Hello everyone! I need a circuit for a high current voltage regulator based on lm 317 and a 3 2N3055 power npn transistors because that is the best I've got at the moment. I need it to regulate a wiper motor which I've modified to pull a cart up the hill. The hill is not very steep. Right now when I connect it to a car battery it goes way too fast. The cart weights about 30 KG when loaded. I've found a couple of schematics but I didnt find if anyone had actually build them, so I need some help from you more experienced guys.

 

How about the example in the datasheet?

 

I suggest mechanical gearing first. You want the cart to move at an acceptable speed when the motor is running full out. This will give you great torque and make it much more likely that you can pull a load up a hill.

If you reduce speed by reducing voltage, it will dramatically reduce the power available to the motor and it will stall when overloaded. Depending on circumstances, this could burn out the motor windings.

If, after the gearing is right, you need to slow the motor even more, you could use a voltage regulator. But you'll need to handle a lot of heat dissipation in those transistors and you will still have the issue of lost power and torque as you slow the motor.

Some motors can be controlled by pulse width modulation (PWM) and this is superior to linear control (which is what a voltage regulator accomplishes). Less battery power is lost as heat, and motor torque is maintained. You can buy online very inexpensively motor controllers using PWM. Just be sure its specifications far exceed whatever current your motor requires.

 

I second Wayneh's suggestions.
You don't want to use a linear regulator to control the motor.
PWM is likely the way to go.