Home made automatic ping pong ball thrower

My kids and I are working on an automatic ping-pong ball thrower. We’ve come to the following design, which uses two rollers (paint rolls) being turned by separate motors. The laser-cut frame is supposed to also hold a servo which lifts the ball into the rolls, possibly controlled by sound-driven electronics. We’ll see where it ends up. wpid-20140114_222109.jpgThe files for lasercutting your own are here and here. They are licensed under Creative Commons Share Alike.

Creative Commons License
Laser cut ping pong ball thrower by Lars Kristian Roland is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
I’ve used InkScape to draw them.

Controlling motors with an MSP430 (or Arduino)

John asked a question about how to control motors from an MSP430, so I thought I’d make a post about it.

Quick overview

First choose motor type. If you use modified servos, you can just connect them to your microcontroller (MCU) and upload the right code. If you use plain DC motors you need a motor driver chip or board, such as the L298. You probably want geared DC motors, since they aren’t as fast as non-geared ones. Connect the driver to your MCU and upload the right code. The speed of the motors is controlled using pulse-width-modulation.

Software-wise you can either choose Arduino (or the MSP430-equivalent called Energia) or go for the C-approach. C is more difficult, but maybe more powerful. Arduino/Energia works great for many robots and I used this for several years before I moved to C as a programming platform.

Read on if you’re interested. More details and instructions below.

Continue reading Controlling motors with an MSP430 (or Arduino)

Kid DIY snowmobile (snow scooter)

I’ve made a snow-scooter for my kids, using motors from Allelectronics.com. It’s running on a 12V battery, though the motor is rated to 24V. It doesn’t go very fast, but I guess that might be a good thing. With a higher voltage lipo battery, I guess it’d be faster. Maybe I’ll make an electric car this summer, using a better battery.

I’m planning to add a h-bridge based motor controller, controlled by an Arduino. I’ve got the motor controller made, but I’m wondering how to do the mechanical speed adjustment (the throttle or pedal). The video shows the first run. The design is a bit ugly, but it’s just a prototype at this stage. I wanted to know whether the motor was actually strong enough. It is, but it struggles up hill or in loose snow, so I’ll check out some better batteries.

The steering wheel is attached to a ski that’s for a kid’s sledge.

Continue reading Kid DIY snowmobile (snow scooter)

What to do with motors?

Some months ago I went wild buying motors from allelectronics.com. Some of them I’ve used for some toy projects for my kids. But most of them I haven’t used yet.

I bought some really tiny motors (I didn’t know they were so small). I’m planning to make some really tiny remote controlled cars.

Lots of stepper motors (for the CNC, but I ended up buying proper ones from another source).

Some big ones. The plan was to build a car for the kids that they could sit in and drive around in.  Or build a segway… Could I build an electric toy snow scooter? Would it work? I haven’t gotten around to making the motor controllers as I haven’t had enough time.

The motors are just lying around, and I need to do something with them. I’ll do some projects when I get the 3d printer, and I really want to get started on the ‘soap box car with a motor’ for the kids. Those motors are really cool.

Right now I’m working on making a GSM enabled watch, and a watch for kids. I’ve been quiet for a while, but it’s because I’ve been setting up my company and have been a consultant at customer premises doing some embedded projects. That gives me less time for the fun ‘home projects’.

Any suggestions to projects are welcome.

ROV Done

The ROV is done, and it worked. Navigated really well. Only problem was that thruster to bring it up and down burnt out at some point, so I have to replace it. I think I’ll build one from a motor myself rather than using a bilge pump. I made a separate page with some pictures. It looks slightly better than the first version.

1st version of ROV (mini submarine)

I’ve followed various instructions on the internet, such as submarineboat.com, homebuiltrovs.com and others. It’s built from an IKEA shelf 🙂 but I’m planning to make it more beautiful eventually. I’ve got two versions of the controller, one just using switches and one using an Arduino Microcontroller. Using a USB extender over network cable for the camera.

I got a bad itch from the epoxy. Please be careful with that stuff. Use better gloves than I did.

Not tested in water yet 😐 (the floats aren’t shown in the picture).

Update 1: Check the separate ROV-page on the left. 

More info on this ROV will follow later Continue reading 1st version of ROV (mini submarine)