For the most part we live in an analog world and when using a microcontroller, it is often necessary to be able to convert a digital value into its analog equivalent (or, for that matter, an analog value to a digital value but that`s not what this post is about). Many of the low end and low cost microcontrollers available today do not implemen
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t a built in hardware digital to analog converter (DAC). However, most do contain an 8 bit or 16 bit timer that is capable of producing Pulse Width Modulation (PWM). Pulse Width Modulation is primarily used to control power to a load such as a motor or a lamp by varying the pulse width (duty cycle) of a fixed frequency square wave. The load responds to the average voltage that represents the duty cycle of the waveform. Increasing the pulse width will result in an increase in the average voltage level to the load along with a corresponding increase in the motors speed or the lamps intensity. However, Pulse Width Modulation, in conjunction with a simple resistor and capacitor (RC) filter, can also be used to generate specific DC voltage levels or various analog waveforms such as sine or triangle waves (also referred to as Direct Digital Synthesis or DDS). As an example, to produce a DC voltage that is 50% of the MCU`s supply voltage, it is only necessary to output a waveform that has a 50% duty cycle and filter it with a simple RC filter. In a similar manner, to produce an output voltage that is either 25% or 75% of the supply voltage, the duty cycle is changed to either 25% or 75%. It should be noted that the PWM frequency used should be as high as possible in order to keep the values of the RC components small. Accurate sine waves can be created by using Pulse Width Modulation, an RC filter and a look-up table with 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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