If you want to learn Morse code and you don’t have a teacher, you’d probably just head over to a website or download a phone app. Before that, you probably bought a cassette tape or a phonograph record. But how did you learn Morse if you didn’t have any of that and didn’t know anyone who could send you practice? Sure, you could listen to the radio, but in 1939 that might be difficult, especially to find people sending slow enough for you to copy.
Wireless World for August 3rd, 1939, has the answer in an article by [A. R. Knipe] on page 109. While you probably wouldn’t use it today, it is a great example of how ingenious you can be when you don’t have an Arduino and all the other accoutrements we take for granted today.
Continue reading “Morse Code Keyboard 1939 Style!”
A team of Cornell students have designed and built their own electronic boxing trainer system. The product of their work is a game similar to Whack-A-Mole. There are five square pads organized roughly into the shape of a human torso and head. Each pad will light up based on a pre-programmed pattern. When the pad lights up, it’s the player’s job to punch it! The game keeps track of the player’s accuracy as well as their reaction time.
The team was trying to keep their budget under $100, which meant that off the shelf components would be too costly. To remedy this, they designed their own force sensors. The sensors are basically a sandwich of a few different materials. In the center is a 10″ by 10″ square of ESD foam. Pressed against it is a 1/2″ thick sheet of insulating foam rubber. This foam rubber sheet has 1/4″ slits cut into it, resulting in something that looks like jail bars. Sandwiching these two pieces of foam is fine aluminum window screen. Copper wire is fixed the screen using conductive glue. Finally, the whole thing is sandwiched between flattened pieces of corrugated cardboard to protect the screen.
The sensors are mounted flat against a wall. When a user punches a sensor, it compresses. This compression causes the resistance between the two pieces of aluminum screen to change. The resistance can be measured to detect a hit. The students found that if the sensor is hit harder, more surface area becomes compressed. This results in a greater change in resistance and can then be measured as a more powerful hit. Unfortunately it would need to be calibrated depending on what is hitting the sensor, since the size of the hitter can throw off calibration.
Each sensor pad is surrounded by a strip of LEDs. The LEDs light up to indicate which pad the user is supposed to hit. Everything is controlled by an ATMEGA 1284p microcontroller. This is the latest in a string of student projects to come out of Cornell. Make sure to watch the demonstration video below. Continue reading “Boxing Trainer Uses DIY Force Sensors”
Winter’s a-brewing and that is a downer for the everyday cycling enthusiast. There are certainly ‘bike trainers’ out on the market that will let you ride in your living room but they clamp to (or require replacing the) the rear axle. These bike trainers hold the bike in an upright position so that the rider can’t tip the bike and might feel a little boring for some. There is another indoor biking solution called a bicycle roller which is, just as it sounds, a few rollers on the ground that the bike wheels rest on and is not attached to the bike by any mechanical means. When the rider pedals the bike, the bike wheels spin the rollers. Even with the lack of forward momentum the spinning of the wheels is enough for the rider to stay upright.
[Sky-Monkey] wanted to bike during inclement weather and felt that a bike roller was simple enough for him to try building one. He likes building things and already had all the necessary parts kicking around his shop. The rollers are standard 3″ PVC pipe with plywood discs pressed into each end. The discs are counter-bored to accept standard skate bearings. Off the shelf steel rod make up the axles. The 3 rollers and axle assemblies are mounted in a wood frame made from dimensional lumber. It’s important that the front bike wheel also spins so [Sky-Monkey] made a power transmission belt out of cloth strap that spins the front roller with the rear.
The result is a fully functional bike roller that only cost a few hours of time to make. Video of this puppy in action after the break….
Continue reading “DIY Bicycle Roller Helps Cure The Winter Blues”
Our cats are not allowed on the kitchen counters, and [Iron Jungle] has the same rule. But he spotted some foot prints on the hood above his range and the addition of a security camera caught this picture of [Kelso] breaking the rules. Since he’s not always around to make the fur-ball behave he built an electronic cat trainer to do it for him.
The functionality needed isn’t very intricate. You need to monitor when the cat is where it shouldn’t be and then chase it away. For the latter he grabbed an infrared range finder. When the cat passes in front of the sensor it will trigger the second part of the system: a high-pitched buzzer that’s extremely loud. Any microcontroller will have no trouble driving the system. In this case it’s a PICAXE 28X1.
You can see the trainer in action after the break. It definitely works, because just playing the video chased our own sleeping kitty out of the room.
Continue reading “Cat trainer will keep them off the counters”