This is yet another project born of necessity. It`s a simple circuit, but does exactly what it`s designed to do - dim LED lights or control the speed of 12V DC motors. The circuit uses PWM to regulate the effective or average current through the LED array, 12V incandescent lamp (such as a car headlight bulb) or DC motor. The only difference betwee
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n the two modes of operation is the addition of a power diode for motor speed control, although a small diode should be used for dimmers too, in case long leads are used which will create an inductive back EMF when the MOSFET switches off. The photo shows what a completed board looks like. Dimensions are 53 x 37mm, so it`s possible to install it into quite small spaces. The parts used are readily available, and many subsitiutions are available for both the MOSFET and power diode (the latter is only needed for motor speed control). The opamps should not be substituted, because the ones used were chosen for low power and their ability to swing the output to the negative supply rail. Note that if used as a motor speed controller, there is no feedback, so motor speed will change with load. For many applications where DC motors are used, constant speed regardless of load is not needed or desirable, but it is up to you to decide if this will suit your needs. First, a description of PWM is warranted. As the pot is rotated clockwise, the input voltage changes linearly with rotation. At first, the voltage is such that the comparator output is just narrow spikes, which turn the MOSFET on for a very short period. Average current is low, so connected LEDs will be quite dim, or a motor will run (relatively) slowly. As the input voltage coming from the pot increases, the MOSFET is on for longer and longer, so increasing power to 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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