Hi!
I am very new to microcontrollers etc. and I was wondering why Arduino Output Voltage ist mostly restricted to 5V but the majority of circuits I have seen use a power source with more than 5V..
So why do you use a higher input voltage, when the arduino can only give an output of 5V anyway?
Thanks in advance!
I use higher input/output volts when I need to measure or power something that uses greater than 5V's or less that 5V's. I use the proper interfacing electronics as needed.
Why not use 5V or 3.3V or 1.8V as logic standards?
Your topic was MOVED to its current forum category as it is more suitable than the original as it is not an Introductory Tutorial
Do not confuse supply voltage and logic voltage for control signals. Microcontrollers never directly control the power of high-power devices, they use low-voltage logic signals for this. The logic levels used in most professional devices are 1.8v, 3v3 and 5v
Because other components in the circuit require a higher voltage, for example 6V motors or 12V led strips.
Or because that power supply is the only one available or convenient.
If you have your choice of power supply, and no components in your circuit require a higher voltage, then you should choose a 5V power supply and connect that to the 5V pin on the arduino (not the Vin pin or the barrel socket).
Not all Arduino are 5V devices, many newer designs are 3.3V and can be powered by a 3.3V PSU if no higher voltages are required for other components.
So if I have components that require more than 5V, what do I do?
What exactly is low-volatge logic signal?
The arduino is NOT a power supply. Forget about the voltage of the arduino. Your loads eg motors, led strips etc need their own power supply. That supply can be any voltage you like to match the requirements of your components
Logic level is simply to describe that the arduino output is only designed to control other parts not power them. Logic is eg on/off and is a signal that will make other components switch the higher voltage/current supply.
Describe what you want to do and then we can explain in specific terms rather than generic
Supply it with the appropriate voltage.
any signal less than 0.7V
I don't think you know enough about what you are asking about to make much sense. So tell us what you want to do and we can tell you at the level of detail you need to know.
well, I have a shape memory wire which requires 6V of voltage supply.
The arduino provides PWM control to the mosfet gate and the wire is connected to the mosfet drain.
It just confuses me that the voltage output is 5V, but apperently you can still control devices that require more than 5V
As described the microcontroller uses logic level voltages which are normally 5v in arduino with some exceptions to 3.3V which is more modern. This is because the microcontroller is not designed to power anything it is only the “brains” and the pins output a signal which you take and use to control (not power) your more hungry components. Look at transistors and mosfets and you will see from their data sheets what the voltage has to be on the base/gate to allow low resistance through the attached power lines.
Voltage is not the only thing to think about. Arduino output pins can only handle small currents such as that used to drive a single LED.
Imagine a person in a massive excavator. The person does all the thinking and only has to move some small levers but the excavator does the heavy lifting. Arduino == brains. Heavy loads == pile of dirt
Be aware you need logic level mosfets as otherwise your arduino might not have the power to turn them fully on
Because the mosfet's a switch, that happens to be operated by 5V (or other voltages for other models of mosfet), and the voltage that's being switched can be any voltage up to the rating of that particular mosfet.
The voltage on the mosfet gate operates an internal switch between the mosfet's drain and source. The gate's really just like your finger on a mechanical switch.
Or am I misunderstanding your actual question?
Fixed it for you.
I have 3V3 ESP32's controlling 12V motors.
I've never used muscle wire but I'm pretty sure it's controlled by current, not voltage. They are related.... Current depends on voltage & resistance.... Resistance is "the resistance to current flow" and Ohm's Law says Current = Voltage / Resistance.
The wire will have a specified Ohms-per-foot (or Ohms-per-meter) so a longer wire will need more voltage for the same current.
Your power supply needs to be capable of supplying the current. A power supply puts-out a (relatively) constant voltage and the current depends on the load. (With nothing connected the voltage is there but no current flows.) If you draw too much current the can burn-up the power supply.
You should not power the muscle wire, or a motor, etc, through the Arduino. They can share a power supply but each should have it's own connection to the power supply.
Here is a MOSFET driver circuit shown driving a 12V motor. I assume this is similar to your circuit except the voltage to the MOSFET & load can be higher than the Arduino power supply. (Since your wire is non-inductive you don't need the flyback diode.)
If you have 12V on an Arduino input (like if you want to connect to an existing switch in your car) you can use a voltage divider (2 resistors) or an over-voltage protection circuit to knock-down the voltage going into the Arduino.
If you want to make connections to (dangerous & lethal) AC power you need complete electrical isolation. This can be optical isolation (like a solid state relay) or mechanical isolation (like a regular electro-mechanical relay). I have some sound-activated lighting effects that use AC light bulbs and solid state relays. There are relays with 120V or 220V coils and these can be uses with 5V on the contact-side if you need AC power as an input-signal to the Arduino.
'Tis a deep subject to jump into in a forum post. I think Sparkfun does a good job at explaining Logic Levels for TTL and CMOS devices.
Logic Levels - learn.sparkfun.com
What is often lost in discussions is that some devices like junction transistors are "current" driven and other devices like FETs are "voltage" driven. This is just a hi-level, general view. What this means is that a uC with a 20mA output limit can only drive a power transistor to a particular load current (V * I = Watts) and increasing the power driven through the transistor requires more current from the microcontroller's output port.
Using a power FET, the gate voltage drives the FET power transfer:
okay so this is my circuit right now. The current required will be approx. 3-6A.
The power supply is just a schmematic to show that I am using a labroratory power supply.
I'd appreciate your opinion to the circuit layout 
Hi,
Why do you have the Sources of your N-C MOSFETs connected to the 5V pin of the UNO.
The Sources should go to gnd.
How are you powering your UNO?
What are your "Gate Drivers"?
Thanks.. Tom... 
Oh yes the source should be pinned to GND, sorry!
the power is supplied by the labroratory power supply connected to Vin of Arduino.
I thought Gate Driver might be necessary to overcome large input capacity and voltage of mosfet that can‘t be provided by Arduino output. And addition to that Gives additional current to gate of mosfet for faster charge/discharge
--> Less heating, less power dissipation
Not for a simple load like this. If you want to protect your Arduino then a 120R series resistor will do in this case.
Are you going to supply the FETs with PWM? Than would be the only reason for switching faster. But I see you are not wiring them all to PWM capable pins.
Likewise the diodes across the metal are not needed, these are only required with inductive loads. Likewise the zener diodes across the FETs are not needed.
yes actually I want to control the fets with PWM. I thought the pins are all connectred to PWM..? Sorry I have never worked with Arduino before
I thought that with PWM and fast switching voltage, a TVS Diode over the mosfet might be necessary to protect it from voltage spikes. And the Flyback Diodes over the wires to protect them from damages due to voltage spikes.
No only the ones with a tilder mark ~ next to their name.
No need for any diodes because your load is not inductive, voltage spikes only come from inductive loads.
