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Topic: 12v vacuum and arduino (Read 382 times) previous topic - next topic

spiderpro2003

Hi I purchased this Vacuum: https://www.sparkfun.com/products/10398

I also picked up this mosfet: https://www.sparkfun.com/products/12959

I have an Arduino MEGA and I was wondering if I could power this vacuum using a 12v 4.5Ah battery.

Also if I were to be able to use this battery with the Mosfet to power the vacuum on and off how would I wire it. Thanks.

tatersalad

Hi I purchased this Vacuum: https://www.sparkfun.com/products/10398

I also picked up this mosfet: https://www.sparkfun.com/products/12959

I have an Arduino MEGA and I was wondering if I could power this vacuum using a 12v 4.5Ah battery.

Also if I were to be able to use this battery with the Mosfet to power the vacuum on and off how would I wire it. Thanks.
To do what? turn on and off? why not use a switch? I appreciate the links but we also need some background on what your plan of use is and your thought process for the arduino.

neiklot

It says under Documents that pump is 12W, so at 12V that's 1A, more at startup if that's the "running" power. I don't know how to get the stall or startup current, given the running current, but it's probably about 5A or so for a short while. (Don't quote me.)

So you need to check if your battery can provide that current; the Ah you quote is capacity, not the current it can supply.

In principle you would hook it up like this:




spiderpro2003

Sorry for not specifying.  Yes, I simply want the Arduino to be able to turn the vacuum on and off.  The reason I am not using a switch is that I have preexisting code that I want to activate the vacuum.

tatersalad

Sorry for not specifying.  Yes, I simply want the Arduino to be able to turn the vacuum on and off.  The reason I am not using a switch is that I have preexisting code that I want to activate the vacuum.
now it all makes sense. yes the mosfet will run that pump just fine. As far as a wiring diagram its super simple check out the spec sheet and you will be switching the ground. The motor will connect to battery positive. I don't recommend using a 4.5ah battery. If its a sealed lead acid you "should" only drain it down halfway. But that all depends on your uses. let me know how the progress is coming and ill try to help you the best I can.

neiklot

Wow: a dollar for the actual mosfet and 4x that for the board....


neiklot

Don't. Forget. The. Diode.


TimChPi

It says under Documents that pump is 12W, so at 12V that's 1A, more at startup if that's the "running" power. I don't know how to get the stall or startup current, given the running current, but it's probably about 5A or so for a short while. (Don't quote me.)

So you need to check if your battery can provide that current; the Ah you quote is capacity, not the current it can supply.

In principle you would hook it up like this:




Um ... Didn't the board already supply a Gate grounding resistor?
Just wondering, I know it won't do harm to have another.

Also, anyone got any idea what is the gate-source diode doing in RFP30N06LE?

RFP30N06LE datasheet

Cheers

neiklot

I confess to not opening the mosfet link until after my post with the pic, and didnt realise it was a breakout with pull down, I just saw the word "mosfet". Digrams correct at the component level of course.


TimChPi

I confess to not opening the mosfet link until after my post with the pic, and didnt realise it was a breakout with pull down, I just saw the word "mosfet". Digrams correct at the component level of course.


It's technically correct in any level lol. Nothing wrong with 5k pull down. I'm just saying.

Any idea on what's going on with the MOSFET's GS Diode?

Paul__B

Wow: a dollar for the actual mosfet and 4x that for the board....
What board is that?

Um ... Didn't the board already supply a Gate grounding resistor?
What board is this?  Where is/ was the link to a board?

The gate grounding resistor is to keep the FET switched off when the Arduino is reset and its pins are effectively inputs and may float.  Since this problem belongs to the Arduino rather than the FET, the resistor should be across the Arduino pin to ground.  If it is on the FET gate, after the series resistor, then it tends to form a voltage divider and reduce the voltage turning on the gate.  That may be a minor effect, but it makes sense to avoid even minor impediments to performance.

Also, anyone got any idea what is the gate-source diode doing in RFP30N06LE?
To protect against ESD (Electrostatic discharge).

neiklot

What board is that?
This one:

Quote
I also picked up this mosfet: https://www.sparkfun.com/products/12959
That's a breakout board, not just the bare mosfet.


Paul__B

Ah yes, when I looked I saw only the FET sitting there.  :smiley-roll:

wvmarle

Any idea on what's going on with the MOSFET's GS Diode?
The body diode you mean, between drain and source?
That's just there. Part of the MOSFET construction. Can be useful (in e.g. H-bridges and level shifters). Most of the time it's just there, not doing anything, like in case of a simple switch.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Paul__B

The body diode you mean, between drain and source?
He did say gate-source.

In the datasheet, such a diode - two back-to-back Zeners - is shown.

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