homemade speed controlllers (for school project)

[dtengineering]

There is some great information on speed controllers and design at:

http://www.mcmanis.com/chuck/robotic...sc2/index.html

In fact I recommend the entire site for those interested in robotics and electronics.

Jason

[Don Reid]

I wanted to try some experiments with small motors and a processor
producing PWM signals. I found a nice H bridge circuit at Digi-Key,
the LMD18200 from National. You feed it a pwm signal and power
for up to 3A at 12-55 volts. Of course you need a heat sink and some
filter caps at those levels.

[Denman]

Originally Posted by Denman

havn't decided yet, it depends how hard it is to make one go backwards....
ideally yes
having im'ed mike betts, i'm probably going to be starting this in a couple of weeks (given other stuff gets sorted as well...) and there will m/p be a thread about it then

i saw a couple of weeks
i mean a few weeks more from now.... seem to have got overloaded with other stuff ...

[greencactus3]

if you know how to use a servo, and understand the concept of resistors and how to read the lines you can make a clumsy mechanical real easy.

[sanddrag]

Originally Posted by greencactus3

if you know how to use a servo, and understand the concept of resistors and how to read the lines you can make a clumsy mechanical real easy.

The problem with that is that you are not pulsing electricity, you are converting electricity into heat. The lower the voltage (speed) the higher the heat. You are making a constant power draw. The difference is the ratio of heat energy to kinetic energy.

So what I'm basically sayingis generally speaking a mechanical speed control will run down the battery faster than an electronic one, and it will get very hot. Electronic is better.

[greencactus3]

So what I'm basically sayingis generally speaking a mechanical speed control will run down the battery faster than an electronic one, and it will get very hot. Electronic is better.[/quote]
yea i know but its so simple. not sure he said he was going to use a battery actually. if its unlimited power supply and littel heat isnt a problem id just make a mechanical.

[Adam Y.]

What type of motor do you want to use and what am I going to use this motor for is the most important question that you probably need to know. Moving a heavy object involves the use of a motor that we all know and love. Moving an object with percision would benefit most from either a stepper motor or a servo motor. If you want a motor that is going to last a long time brushless is the way to go.
Here is a website that I obtaind from searching google about speed controllers:Website

[Denman]

Hi again all

an update
I decided to make something easier for my school project, however there is a couple of people from the lower year who would like to make a couple, for this event. http://www.extremefightingmachines.c...cambridge.html
Basically we don't wnat to use any of the first equipment due to how expensive and precious it is, so we will be using a remote controlled car reciever, and a couple of home made speed controllers. The reciever gives out a pwm output to whatever it drives, and we used it beforein a previous featherweight, but with 2 victors.
So firstly, we need to decide how much current and what motors etc it will drive. They will most probably be window screen wiper motors, from a local junkyard. Anyone who would like to help and suggest stuff is most welcome, and it would be great to see a FIRST team thrash the destruction style teams
Denman

[Al Skierkiewicz]

Stephen,
I am not sure how your cars are laid out but in the US, the motor drives both wipers and is relatively powerful. I would guess it may run stall current as high as the Chalupa or Drill motor, about 100 amps. Your homemade controllers should be designed to handle that much current.

[Justin_302]

The game looks fun

good luck!

[Richard Wallace]

Stephen,
One option might be to use a chopper circuit from a cordless drill. An example is DeWalt part number 152274-10, Switch, VSR, available at www.dewaltservicenet.com for US$41.14. You would have to make mechanisms to actuate the trigger and reversing switch, but that might be simpler and cheaper than building your own compact high-current motor speed controller.

Good luck.

[Denman]

Originally Posted by Al Skierkiewicz

Stephen,
I am not sure how your cars are laid out but in the US, the motor drives both wipers and is relatively powerful. I would guess it may run stall current as high as the Chalupa or Drill motor, about 100 amps. Your homemade controllers should be designed to handle that much current.

last year we used some from a ford fiesta, they ran fine on a victor 554... the may not be a robot to put them in now.... depends what happens on this wednesday, as we havn't started on it. but we'll see
Right now i'm just researching some basic therory