The standard Class AB audio power amplifier allows for direct coupling of the output of the amplifier to speakers. This is very good in that no capacitors or transformers get in the way of the sound quality coming out. The speakers are connected directly (more or less!) to the amplifying devices. This has the unfortunate side effect that if an out
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put device fails, this usually causes the raw DC power supply to be connected to the speakers. Most speakers burn out or are mechanically damaged by this very quickly. Protection circuits have been designed to prevent this kind of damage, and come in many flavors. They range from the simple - such as an added fuse in series with the amplifier output - to the complex, with all sorts of monitoring. The current favorite is a series relay circuit at the output of the amplifier, driven by some sort of DC detection circuit. Relays have their own set of problems, though, not the least of which is reliability. Relay contacts corrode, arc and stick over time. Worse, each time they are tested could well be the last time they operate, so there are some built in problems. Fuses are also problematical, as they must be excruciatingly well sized to offer good protection, and when that is done, the fuse resistance is modulated by the heat dissipated in the fuse near maximum power, so there are audible side effects. Some recent advances in power MOSFETs make them attractive for replacing or sidestepping relays and fuses on the output of the power amp. Power MOSFETs make good switches, changing from a totally nonconductive state to a fractional-ohm resistor in nanoseconds with the proper drive signal. Unlike bipolar transistors, there is no offset voltage or rectification associated with a MOSFET`s on-state conduction. As long as the current...
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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