This project was used to introduce a friend of mine to microcontrollers and circuits. I wanted something that used a variety of microcontroller functionalities and used only parts that I had lying around. I ended up using a PS2 numpad as the key entry mechanism since it was what I happened to see in the thrift store, and it happened to come with t
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he connector it mated to. I left the decoupling capacitors off without any ill effect, and you could most likely get away without a pull up resistor on the reset circuit. The 220uF capacitor was a must though. Without it the servo would cause large dips in the voltage causing the microcontroller to reset. Originally, I had the microcontroller drive the speaker through a resistor, but this turned out to be too quiet to hear through the book. To fix this I added a MOSFET to allow a larger current than the microcontroller could output directly. Writing the code turned out to be extremely easy. The arduino IDE comes with libraries to handle producing tones and controlling servos. I was also able to find a library for PS2 keyboard. A couple of things to note using these libraries: TheIRQpin specified for the keyboardcorrespondsto the externalinterruptnumber of the pin you attach the keyboard`s clock signal to. I originally specified the digital pin number which was incorrect. Since I didn`t want to actually waste an Arduino on this project, I ended up soldering the components directly to an Atmega328p. I had an AVR programmer so I could have just directly programmed the hex file produced by the Arduino IDE, but I decided to burn on a boot loader to make future updates easier. I followed the guide here using theminimal configuration. Unfortunately, the board. txt file that site supplies seems to be for an older version of the...
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.....
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