As it turns out, many types of LEDs appear to exhibit gain effects akin to those of an avalanche photo diode when reverse-biased - an effect that has been observed in the 25-300 volt area with the voltage, spectral response, and overall sensitivity/gain depending on the LED`s construction and material. It is possible to adapt some of the circuits
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on this page to be used with an LED for experimentation of this gain mechanism. Not surprisingly, the degree to which this effect occurs and at what voltage tends to vary wildly from device to device as this is not a mode in which LEDs were intended to operate! The stability and long-term viability of operating an LED this way is another factor that should be considered. While the results do vary, some LEDs have been noted to offer reasonable performance as gain-enhanced detectors when operated in this mode making it practical to have at least moderate performance as a detector - a particular attraction if one wants to build an optical transceiver that uses just one diode for both receive and transmit. While an interesting phenomenon, tests thusfar seem to indicate that, at least for baseband (audio) use, the ultimate sensitivity of a typical LED operated in this mode is worse than that of a well-designed optical detector using standard PIN photodiodes. Having said this, this avalanche effect can be used to good effect to make an optical transceiver that uses the LED for both transmitting and detection and yield a single, compact package with reasonable performance. I`ve not seen "ultimate sensitivity" comparisons with PIN photodiode-based receivers and avalanche LED receivers for subcarrier (ultrasonic and up) operation. The circuits described on this page can form the basis of an optical receiver utilizing the avalanche...
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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