24 replies to this topic

[Dante]

I need a slot car controller based on Arduino with speed control and brakes. The motor speed is controlled with an H-bridge but the brakes are the problem. The brakes must be adjustable from no brakes to full brakes and everywhere in between and is controlled by a pot...

 

A schematic and sketch would be very helpful.

 

Does anybody have some ideas?

[Dennis David]

That's a good question though I'm not sure how much help you would get on this forum. Have you checked out any Arduino forums?

[Dante]

I've checked Arduino, Adafruit, and SparkFun but no luck.

[Cheater]

Dante,

 

Dennis has given you good advice IMO.

 

I am not an electronics guy and was unfamilair with Arduino, so I did a little searching.

 

Based on your last post, you've not found an existing solution to what you desire. If I was in your shoes, I would post a question regarding what you seek in this Arbuino SUBFORUM. Perhaps there are other fourms worth posting to as well.

 

Seems most are using PWM for motor control in this arena, and that's not been very successful for slot car use to the best of my knowledge.

 

Just one question: you said you 'need' a slot car controller based on Arduino. Is this not a 'want,' rather than a 'need'? (That's a conversation I often used to have with my two sons: the difference between wants and needs. LOL.)

[Markomatic]

What would the advantage be of running a controller with Arduino? Hall effect on the trigger as a position sensor?

[Dennis David]

I think you need to ask the question on what you want the brake effect to accomplish with regards to voltage and not mention it's for slot cars, etc. 

[Bazzie]

Slotcar speed controller with display and electronic memory project

Why specifically H-bridge? Do you want to drive the motor in both directions? I assume it's not for slot car? For slot car typically only use a high-side MOSFET driver, and for brake you switch another MOSFET in that shorts the motor positive down to ground.

You could in an H-bridge just switch on both transistors on the low side to brake the motor. Pulse them (PWM) and you have a variable brake.

And BTW PWM works fine for slot car controllers.

Some people have referred to delays with PWM but that certainly was not because of PWM per se, that must have been due to other design problems with the specific controller.

[Cheater]

And BTW PWM works fine for slot car controllers.

I'll take your word for it, Even, but at least in the 1/24 arena I'm not aware of anyone making a PWM controller that is seeing a lot of use or recommendations.

[Bill from NH]

In the early 2000s we had a software engineer who prided himself as an electronic techie. He built a PWM controller for his son & brought a Tectronic oscilloscope to the raceway on race nights to tweek its tuning. I would say its performance was marginal at best. He promised controllers to others, but never delivered. After about a year, he disappeared from this area and his controller design went to some cloud.

[MSwiss]

Did we ever get a reason the OP needs such a device?

[Bazzie]

A South African guy I know sold 140 of his PWM controllers in SA. Back then it was a PIC micro controller based circuit using a tapered tinted piece of perspex in between an IR LED and receiver, essentially maintenance free and very smooth.

I've not gone fully commercial with my controller by choice, but I have made a few for friends. They are too labour intensive the way I make them at the moment to bother, and I only just sorted what I hope to be the last of the teething problems after I made some design changes. One of the fast guys at our club reckons he's faster with my controller than with his other unnamed but very popular controller.

[Zippity]

... One of the fast guys at our club reckons he's faster with my controller than with his other unnamed but very popular controller

 
Oh, who would that be then?
 
I don't see anything showing up in our latest race results.

[Bazzie]

You know.

[Zippity]

If it was such a superior controller, wouldn't he race with it in all classes?

[Bazzie]

No one said superior! I just quoted him! It's his choice what he wants to race with it. A controller is a very personal thing. If you ever played golf you would understand the analogy to a putter - it's a matter of taste.

 

People that have tried my controller liked it. And this is not about my controller anyway, it's about PWM, that's the point I was making. Just as there are good and less good instances of analog controllers, so there are good and less than good instances of PWM controllers, and that's the point I was making...

[Bazzie]

And to further clarify, I was not saying mine is the best PWM one or better than analog either, I am not deluded!! All I'm saying is that PWM per se is not the problem, it can be done well!!

[CDavis7]

It's been done. The major problem is that the Arduino needs to power up before it's operating. The brief time it takes to power up means your car is stationary for a bit after every track call while everyone else has taken off. The only way around this would be a 5v battery connected to the controller, which would not be legal.

[Dennis David]

PWM Controller

I've used his non-PWM controllers and they were great so I would not bet against this guy. May not work for open wing cars but should work for everything else.

[Dante]

Thanks, guys.

I got more postings from this forum than all the others in total!

[Samiam]

I'm impressed with the technical knowledge assembled here.

 

I thought Arduino was a former Argentine president.

[Cheater]

This is a perfect example of why Slotblog is a better place for slot car enthusiasts than those social media sites.

Yes, I am biased... LOL!

[Dennis David]

And no pictures of kittens.

[Samiam]

Till now...

[Dennis David]

You mean if I hook this up to my controller it wouldn't be legal?

[Bazzie]

Ha-ha, Sam!

Regarding boot-up time, on my smarter controller I do run a battery. It falls within Aussie and I think British rules, some others not according to the letter. There is however no way that my controller can apply either more power, or power while track power is off. We had another thread some time ago about controllers and batteries.

There is in fact a problem with pretty much most modern controllers in that they contain capacitors as smoothing/filtering to keep noise in the circuits to a minimum. The rule says controllers are not to store voltage. Most do, so by that rule all controllers that contain any capacitors violate the rule. I queried it with our local NZSCA and I was allowed to use my controller in the nats last year.

My lower-end controller does not use a battery, but I disable the bootloader and make sure that I switch on power early in the power-up sequence if the trigger is pulled, and yes, there's a very small delay, perhaps 20ms, hard to measure, but because I run pretty deep into the corners. I was right with the group last week when I raced with the backup. Just a fraction behind, which is not a bad thing, better to not get tangled up in the first corner.