Hello, guys! I gonna make a helicopter by myself using ordered small motors 5V 1.3A. I will power them through transistor and MOSFET. I've done two schemes can you help me to choose one of them?
Neither will work properly and the NPN transistor is not needed. Try something like this approach http://bildr.org/2012/03/rfp30n06le-arduino/
Thank you, 30N06LE is useful. But the MOSFET gotta be IRF7416. Arduino does not have enough power to turn this MOSFET on. I thought a lot and I think second scheme will be quite appropriate. Are there some more suggestions how to power MOSFET IRF7416 with arduino?
Shouldn't PNP transistor get connected to the minus of battery?
GRXG:
Hello, guys! I gonna make a helicopter by myself using ordered small motors 5V 1.3A.
Well I doubt its going to fly with those puny devices.
You need BLDC + ESC for the main rotor, tail rotor isn't too demanding though.
For flight you need motors which can generate thrust greater than the weight of the
motor + battery at the very least.
An RC forum is the best place to ask about sizing up helicopter parts, not here.
As far as switching an IRF... with an NPN (see attached.)
The value of the resistor from the collector-gate junction to +12 is subject to debate (argument) - so, tailor to suit.
hmm, interesting schematic, thank you a lot.
It's not perfect, but all you said you have are NPN, so that's about it.
Note that when the NPN is OFF the FET will be ON.
A better way would be to add a PNP to the mix to make a "high-side driver".
There are FET drivers ICs available (MIC4427).
Now I see (dangit!) that you have "5V" motors.
Well, if you do then the Load should be connected to 5V (not to 12V).
And that 5V should not be the Arduino 5V.
There are NPNs that can run 1A, 2A. You have not said what type yours are.
I gonna place the FET below NPN transistor to make FET being turn on when transistor is ON. My NPNs can only run 0.1A it is quite enough to power Gate of the FET. And I think the resistor between FET and power supply will become less in resistance in this case.
I don't know what you mean by any of that, but it doesn't take a lot of effort to sketch your idea out on a sheet of paper, take a pic of that and post it (as an attachment.)
That's it! When there is no current at the base of transistor then there is no current at the gate of the FET. I already assembled test PCB with guidance of my sketch which tomorrow will be tested for an efficiency.
That circuit is going to give you about 0.3V on the gate. No, wait, 0V, because you've grounded the emitter.
But the MOSFET gotta be IRF7416.
The IRF7416 is a P-channel MOSFET and is not intended to be used, or switched as you've diagrammed.
Oops, good catch. I looked at how it was connected and missed that it is a P-channel MOSFET.
polymorph:
Oops, good catch. I looked at how it was connected and missed that it is a P-channel MOSFET.
Actually you are right I should use the same FET as this but N - channel (I've chosen IRF7455) and check if it works. I grounded it through a resistor in order to make current fully flow out when transistor is OFF
Smacking myself for having assumed too much, I guess.
That's the datasheet.
See Fig. 1 , "Typical Output Characteristics"
Maybe I should go back to bed, or maybe school, but - Why is an NPN needed at all?
Well, I guess things are in flux. Good luck to all.
OK, logic level N-channel MOSFET, good. But why do you keep showing this +1V and -1V? What is that?
No driver transistor necessary unless you are doing high speed PWM.
ok, I decided to use N-channel IRF7455, but I little bit hesitate that arduino can trigger this FET without a transistor because Gate to Source voltage is -+12V as it represented in datasheet nevertheless I gonna try to use MOSFET without transistor. Also I do not know which fly back diode to use. I guess diode has to pass approximately 50V 2A current.
From the datasheet:
Ultra-Low RDS(on) at 4.5V VGS
6.9mOhm to 9mOhm @ 4.5V VGS
The diode should be rated for 2 to 3 times the maximum expected current, so you might want a 3A diode there. 50V is fine.