Hello, do I have to use Mosfet within below circuit? I think, I can control the motor speed only via a potentiometer?
Thanks.
You do not need a mosfet if all you want to do is run the motor from the battery. BUT YOU DO NEED A WIRE WOUND POT that will handle the current!!!
Paul
Thanks Paul fro your response. Then, what is the aim of the using mosfet in this circuit? I am totally confused.
If Your pot is intended for signal current, not any power pot, You can use a mosfet. Add a gate resistor to avoid burning the pot in the end stroke.
If you had intended to include an Arduino in the project, why did you not include it in your diagram?
What is the purpose of mosfet in this diagram?
If it was a BJT ,(which by controlling the base current , you can achieve control over the current flowing through the collector-emitter path.) The pot will serve to control the current through the motor , hence the voltage and the speed of the motor
But for a Mosfet ,
If you ask me , the mosfet can replicate the action of the BJT but this time by controlling the voltage across the gate -source you can achieve control over the drain source path
Thanks elijah, then I guess, if there will be controlled only pump speed, we dont have to use the mosfet with the pot in thiscircuit. only the pot is enough for adjusting the motor speed.
I think it is a bad idea and will not work well, either with or without the MOSFET. It will not give a good linear control over the motor speed, especially at low speeds. The pot must be high-current, as mentioned above. Normal pots will burn out quickly. Battery life will be poor, even when only using slow speeds.
This is why PWM drivers are used. If you don't want to use an Arduino, you can use a 555 timer chip or an attiny chip if something more sophisticated is required. With either chip, you will need the MOSFET, and if using Arduino or attiny, it must have a logic-level gate.
Unless the pot is a large beefy wire-wound open-frame one designed for high current and with a low resistance (a few hundred ohms), no, you'll simply fry the pot track.
Standard potentiometer tracks (carbon film) are limited to 10's of milliamps usually, and the wiper contact prefers very little current for a long life. Cermet pots are a little more robust, but only wirewound can handle significant amounts of power.
But my question is why are you not using an Arduino and PWM to do this, given this is the Arduino forum!!
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