Hi! I'm using IRLB3034 MOSFET transistor to heat up a nichrome wire. I ran into a problem where I can't supply enough current to fully open the 3034, so it heats up the wire slowly. This part of the system is very time-sensitive and ideally it should heat up immediately. I'm considering using a PNP transistor to amplify signal from D4 pin. I only need a simple switch. I'm thinking S9012 BJT transistor can do this.
I did read about PNP transistors for a couple of hours, but still can't figure out how to calculate resistor values for the S9012. Correct me if I'm wrong:
I should connect Emitter to the power supply (5V)
Collector goes to the Gate of IRLB3034
Base should be equal to 5V for the S9012 to remain closed and at least 0.7V lower for it to open
I didn't sleep well and most likely I can solve this myself tomorrow, but I'm on a tight schedule. Please explain what resistor values I have to use to make this possible.
Please post a pic of a hand-drawn wiring diagram, with pins, connections and parts clearly labeled. Identify which MCU you have.
A MOSFET is a voltage-controlled device, but since the gate is a capacitor, there might be a problem with the switching time, if the voltage source has high internal impedance.
That's what I thought too. IRLB3034 shouldn't draw a lot of current from the Arduino pin. Sorry, I can't draw a wiring diagram at the moment, but I can tell how everything is connected, since the wiring is pretty simple:
Gate to A2 pin via 178 ohm resistor
Gate to Source via 12 kohm resistor
Source to GND
Drain to nichrome wire
~4V (li-ion battery) to nichrome wire
That's basically it. Why did I think that IRLB3034 needs higher current though? That's because I connected Gate to 5V supply directly and over the 178 ohm resistor as a test. And the nichrome wire lit up immediately. I did test A2 pin with multimeter, it does supply 4V just fine. The datasheet of the IRLB3034 suggests that 4V is more than enough to allow 20A through. Am I wrong?
The gate capacitance of the IRLB3034 is over 10,000 pF, so it appears to be a dead short to a digital output pin. If you don't use a current limiting resistor (or MOSFET driver), you can destroy the output pin.
Turn on time will be on the order of 2 us, for a 5V pulse limited to 20 mA.
Pencil and paper work well for making a schematic. Take your time.
No, it's not for vaping. Also, it works perfectly fine apparently. The circuit on my diagram is correct. I've looked at the diagram and then at my wiring, and realized that I connected 5V to VIN pin instead of 5V pin. I've soldered it to the correct pin and the nichrome wire heats up immediately. Sleep deprivation is the worst enemy, I guess.
You're right, even after solving the problem I wasn't able to locate any issues in the diagram above. Sorry for posting a wrong one! It's not easy to see the wiring on the actual photos because the project isn't flat but cylindrical – parts are connected around a li-ion battery holder via 3D printed holders. It's a parachute deployment system for my model rocket.
However, I can provide the correct diagram this time, here it is:
The system is rigorously tested by now and performs as expected. I just had to stop working and get some sleep instead of posting here.
The answer is pretty simple actually – the website that I made this diagram on doesn't have a voltage converter diagram. In reality both wires go from li-ion battery to CKCS BS01 boost converter configured to output 5V. I just can't show that on the diagram and I thought you would assume that the project uses common technique of adding a 5V converter between Arduino and li-ion battery.
The question was about increasing the current output of a digital pin, which turned out to be unnecessary because I've connected VOUT terminal of the converter to the VIN pin of Arduino instead of 5V pin. The IRLB3034 wasn't getting enough voltage on Gate to fully open. I understand that you might be worried that I connected something else wrong, but it's my 23rd or so Arduino project and although I never used MOSFETs before, I'm pretty confident that everything else in my project is wired correctly.
The topic is already marked as solved, the physical side of the project is also performing correctly. I've performed about 40 tests already and 35 of them involved heating the nichrome wire. So I don't see how drawing the diagram by hand would help me since I don't have any problems with the project. It was one thing that I missed and that's it. Thank you for caring so much, but I don't need any further help. Have a great day!
A proper and accurate schematic would be good.
The 5V supply, what are its outputs, where is positive and negative connections.
This thread could be of interest to another user, they might even have your problems with their code/hardware.
SO in the spirit of the forum, providing the final working code and schematic is appreciated.
NOTE: The forum members helping you are volunteers here, we are not payed, our knowledge is given freely and we expect in return your co-operation in the spirit of the FREE forum.
As I said, the 5V supply is CKCS BS01 boost converter. It has 2 inputs and two outputs. This way of powering an Arduino is standard and I'm sure this is not the topic that would open someones eyes when it comes to powering the board. The only common issue that is present in this topic is wiring your project wrong can result in unexpected results.
My project contains other components, but they're not relevant to the topic so I didn't add them to the diagram. The "powering Arduino" side of it is very plain and basic. It doesn't have any problems if wired correctly. The other side contains a MOSFET that is used to switch GND connection. It also works just fine if wired correctly. I didn't post any code because I was certain it has no issues, but here it is (unrelated parts are cut):
void deploy_parachute() {
analogWrite(16, 255);
}
I found a way to create the voltage converter, so here's the completed diagram:
The conclusion of this topic is: wire your project correctly and keep your sleeping schedule healthy.
