Lego Technic is perfect for creating quick prototypes of pretty much anything, combine this with RC stuff and you can create really fun stuff. One simple example is the robot i describe in this post: Sunday afternoon robot
My old Lego is usually stuffed away in a box in the basement, but when we have kids visiting we usually bring it up to the apartment. I suspect I’m the one enjoying it most and this time I built a RC lego car
From the side
The motor and propeller us used as a pusher
The battery, ESC and receiver is secured with a rubber band
I use a HXT900 servo to steer
After a few testruns I added a propeller protection bar to minimize the risk of running into something with the propeller.
Runs great, I’ll probably update this post with a video when I’ve recorded one.
Last weekend we borrowed a sewing machine to make new curtains for the apartment. When I was sewing the curtains I realized that It wouldn’t be very difficult to make a custom battery bag for my e-bike. I would like a bag that I could mount in the frame triangle and have room for 4 Turnigy 6S 5Ah batteries. Doing some measurements, calculations and drawing I came up with this design
An outline of the battery bag, the red triangle is the frame, the blue rectangles are batteries and the gray rectangle is the controller mounted on the frame.
I went to the fabric store and found a black nylon fabric that had a PVC layer on one side. This should be fairly water resistant and I plan to spray it with some textile waterproofing spray as well. I was recommended to use a thread for furniture which is much stronger than ordinary thread as well. A couple of hours thinking, cutting, and sewing later:
I use some Depron in the bottom, and some foam in the two corners to protect the batteries and fill out the bag.
The zipper has a bit of fabric folding over it for water protection
The hole for the cable is also waterproof since the side of the bag overlaps ~10 cm where the cable comes out.
I'm using the cable I made for the E-Puch. This cable is for two turnigy batteries in series and two in paralell with a 60A fuse. The LEGO part is just for size reference.
Everything fits nicely inside the bag
The bag fits perfect on the bike!
Battery bag on bike
Battery bag in frame
Pleas write a comment if you think I should make some kind of drawing and description on how to make a bag like this.
I had nothing to do today so I copied hubbens creation from the Swedish electronics forum. It is a two wheeled radio controled vehicle based on just two servos.
For wheels I used two wheels from an old Lego Technics truck I got for christmas almost 20 years ago (The best christmas gift I’ve ever got BTW). The wheels were bolted to servo horns from two HXT900 servos.
Servo horn bolted on lego wheel
The servos are glued together and self adhesive velcro is glued to both sides
These servos are modified for continous rotation according to this guide.
Open servo and remove the gears and potentiometer.
Connect to your receiver and set your output to center. (or use another way to generate a 1.5 ms pulse every 20 ms)
Adjust the potentiometer to the center until the motor stops and solder it so it can’t rotate any more.
Remove the stop pins on the output gear with a sharp knife
Sand the top of the potentiometer axis so the top gear spin easy on the axis.
Re-assemble the servo
The servos are then glued back to back and some self adhesive velcro are mounted on both sides and the wheels are mounted.
The ideal would be to run both the receiver and the servos of a 2S LiPo but I only have 3S at home so I needed to use a Turnigy 8 V – 10 V 5A SBEC to power the servos and the receiver. Together with the DC/DC converter the über cheap Hobby King 2.4Ghz 6Ch receiver was mounted on the top of the servos.
Top of the vehicle, the Turnigy SBEC to the left and Hobbyking receiver to the right.