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# RESISTOR

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(@butch)
SLOTCARS
Joined: 3 years ago
Posts: 12
Topic starter

HOW CAN I GET A RESISTOR TO ONLY ROTATE 45 DEGREES AND ADJUST VOLTAGE FROM 0 TO 12 VOLTS?

it would be awsome if i cold adjust the resistor rotation to what i want in degrees. 45 to 60 degrees rotation.

i just do not know how to do it! i will need a high amp mosfet to run a 12 volt dc motor. so a low voltage to high voltage by the mofset.

if some one knows how to do this i would be real happy.

i was also thinking of useing a arduino and pwm adjusted by a rotating resistor or something that would work on a 45 degree maximum rotation.

help dronebot.

(@robotbuilder)
Member
Joined: 4 years ago
Posts: 1996

@butch

I was also thinking of using a Arduino and PWM adjusted by a rotating resistor or something that would work on a 45 degree maximum rotation.

And how are you going to physically restrain the rotation of the potentiometer (rotating resistor) to 45 degrees and why?

Yes you could use an Arduino to control the speed of a motor using a potentiometer (POT) there are many examples on the internet.  Another way is to use the 555 timer IC and again there are examples on the internet how to do that.

(@butch)
SLOTCARS
Joined: 3 years ago
Posts: 12
Topic starter

THINK OF A RADIO CONTROL CAR AND THE TRIGGER TO MAKE IT GO FORWARD IT ONLY MOVES LIKE A TRIGGER ON A GUN. YOU PULL IT BACK THE CAR GOES FORWARD LET GO IT RETURNS, PULL IT GOES FAST LET GO IT STOPS. A RESISTER MAKES CONTACT WITH WHIPPER BUTTON AND WILL GET DIRT OR CARBON ON IT AND HIT AND MISS. NO GOOD. SO A ROTARY ENCODER HAS NOTHING THAT TOUCHES AND IT MOVES REAL EASY! SO I HAVE BEEN LOOKING AND I THINK I CAN USE A ROTARY ENCODER AND SET ARDUINO PROGRAM TO MOVE IN SECTIONS. THAT IS WHERE I GET STUMPED. THERE IS 1024 SECTIONS BUT I WANT TO USE LETS SAY 50 OF THE 1024 OR 45 DEGREES AND SET THE VOLTS TO MOVE 1 VOLT FOR 4 SECTIONS = 1 VOLT, 8 SECTIONS = 2 VOLTS 12 SECTIONS = 3 VOLTS ALL THE WAY TO 48 = 12 VOLTS, I THINK I HAVE TO USE A BASE OR 0 TO 255 AND USE 25% OF THAT. I AM GUESSING IT COULD WORK LIKE THAT?

(@butch)
SLOTCARS
Joined: 3 years ago
Posts: 12
Topic starter

IF I USE A POT I DO NOT NEED THE ARDUINO CAN USE A MOSFET AND RESISTORS AND ROTARY RESISTOR. I NEED 50 AMPS @ 12 VOLTS.

THE ARDUINO I COULD DO A LOT MORE LIKE USE TIME TO RAMP UP THE POWER AND WHEN THE TRIGGER COMES BACK TO BRAKES I COULD PULSE THE BRAKES. JUST SO MUCH MORE ADJUSTMENTS IF I USE A ARDUINO! I JUST NEED TO LEARN THE PROGRAM TO DO ALL THAT I WANT.

PLUS I WOULD LIKE TO USE PWM AND SET THE FREQUENCY TO 3000 I SEEN A VIDEO WHERE DRONEBOT USED A HIGHER FREQ TO SMOOTH OUT THE MOTOR. I DO NOT KNOW IF THE ARDUINO CAN BE ADJUSTED ON FREQUENCY FOR PWM.

(@robotbuilder)
Member
Joined: 4 years ago
Posts: 1996

Most people find lower case letters easier to read.

Unfortunately I can't really work out what you want to do. What is the 1024 sections? The analog input values? Why voltages if you are controlling a motor with PWM?

I assume you have viewed and read Bill's bit on rotary pots?

(@butch)
SLOTCARS
Joined: 3 years ago
Posts: 12
Topic starter

maybe this is easier to explain,

((((( i want to use a rotary pot of 90 degrees that has a output of 0 to 5 volts CW rotation, ( it is a hall effect rotary pot )))))))

i can get the same thing 90 degree and output of 5 to 0 volts dc CW rotation.

i need a mosfet to run the motor because it will pull 50 amps @ 14 volts for 5 seconds max.

what can i use to make a dc motor start at 0 volts and move up in voltage at .1 volt increments to 14 volts dc total output. it does not have to be .1 it could be .5 increments to maximum voltage ( input ) if i had 14 volts max.

using a 0 to 5 volts or 5 to 0 to vary the voltage of 14 volt @ 50 amps. does a mosfet use voltage to vary the output high power voltage? i see everything to just turn on or off at 5 volts but nothing to vary the voltage.

i do have some pwm controllers that use a pot i will have to burn up something to find out how it works. reverse engineer.

i hope you under stand!

maybe i am to stupid!

(@centari)
Member
Joined: 4 years ago
Posts: 44

@butch, I hope I'm not coming across as a jerk, as I don't mean too.  It seems as though you have the solution if you start at the bottom of your last message and work up to the start.

Rather than thinking voltage 0 to 14, I'd recommend duty cycle 0 to 100 percent.  Start with the PWM controller, to drive the mosfet, which drives the motor.  The motor sees 14 volts all the time, but starting out just a small pulsing of time of it, building up to what ever percentage is needed for your top speed.

If you need reverse, put an 'H bridge' between the mosfet and the motor.

Another option might be an ESC.  electronic speed controller.  used by hobbyists in remote controlled cars and planes and drones.

Hope that helps some.

(@butch)
SLOTCARS
Joined: 3 years ago
Posts: 12
Topic starter

can i use a hall effect and magnet to make 0 to 100%

you just let me know how pwm works! it is full votage and just pulsed to go slower. like tapping a start button.

so does a hall effect to a mosfet trigger of 0 to 5 volts work to make a 0 to 100% pwm?

i am learning hope you do not think i am stupid. i think i am but i am trying to learn