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Topic: LM317 Help (Read 6326 times) previous topic - next topic

Rogy

@Grumpy_Mike

Thanks! :D

I hope I'm not too annoying with all these questions :P, maybe something like this? http://www.nteinc.com/specs/2900to2999/pdf/nte2987.pdf

Could you also tell me what exactly am I look for? N-Channel MOSFETS?
Ordinary people pursue order, Ingenuous people rule chaos.

Grumpy_Mike

Quote
maybe something like this?

Yes very meaty, that would do.

Rogy

Alright! :)

Now, if only I could find that in Eagle :P
Ordinary people pursue order, Ingenuous people rule chaos.

retrolefty


@Grumpy_Mike

Thanks! :D

I hope I'm not too annoying with all these questions :P, maybe something like this? http://www.nteinc.com/specs/2900to2999/pdf/nte2987.pdf

Could you also tell me what exactly am I look for? N-Channel MOSFETS?


Mouser shows that at $7 a pop: http://www.mouser.com/ProductDetail/NTE/NTE2987/?qs=sGAEpiMZZMutXGli8Ay4kFfMPLZ9xW8yKOlRS6m%252bwN0%3D

Sparkfun sells a logic level N-channel power mosfet for a buck: http://www.sparkfun.com/products/10213

Lefty

Grumpy_Mike

I said it was meaty.  :)

Rogy

I found something a bit cheaper than the previous I linked and am not sure if it will work...

http://eu.mouser.com/ProductDetail/Fairchild-Semiconductor/FDP6030BL/?qs=sGAEpiMZZMutXGli8Ay4kBEMMAKgSkd8MdwkNnQ%2fGU8%3d
Ordinary people pursue order, Ingenuous people rule chaos.

Terry King

Hi,

Speaking Of FETS... I would like to decide best 2 or 4 power NFET and PFET to stock for use with Arduino...

I would appreciate your suggestions...

Two that have been suggested are:

RFP30N06LE "N-Channel Logic Level Gate Power FET"
FQP27P06 "P-Channel Power FET"

Also maybe a good TO92 or similar small Logic-Gate NFET for cheap routine replacement of small NPNs like 2N2222 ??

What has been working well for you???

I'll make these available at a decent price in my online store...

Thanks!
Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com

Rogy

Can anyone tell me what I must pay attention to when choosing a FET for using it to regulate voltage with Arduino?
Ordinary people pursue order, Ingenuous people rule chaos.

Grumpy_Mike

Turn on voltage, it should be rated at 5V and have a low Ron at this value. At most 0.01R.
It should be in a package that allows good power dissipation because as I said it will burn off the excess power.

Rogy

@Grumpy_Mike

So: N-Channel FET, TO-220, 5V Turn on voltage, low on resistance, low resistance drain-to-source, and of course, drain source voltage high enough and same for current ?
Ordinary people pursue order, Ingenuous people rule chaos.

Grumpy_Mike

Yes.
Quote
drain source voltage high enough and same for current

You will struggle to find one that is not high enough.

Rogy

I think I found something that will fit my needs: http://eu.mouser.com/ProductDetail/Fairchild-Semiconductor/FDP7030BL/?qs=sGAEpiMZZMvECErq9cesgOhjwE8m5zTM4sOaJqrLpIU%3d


Now for the (hopefully) last question: How do I connect everything? :P

Something like this?

                                                                      12V
                                                                       |
                                                                       |Source pin
                                                                       |
|Digital Pin 9|----|Resistor|----|Capacitor|--Gate--|MOSFET|
                                                                       |
                                                                       |Drain pin
                                                                       |
                                                                      Load(Fan)
                                                                       |
                                                                       |
                                                                       |
                                                                     GND
Ordinary people pursue order, Ingenuous people rule chaos.

justjed


Nothing against the LM317T. I once bought a barrel of 14,000 of them for $55 from a junkyard near IBM  :) I'll send 5 to anyone who'll send a SASE... I still have about 500 left.


Cool! Would 2 "forever" stamps be sufficient postage? Maybe 3 to be sure, eh?

Thanks, Terry.
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

Grumpy_Mike

No like this

                                                                     12V
                                                                       |
                                                                   Load(Fan)
                                                                       |Drain pin
                                                                       |
|Digital Pin 9|----|Resistor|-------------Gate--|MOSFET|
                                                |                     |
                                         |Capacitor|            |Source pin
                                                |                     |
                                                |                     |
                                                |                     |
                                                |                     |
                                                |                     |
                                              GND                GND

The way you had it:-
1) the capacitor would block the DC signal and nothing would get too the gate
2) you would not get any more than 5V across your fan

Rogy

Ordinary people pursue order, Ingenuous people rule chaos.

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