The brief with this project was to produce cost effective electronics that could be assembled by a small, informal PCB manufacturing plant based in India, repaired easily, and producible with the minimum of setup. We used `jellybean` (common/generic/low cost) parts for this project whereever possible. While it would have reduced component count to
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place the A/D converter, watchdog, and EEPROM within the microprocessor, by keeping them external we could use a microprocessor that was very simple and basic, and for which very cost effective programmers were easily available. This project was all about making the board easy to manufacture with the least amount of setup and angst. The A/D receives the signal from the matching psensor pcb which conditions and amplifies the pressure sensor signal. The A/D converter we chose is a very simple part using the +5V rail as the A/D reference and providing an 8 bit parallel output which is read onto a port of the microprocessor which is coincidentally also the data bus. While the A/D converter provides an interrupt output, it is not used. A simple octal latch runs all the relays on the board, with the clock to the latch (continuously running when code is executing correctly) also feeding the watchdog circuit, and the output of the watchdog circuit also clearing the latch. In this fashion, should the code stop operating correclty, the watchdog will fire and clear the latch, clearing all the relays to the "off" state. We have a standard I/O bus that you can learn more about called Picobus. This board uses circuitry that is very similar to Picobus to multiplex the LEDs it drives, however there are sufficient outputs on the CPU to run the multiplex select lines directly, so one 4017 chip is omitted. Using an octal flip flop and 3...
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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