We know that on the market there are plenty of devices that replace normal wall switches and let you adjust the luminosity of a bulb. But if you want to make an `intelligent` home or a more complicated device to adjust the power of a light bulb whatpossibilitiesdo you have 1. If you are using DC, than it`s simple: just use a switching element (
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a BJT or a MOSFET ). You just apply PWM (Pulse Width Modulation) and vary the duty cycle from 0% to 99% and you can adjust the luminosity of a lightbulb or LED or you can set the speed of a motor. If I would use a BJT to implement my application, I would have to consider that in the reverse active region thebehavior isdifferent from theforwardactive region. Because the application will be used at 50Hz(lowfrequency) to "drive" a light bulb (small load), and the maximum necessary current that will pass through it will be under 4 - 5 Amps, I have chosen to use a TRIAC. The same application can be easily modified(add some diodes) and can be used to drive high power loads(motors, heating elements, etc) using Thyristors. 1. The galvanic separation is used for safety. The transformer takes the 230V AC from the mains and gives on the output a voltage between 8 to 24V(which is safe tot touch). 2. Use the voltage from the secondary winding of the transformer to power up the uC, and also to detect de 0 crossings of the mains. To power up the uC we need DC, so we take the AC from the transformer and afterrectifying(which include a bridge rectifier and a capacitor for filtering) block we obtain DC voltage 3. The uC uses 5V. We take the DC obtained at 2, use it as an input for the 7805 integrated circuit. At the output of the 7805 we will obtain 5Vstabilized. We will use this voltage to power up the uC. 4. Zero crossing detector - it`s...
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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