There are two major types of backlights for LCDs: LEDs, which stands for light emitting diode, or EL, which stands for electroluminescent. EL backlights tend to be more efficient and have more uniform lighting than LED ones, but they require some tricky circuitry to drive. If you`ve heard of Organic LED displays, or OLEDs, that`s basically an arra
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y of electroluminescent strips shunk down to the size of individual pixels. Every kit shipped before 4/07/2009 has an LCD which actually includes an electroluminescent backlight. Kits shipped on 4/07/2009 or newer have an LED-based backlight, so this video does not apply. Electroluminescent backlights are hard to drive because they actually require about 100 volts AC at around 150 Hz, and we`re just running our logic off 5 volts DC. But we can use an inductor to generate these high voltages. After a current is allowed to build up in the inductor, the switch is opened. The fundamental device law of any inductor is V=L*dI/dt, where dI/dt is the change in current per time. So if the current is asked to change from something to zero basically instantly, a huge voltage will be present. (For our actual circuit, we measured a 300V peak and roughly 100mA of peak inductor current, which means dI/dt=3, 000, 000 Amps/second, or switching off in about 33ns! This matches well to the 22ns rise time listed on the IRF730A datasheet. ) Whenever the voltage on the unconstrained end of the inductor is greater than the voltage across C1, diode D1 lets charge flow and further charge C1. This is basically a peak detector, finding the maximum to make a smooth DC signal. The 100K resistor guarantees that if Q2 is open, the electroluminescent panel will have zero voltage across it, because the 100K resistor will discharge the very small capacitance...
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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