 14, 2011, 10:45 pmLast Edit: May 14, 2011, 10:46 pm by x2dz Reason: 1
Here's the latest PCB mock-up...

Thinking of going into production soon

#### x2dz

#32
##### May 25, 2011, 12:49 pmLast Edit: May 25, 2011, 12:59 pm by x2dz Reason: 1
Hi guys,

I'm currently selecting the MOSFETs for the design and would like to hear your opinions on whether the IRL1004 is a good match

The largest load will roughly be around 2.5-3Amps@12VDC - this will be the motor, driving the awning for the houses. I don't think it will run for longer than 15-30 seconds at a time.

This Power MOSFET is in a TO-220 package, has a R DS (on) = 0.009 Ohm with a  V GS = 4.5V (it is a logic level MOSFET) and according to my calculations should have no problems whatsoever handling the task it will be performing (and I'll more or less be wasting its potential on the sub Amp loads - valves, etc.). I used P = I (of the load)^2 * R DS (on) .

The only thing that puzzles me is that there are two Power Dissipation figures mentioned in the sheet - one is approx. 50W (for the TO-220 package, in the beginning of the datasheet) and the other is 200W as a Maximum rating for the FET. Shouldn't these be closer to each other?

I'm attaching the component's datasheet and would be greatful to hear your opinions. I will, of course, be running practical tests prior to ordering in quantities, but nevertheless - better safe than sorry

Thanks again in advance!

#### x2dz

#33
##### May 25, 2011, 01:51 pmLast Edit: May 25, 2011, 03:08 pm by x2dz Reason: 1
p.s. Would I be able to get away with using IRL2203N or IRL3103 or even a IRL540 FET since I don't really need the power of the IRL1004 (plus they're cheaper)?

I'm attaching their sheets

10x

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