This is a project that I undertook during June 1996 as my final year electronics project. The entire circuit was built using individual components including logic gate ICs and and keyboard decoder IC. Since them electronics has moved on and if this was created today most of the functionality would instead be implemented using a microprocessor / mi
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crcontroller such as the Arduino prototyping board. This is however an example of how circuits can be designed using logic components. To set the alarm the supply must be disconnected. To achieve this a transistor switch is used to disconnect the supply when the full or part set switch is pressed. This is achieved using a NOR gate (IC2D). This is a 18 pin IC which uses a matrix output type keypad. The PIN number can be separately programmed directly from the keypad. This makes programming much easier. The pin layout is shown below. The IC is CMOS compatible and has a key-in echo, which bleeps every time a key is pressed. The following circuit would have to be fairly complex to use this IC. Below is the circuit diagram if the IC was for use as a door opener. The choice of the decoder was based on two main factors. The first was the required complexity of the following circuit. As the RS7225 gave fixed output levels the IC could drive combination logic directly whereas the UA3730 would require special sequential logic to decode the outputs. The second factor was cost. The cost of the two ICs is very much the same but the cost of the required keypad was much cheaper for the telephone type keypad. Also a membrane keypad was available for the telephone type which gave a level of waterproofing. As the RS7225 required the disconnection of the supply to reset the outputs a transistor switch has been used to disconnect the supply...
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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