This thermometer uses an LM19 sensor calibrated for measuring a wide temperature range (-55 130 Celsius, -67 266 Fahrenheit) for outdoor temperature measurement and an SHT21 digital thermometer with humidity measurement for indoor use. An ATmega328 microcontroller is used to read the temperatures from both an analog sensor LM19 using an analog input pin and a digital sensor
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SHT21 using the I2C bus. Since SHT21 uses 3V logic while the rest of the circuit uses 5V logic, a voltage translation circuit is necessary to interface SHT21 with the MCU. I used Taxes Instruments s PCA9517 level-translating I2C bus repeater as the voltage level shifter. The voltage shifting circuit is shown below: The SHT21 sensor is mounted on a breakout board and connected to the MCU board via a short cable. The LM19 sensor is encapsulated in a section of heat-shrinking tube and connected to the controller via a stereo cable. The cable length used can easily be extended to as long as 30 feet as long as the load capacitance is less than 300pF.
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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