Electric Scooter Project

[3v0]

@3v0: My knowledge of PICs is pretty limited. Could briefly explain how the circuit looks and/or make me a quick sketch? Ill look into that cooler idea

It would be an interesting way to go and you would learn a lot. But if you want to get the project finished ignore me.... On the other hand you could always upgrade it with a PIC latter.

You program the PIC to produce a PWM signal to drive the mosfets. Other then the PWN signal coming from the PIC instead of the 555 the drive part of the schematic should be the same.

A variable resistor servers as a speed selector. The PIC reads the speed selector via an AD input. The PIC also knows how fast the scotter is moving by counting shaft rotation some place in the drive. The PIC adjusts the power (changes duty cycle) to make the RPM match the speed selector. The greater the difference between the actual and desired speed the greater the change in duty cycle will be.

 

[Ubergeek63]

why does it seem that everyone insists on using 555s instead of switcher chips that were designed to do this stuff?

 

[Willbe]

That little more should be your power mosfets in parralell to control the motor

I'm thinking with the inertia of the scooter & passenger you could use a relay run at 5 Hz with PWM; almost no switching loss and a long contact life.

 

[blueroomelectronics]

The arcing would pit the relay contacts in no time. Will make a horrible noise too.

 

[Willbe]

The arcing would pit the relay contacts in no time. Will make a horrible noise too.

The contacts would have to be rated for an inductive load, or use an R-C suppressive network. 10 million cycles at 5 Hz = hours/days of operation???
I'm thinking motor noise would drown out the contacts clicking.

On second thought, walking is better for health.

 

[3v0]

The contacts would have to be rated for an inductive load, or use an R-C suppressive network. 10 million cycles at 5 Hz = hours/days of operation???
I'm thinking motor noise would drown out the contacts clicking.

On second thought, walking is better for health.

What is the upside to using a relay instead of solid state parts?

 

[Hero999]

Sorry but it's a silly idea, it'll only last for 555 hours and 33 miniutes, most incandescent lamps are rated for nearly twice that and are much cheaper and easier to replace.

 

[Willbe]

it's a silly idea

I fired my ghostwriter!

But, at least now we know how long to make the warranty on this thing.