The Wien-bridge sine-wave oscillator uses a light bulb to stabilize its amplitude. The circuit in Fig 1 doesn`t have a light bulb; it sports several enhancements that lower its distortion and generate a test signal pure enough for testing modern op amps and high-resolution A/D converters. IC1 and associated components form the Wien-bridge and func
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tion as a bandpass filter. IC1`s output goes to the voltage-controlled amplifier (VCA), IC3. IC3 acts as a "smart resistor" whose value the circuit continuously adjusts via IC4. IC2 adds the outputs of IC1 and the VCA and feeds the result into the bridge. These two op-amp inverters eliminate any common-mode signal that might limit performance. The circuit`s AGC loop begins with diodes D1 and D2. These diodes half-wave rectify the outputs of IC1 and IC2. These outputs are 180 ° out of phase; so IC4 sees a full-wave rectified signal through R1 that is proportional to the output signal`s amplitude. Integrator IC4 compares the average value of the rectified current to a constant current through R2. Any imbalance in these currents causes IC4 to output a correction signal, changing the gain of VCA IC3. The VCA`s gain adjusts the oscillation`s amplitude until IC4`s input currents are equal. R3 and C3 further filter the correction signal to remove harmonic components that would manifest themselves as distortion at the circuit`s output. D3 minimizes damage to C4 and C7 in the event of reverse polarization. The ac performance of C1 and C2 is critical to this design. I recommend polystyrene or polypropylene film types; and make sure you connect the outside plate as Fig 1 indicates. Mylar capacitors can degrade the circuit`s performance by 6 dB. C5 and C6 are peculiar to IC1 and IC2. They eliminate distortion arising from VBE...
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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