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Topic: Slotcar speed controller with display and electronic memory project (Read 14212 times) previous topic - next topic


Altough the exponential power curve adding looked to be simple I am still working on it with help from other members here.
What I achieved in the meantime is regenerative breaking.

Normally when you like to break the car to reduce speed dramaticly you have to release the trigger to its zero position so the brake FET is switched on.

If you reduce speed by releasing the trigger the motor will have less internal braking and still carry high speed.

Now when you release the trigger and the speedValue is lower as the previous speedValue the brakes are ON and Speed FET OFF until the speedvalue of the trigger is level or higher again. This way you brake much later and does not have to release the trigger to full brake section. In the end this would save time and lower the lap time.

More to come

Never to old to learn and I learn every day


Did some more programming and added the QAB Quick Access Buttons for speedstart, speedcurve and brake on the controller handle.
The four red buttons are for the menu navigation.
Ordered BTS6143 fets ( High side smart N-channel fet) for the speed side and regular logic level N-channel fet for the brake.
Still a long way to go............... :smiley-sweat:

Never to old to learn and I learn every day


Two steps further.

Breadboard stage has gone and we have a working prototype ready to use.
The upper DIY MEGA shield contains the 4 buttons for the MENWIZ menu navigation and 4 indication LED's.
Two fets for speed and brake rated at 8 AMP continous mode each at the top of the shield.
Also the BT module is connected and working.
Wireless BT connection with the previous made Visual basic program is working too.
Next step is to communicated with the SMARTPHONE by BT and control en view the settings from there.

Never to old to learn and I learn every day


Update  :)

We are now a long way since the start but we are making progress.
We swapped the handmade controller handle for a ready to buy version.
The potentiometer who was giving eratic values during testing is replaced by a linear hall sensor and a 10x10x4 mm neodyne magnet.
The 6 six buttons for 3 selectable main functions up and down now have 4 neighbour buttons which control the menu navigation.
The cable to the Mega is a ripped USB cable with "+", "-" and the analog values wires for the hall sensor and the menubuttons which work on an analog port too.
In the picture all looks to be connected but the Mega the display and the button board are mechanical seperated still.
More to come.

Never to old to learn and I learn every day


An other step.
We are currently wireless connected from conroller to the LAPTOP PC by BlueTooth.
This is only one direction communication.
PC screen shows all available settings in realtime.
The power curve screen also shown in realtime.
Now we like to set the controller by the PC screen in the other direction.


Never to old to learn and I learn every day


We replaced the 20x4 for a 16x2 and connected it to button pcb.
We had to replace the USB cable for a 6 wire telephone flatcable to get the I2C through it.
We placed the BT modul on the shield.

Never to old to learn and I learn every day


Hi Paco,

:) Very Nice Project!!!

What Means Regenerative Braking and his values ???



Hi Steve,

Pull the trigger full to get full speed.
You reach a corner and have to reduce speed.
Now if you release the trigger fully it will brake to reduce speed like any regular controller.
When you enter the corner you have to pull the trigger again for let say 50%.
So you go from 100 to 0 to 50% to enter the corner.
This means lot of trigger travel and time.

Now with regenerative breaking.
You reach a corner and release the trigger to 50%.
As the regenrative brake hysteresys is set to 5% it will activate the break from 95 to 50% and then release the brake and go furhter with the speed of 50%.

So with this option you can brake later as you only release the trigger to the point you need to round the corner.
This reduces trigger movement time and also make the driving and control more smooth.
The hysteresys can be altered.

Now we also have speed brake.
If the trigger was pulled fully you carry more speed so you need more brake to reduce speed.
If the trigger was pulled 50% you carry less speed so you need less brake.

So speed brake is a speed dependable brake value.

Do you understand? :-)

Never to old to learn and I learn every day


Great !!!

Many thanks

When will be possible to see any "On Road Video" :smiley-eek: :smiley-eek: :smiley-eek: :smiley-eek:

I can't wait...  :D



Yes, Yes,

Went to the track last friday but Murphys law dictated.
All what could go wrong went wrong.
Bluetooth connection with my laptop failed.
Some loose wires shorted and blew the BT modul later.

So this week I reworked the controller mechanics and switched to an Arduino Nano.
So now all is on the controller board. Only the driving FETS are on seperate PCB.

See picture of the latest controller. Again use the handmade handle.

Satisfied?  :-)

Never to old to learn and I learn every day


Once again I have to park the project due to no time available.

Never to old to learn and I learn every day


I fully approve of anything slot car related. But with all the time invested in this couldnt you just learn to drive them properly yourself? :-):-):-)

Only Joking, But Im Oldskool scalextric, I Thought Magnets Were Cheating When they Came Out. 

I Have Been Mulling Over The Idea Of A Turbo Boost And Brake For Years, And Im Thinking Of Using Arduino To Do It Soon , Hopefully With a gyro To Give some Type Of Traction Control. But My Main Concern.

Wouldnt The Extra Weight In The Car End Up Making It Slower And defating The Point Of It.?

I Like The Chopping Board Idea.   I May Use That Kn The Future. 


The more i think about this, the more i miss playing With Scalextric.

I Hadnt Thought Of Having The Chip In The Controller, I Had Always planned To Have the Chip In The car And Measure Some Type Of Double Tap On The Gas To activate The Boost. 

I Assume Your Pwm Control Of mosfets Does The same Thing As The Variable Resistor In  The original Controller? Thus Being Totally Compatible With A Normal Scalextric Set?


   One way of keeping the weight low - as in low down where it helps rather than high up where it does not - is to use PCB as the chassis material. Lot of guys have done this in the past becuase its easy to solder home made chassis together this way. With a bit of though you could design an Arduino chassis.

Lots of examples here -

Duane B

Read this
then watch this


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