These tiny little 6cm long cars are available almost everywhere these days and cost usually around 10 euro / $15 / Â£7.
There designed for kids to be used in kitchens and operate via 4 buttons to turn and go forward and back. However as standard there almost uncontrollable and only have one speed - fast as possible. So time to do what I do best.. and make it better!
Remove the shell via the 2 screw under the car and you'll find a tiny PCB with a 100mAh battery controller over 27/40mHZ.
So rip all that out except the motor and leave as much motor wire on as you can. Inside the steering assembly you'll find a copper coil wrap and 2 magnets, also remove these but keep the steering unit intact.
Now to extend the chassis and gain control over the steering cut the chassis into 3 pieces. The motor should be cut off just where the motor ends.
The front end steering TURNS AROUND so keep the piece where the 2 screws hold the top plate in.
I made my chassis 6cm long and turned the wheels about to find out how much clearance they required.
Using regular super glue I applied generously before bonding the parts to the plywood.
A comparison photo to show the increase in wheelbase over the stock model.
Now that the steering unit has done a 180 degree turn the steering linkage faces inside the car where you can make a connection. I used a servo horn cut down and again used regular super glue to bond it.
For the servo I used a cheap $3 hobbyking micro servo (4.2g) and cut down a steering horn to below the minimum hole and made a new hole. The reason is you want to save space but also you only need a TINY bit of servo movement.
The car needs a speed controller and I used a servo control board with pot still attached. The reason is the servo motor is the same as that in the car and therefore perfectly fine. A servo can turn a motor both ways so we also get reverse!
The servo, with the electronics removed and finally wrapped up ready to use.
I'm using a Fr-sky 4 channel Fasst receiver which I've removed from the case and trimmed all the pins short as possible. Then I've direct soldered all cabled to the RX including the power plug and a spare power line for the FPV gear.
I am using Elevator for throttle as it self centres which is what we need for forward / reverse.
Steering I have placed on rudder control for the same reasons although you could use ailerons if you wanted it all on one stick (when using mode 2).
Show how much clerence there is for the steering servo once the RX is laid in place on foam pads.
Obviously the original shell is not going to fit on when the FPV gear is in place and I don't want to risk damage to the electronics. I worked out a lorry type shell would house everything except the lipo battery.
Inside you can see at the back I've cut away part of the original car shell where the chassis used to screw in. I cut out a plate piece and glued it onto my new shell in the same location. Now the lorry shell can screw in from the bottom.
Some paint, varnish and decals later.
Here you can see how the chassis fits in so far and the screw that keeps everything in place.
I cannot get myself to a hobbyshop to pick up some scalectrix tyres but the front wheels need to be a bit thicker to stop bottoming out. I used some bungee line cord cut into tiny segments to wrap over the original tyre increasing the thickness by just 2MM overall diameter and it works.
Now the 5.8ghz 8 channel 10mW video transmitter needs soldering. The power cables and video line are pretty simple.
Same deal for the camera with power lines and a video line connection.
The video cable goes directly from camera to video transmitter.
The power lines get linked up with the front lights I added from the original car all in-line.
To keep the shell removable from the chassis I used 2mm bullet plug connectors that are small enough to fit inside the cabin when the shell gets put in place.
The finished product next to a standard lighter. The lighter is longer than the truck lol.
With the lipo on the back of the lorry velcro in place the power goes on, lights flick on and we have video and a fully working lorry!
With the lights on you can still see the lights I added are working like fog lights projecting a beam across my desk.
This project is not finished though! This is only one of two and potentially later up to 4 conversions all designed to do one thing.. Race!
To do that we need a race track! well.. it's in progress :)