After some new experiments on sound analysis, I used a different design for the microphone amplifying section, that I am happy to share with you (From the statistics of Arduinoos, I know that sound capture is a topic of major interest for many of you). The whole circuit is supplied with a clean +5 to +12V, filtered by C5. The microphone (electret t
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ype) is biased through R7, R8, using a filtering capacitor C2 for removing some power supply noise. The active pin of the micro phone is connected to the first stage of an inverting amplifier (IC2B) via a decoupling capacitor which stops the DC component of the signal and all the AC component to go through. The gain of this amplifier is set by R3 and R4, with G=R3/R4. The non inverting input of the amplifier is set to avirtualground at half the value of VCC (typcally 5/2=2. 5V), so that the signal at rest is about half VCC and swings around this value. Halving VCC is performed by the divider bridge R1/R2, stabilized by C3 and C4. Lacking to install thesecapacitors may lead to an unstable output. The output of this stage is available at pin 7 of IC2B. Someapplicationsmay require an even higher gain, which is achieved by a second amplifying stage. This second stage uses exactly the same design than for the first stage; its gain is set by R5 and R6 [erratic spot on R6 and GND: do not connect]. It shares the same virtual ground as for the first stage. The total gain of the amplifier is the product of the gains from the two stages. BTW, why would we use two stages It is very important not to violate the bandwidth limit of the op amp at the highest frequency seenby the circuit. Practical circuits can include gains of 100, but higher gains could causethe circuit to oscillate unless special care is taken during PC board layout. It...
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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