This is a revised version of my LM35 based digital thermometer project that I posted last year. Although it is one of the simplest projects, it is very popular among newbies who are just starting to learn microcontrollers. There was a little flaw in the original project as pointed by some readers. I was using a 1. 2 V reference for A/D conversion w
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ith PIC16F688 microcontroller. However, the PIC16F688 datasheet says Vref should be equal to or higher than 2. 2 V to ensure 1 LSB accuracy of A/D conversion. Here, I am rewriting the same project but this time I am using a MCP1525 IC to generate a precise 2. 5 V reference for A/D conversion. This will improve the accuracy of temperature measurements. The LM35 series of analog temperature sensors are produced by National Semiconductor Corporation and are rated to operate over a -55 °C to 150 °C temperature range. These sensors do not require any external calibration. The output voltage is proportional to the temperature, and the temperature-to-voltage conversion factor is 10 mV per °C. The sensor does not have any DC offset output voltage (which means the output is 0V at 0 °C temperature) and therefore, a negative voltage source is required in order to measure temperatures below 0 °C. For simplicity, the setup shown here is made to measure temperatures above 0 °C only. The PIC16F688 microcontroller reads the analog output voltage from the sensor through one of its ADC channel and derives the temperature information out of it. For the maximum temperature value of 150 °C, the output voltage of the sensor would be 150 x 10 mV = 1. 5 V. If we use Vref = 5. 0 V (power supply voltage) for A/D conversion, the resolution would be poor as the input signal goes only up to 1. 5 V. Besides, if the supply voltage is not stable, it won`t...
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....
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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....
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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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