Audio metering is present in almost any equipment that plays or records audio from cell phones displaying bar graphs of audio output levels, to home stereos with flashing LEDS, to live broadcasting. There are multiple standards for audio metering that deal with the levels being monitored and time constants used for calculating the average. The
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behavior of volume unit (VU) meters is defined in ANSI C16. 5-1942, British Standard BS 6840, and IEC 60268-17. These standards define 0 VU = +4d Bm, with an integration time of 300 ms. Traditionally, with a moving needle meter, this means that from zero signal to 0 VU, the needle should reach 0 VU within 300 ms (same for decay). This makes a traditional VU meter excellent for getting an idea of loudness, but a poor method for monitoring transients. This was fine in traditional broadcast and recording systems, mainly based on tubes and tape, both of which tend to saturate elegantly. In today`s digital systems, clipping inputs or outputs sounds awful, so peak program meters (PPM) are used. PPMs are similar to VUs, but, integration time is much faster (typically around 10 ms). Note that there are multiple standards bodies with definitions for the signal levels and exact integration times. Display technology is a big part of these standards. Getting the ballistics right to move a needle through 90 degrees (or more) with one percent of accuracy is much harder and slower than lighting a few LEDs! Using LEDs, the quality of audio monitoring varies drastically. For example, a simple voice recorder product requires a different metering system from a mini-micro system using LEDs as a visual effect. In a live sound or broadcast environment accuracy is important, as well as seeing the difference between average loudness and 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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