The circuits looked at so far depended for their functioning on linear feedback. The magnitude of the signal returned to the negative input was always strictly proportional to that of the output voltage. The result was that within the limits set by the op-amp, the magnitude of the output voltage is proportional to that of the input signal. Often w
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e want to create a more complicated response. For example, During this lab you will examine two circuits, one in which non-linear feedback is used to achieve a particular response or transfer function, the other uses non-linear feedback to stabilize the amplitude of an oscillator. It is most convenient to analyze its function by considering separately what happens for Vin>0 and Vin < 0. Figure 2a shows the equivalent circuit for Vin > 0. In this case the diode D1 is reversed biased and effectively an open circuit, D2 is conducting. The feedback loop is effectively a single resistor, from the output of OA2 to the negative input of OA1. OA1 and OA2 act together as a single op-amp and the complete circuit acts like a simple voltage follower, Vout = Vin. There is a complication with this circuit. At sufficiently high frequency, both OA1 and OA2 introduce 90 phase shifts, which together with the 180 shift achieved by feeding the signal back to the input of OA1, would make the circuit unstable. A small capacitor, C, is used to counteract this. Assemble the circuit, initially with C = 100 pF, and check that it works as advertised for various wave forms (f = 1 kHz). Increase the frequency until you can clearly observe the problems that arise when the circuit switches over from Vin < 0 to Vin > 0 mode. What is the typical switching time Can you improve this by changing C Observe that without C the circuit becomes...
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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