This design was born of frustration with the mic preamp in my Sony R91. It clips at ridiculously low levels, basically it has 28mV of headroom to deal with an input that could be as high as 1800mV (depending on mic & volume), so this design attempts to cure that by : B: Having much greater preamp headroom, and bypassing the R91`s mic preamp altoge
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ther, using a hi-fi or low noise op-amp to go straight into the line input. The circuit needs to bring the signal from an electret microphone up to a level suitable for a line input. Based on measurement of the microphone output under a range of conditions, I have chosen tw1o gain levels - 2 & 23. 23 is suitable for everyday general recording. 2 is suitable for live music such as a rock concert. There is a output pot to allow fine-tuning of the level if necessary, but it is intended that usually the wiper will be on the land. When choosing an op-amp, it`s important to find out the open loop gain at 20kHz. The circuit has roughly 27dB of gain, and at least 47dB at 20kHz (i. e. 20dB higher) is desirable. This is because op-amp circuits are predicated on an ideally infinite open loop gain, while in reality 10 times (20dB) higher than the closed loop gain at highest frequency of interest is acceptable. Otherwise the amplifier becomes progressively non-linear. The TL072 at roughly 45dB just makes it. The LM833 is good at »55dB and the NE5532 sparkles at »60+dB. If you`re going for ultra small size, you can build it single supply rail, but an LM833 won`t run like that. A TL072 will, with reduced output swing, it`ll swing about 1. 8VRMS off a single ended 9V supply, which is adequate for the purpose. Otherwise tw1o 9V batteries will do the trick. Now about these solid aluminium capacitors - in some respects very good capacitors,...
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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