The input coupling capacitor allows the input signal to pass through to the grid of the tube while preventing the input source from potentially shorting the grid bias to ground. If the grid bias were shorted out, the 6AG7 would overheat and it would be destroyed. The value of this capacitor is not critical at all. As long as the reactance of the c
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apacitor at the lowest operating frequency (in this case 4. 5 ohms at 3. 5 MHz) is small compared to the value of the grid resistor, the circuit will operate correctly. The grid resistor allows the grid bias developed by the cathode resistor to pass through to the grid, while providing a load for the input signal. The value of this resistor is not critical. As long as it is high enough to prevent too much loading of the source, while still allowing the grid bias through, the circuit will operate fine. The value of the cathode bias resistor is critical. Cathode current (sum of plate and screen currents) passing through this resistor causes a voltage drop across the resistor. This voltage drop is the bias applied to the grid of the tube. The bias is critical. In this amplifier the bias is chosen so that the amplifier requires the least amount of drive possible. This means making the bias as small as possible, while preventing the tube from overheating. The various currents and voltages in the tube were measured while the value of this resistor was varied. 180 ohms was finally chosen as this kept the plate dissipation safely under the maximum value of 9 watts. While the cathode bias resistor generates the tube bias, it also offers opposition to the signal that ultimately flows to the plate (the output signal). This causes negative feedback, which, in this case, is undesirable. The solution is to connect a capacitor from 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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