another PWM question

[mazur50]

I have made posts in the past about other questions and i love the help you give.

here is my other question. In my question to get a edge in local slot car racing. i want to build a controller.

what i want to do is have something like this and adapt it to my slot controller
Click here for circuit. (http://www.oceancontrols.com.au/motor_controller/KT-5195%20Manual%20Circuit%20and%20Wiring.pdf)

But i want it to have brakes. and i really want to stay away from any kind of pic as i dont have a way to program them.

I will also post a pic of the track wireing.

So what i am looking for is to make a control that uses a mosfet for varable motor control and for brakes.

let me know if you can help

thanks a bunch your the best.

[calvino]

I have made posts in the past about other questions and i love the help you give.

here is my other question. In my question to get a edge in local slot car racing. i want to build a controller.

what i want to do is have something like this and adapt it to my slot controller
Click here for circuit. (http://www.oceancontrols.com.au/motor_controller/KT-5195%20Manual%20Circuit%20and%20Wiring.pdf)

But i want it to have brakes. and i really want to stay away from any kind of pic as i dont have a way to program them.

I will also post a pic of the track wireing.

So what i am looking for is to make a control that uses a mosfet for varable motor control and for brakes.

let me know if you can help

thanks a bunch your the best.
ok, a simple controler with a brake, can it use a mc (micro controller), one way to make brake work is to have a seperate switch (if that is allowed) or a dual direction handle like with a radio transmitter??? that maybe your best option :confused:

[mazur50]

A micro Controller is ok if i dont have to program it. I am not to good with code. and i dont have a way to program it.

and it needs to handel 16-18 volts and 40amp spikes.

and i would like to be able to make the brake variable, and also the sensitivity like the controll i attached.

[TheSteve]

If you don't want to use any kind of microcontroller you should probably stick with what you have. The wiper with a bunch of resistors driving a transistor is well tested design that is popular and works very well.

[mazur50]

I was looking to cut down on weight. and heat.

[Malc C]

Maybe you could adapt one of those circuits used for controlling model trains that have a throttle, coast and break functions. These use descrete components so no need for a PIC programmer. I'm sure if you google "train controller" something will be found

[rmteo]

There are several designs here with brake that do not use a microcontroller:
http://www.math.niu.edu/~behr/RC/speed-ctl.html

[jeffs555]

Most of the ESC type speed controls need one side of the motor connected to the positive supply and use an N-channel mosfet to pull down the other side of the motor. That is different from what you show where one side of the motor is connected to negative supply and you need a mosfet to pull the other side up. You would have to modify most ESC type speed controls to use a P-channel to drive the motor and an N-channel for the brake.

Here is one circuit using a comparator and other discrete components that could be easily modified. http://www.stefanv.com/rcstuff/esc.htm
To drive it with a pot, you would eliminate the input transistor and its associated components up to C2 and wire a pot as a voltage divider to supply a variable voltage across C2. You would also have to swap the N and P channel mosfet inputs, swap C4 and R11, change the direction of D1 and probably swap the inputs to Z1B.

[TheSteve]

If you do decide on PWM be sure to use a frequency in the region of 1Khz, if you use 60Hz PWM on a slotcar motor they tend to overheat!

[mazur50]

how do you change the Hz on the esc.