I have made use of a IRFZ44N MOSFET (as a switch) without using a driver, and it works directly from the Arduino. However, I am aware that it is far from ideal. Also, I was using a 1k gate resistor, because I was worried about excess current from the output. I know it should ideally have about a 100 ohm resistor and a voltage between 10 and 15.
I have researched various sites to get some idea for a circuit. There tended to be too much waffle, and not much indications of basic circuits. I therefore just threw together a basic circuit based on the most simplistic arrangement. It is all working with no problems (hence I have not included a photo of the wiring due to this). The wiring is not the issue but I am not sure if my circuit is too simplistic, and maybe needs some extra resistors, or anything else.
I have a feeling that maybe a resistor in about 10k range should be between BASE and ground, and GATE and ground, but I am not sure. I also have a feeling that they are intended for something like avoiding float, but I am also not sure!
Feel free to add any details. It is all good.
Additional: That LED load could very likely be something with high current like a solenoid. The MOSFET has a very high current capability, hence it is ideal to drive things like 12v solenoids, with no issues.
Oh… and I have just worked out from the circuit that there is the possibility that all that high current is going to go straight through the BC337 as well! This cannot be right… I think I may have done something totally silly
If you have noticed that the circuit is complete nonsense, then you will likely be correct!
Yes I have just worked out that the circuit is complete nonsense. It is completely stupid, yes. Do you know of some direction/ sites, or info that would help to create a sensible arrangement that does what I am trying to do?
I simply want to drive the MOSFET via the BC337. I have just now been trying to get the collector of the BC337 to drive the gate, which I am pretty certain, is what I was supposed to do in the first place!
The circuit is complete silliness. The collector should actually be supplying to the gate. It is a complete disaster, when I realised that I could simply disconnect the 13 volts… and it was still blinking.
That's not even near "simply". Use a logic level MOSFET and drive it from a GPIO output. Add a gate current limiting resistor and one that keeps the MOSFET OFF with disconnected gate.
So this seems to be going full circle then. I am actually back to square one with just driving the MOSFET directly from the Arduino. I was under the impression that ideally the MOSFET should have between 10-15v going to GATE, and with a 100 ohm resistor.
In answer to that, the MOSFET can handle larger currents. That was the ultimate goal, and to avoid using a power relay. I have done a circuit with a power relay directly from the BC337. The BC337 cannot handle a solenoid, for example. The IRFZ44N can easily handle a solenoid, because it can go to currents in the high 40s of amps.
Indeed the MOSFET can be powered directly from the Arduino, but the GATE is far from turning on fully.
AH! I got it. I was confused by the lettering, and you are recommending a different MOSFET. I got confused with the one letter difference, as in the “L“. Understood now, thank you.
Eureka! Now it all makes sense! The only little difference is that I utilized the 100 ohm resistor between the collector and the GATE in your provided circuit diagram.
I really appreciate the advice, but just one thing. Do you think that the 100 ohm resistor is required? I just noticed you left it off, and maybe it is superfluous.
I can indeed see now that the 5k resistor is making sure that all that current is no longer going through the low current BC337 of course. This was probably my main source of confusion. To get the 12 volts to the BC337, and hence the GATE.
I will bear that in mind. This is mainly for solenoids, due to the high current. I would not be using PWM for solenoids because it is just the fixed 12v I need to drive it.
Oh, thank you again. I can just invert using the programming then. I have just altered the blink delays in the program, and I can see what you mean now. Great!
Just to clarify, a gate resistor in series is to protect the Arduino pin for overload, not the mosfet. Since there is no Arduino pin connected to the gate in diagram post#13...
Leo..
As @Wawa explained it about the gate current, if you look the 4K7 is now the current limiting resistor when Q2 turns off and the gate is pulled to 12V.
Yes I have just worked out that the circuit is complete nonsense. It is completely stupid, yes. Do you know of some direction/ sites, or info that would help to create a sensible arrangement that does what I am trying to do?
