Using an Atmel ATTiny2313 microcontroller and an HD44780-compatible character LCD display, along with a reed switch and some magnets, I was able to construct a tiny speedometer/trip computer for a soapbox derby cart. It measured the speed of the cart using a permanent magnet attached to the rear wheel`s rim, and a stationary reed switch attached t
Click here to download the full size of the above Circuit.
o the soapbox derby cart. Every time the wheel revolved, the magnet would pass by the reed switch, thereby momentarily opening it. The microcontroller calculated the speed of the cart simply by dividing the circumference of the rear wheel by the period of the wheel`s revolution. This project was motivated by a problem I heard about from a friend. At the Burger King where he works, employees should take no longer than three minutes to build a burger; however, at his Burger King, no way to measure your burger-building time was supplied. Initially, I suggested buying a watch or an egg-timer from the local dollar-store, but I was soon reminded of why that was not a great solution: it was too easy and rather boring. The timer had to do one very simple thing: it had to count down from 3. 00 minutes to 0. 00 minutes and then beep. Consequently, I designed it to be very easy to operate. It had just one button - a very large, red one - that the user would press to turn on the device and start counting down from 3 minutes. Pressing the button while the count was already in progress would simply reset the count to 3 minutes. When 3 minutes elapsed, the device beeps for 1 second, and then switches to a low-power mode. I used a 32. 768 kHz crystal and a PIC16F84A microcontroller as the heart of the device, taking advantage of the PIC`s low-power "sleep" mode so that one-button operation would be possible. There is no need for an "off"...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: