Tthe circuit has enjoyed popularity as a standalone booster and as a building block in larger circuits. While the circuit has its merits, we decided to further explore it to determine if it was a truly faithful solid-state version of the familiar input stage used in many tube amps. This circuit was developed by applying the well known Triode-to-JFET translation to the first stage found in a typical Fender
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tube amp, as illustrated in Fig. 2. The triode is replaced by a JFET with the following correspondence of terminals: plate to drain, grid to gate, and cathode to source. This is supported by the fact that both the vacuum triode and the JFET are voltage controlled devices which change their transconductance according to a (usually) negative control voltage. The plate resistor is changed for a variable resistor (usually a 10k to 100k trimpot) which is used to adjust the JFET`s biasing to a value close to half the supply voltage. High and Low gain inputs are often noted on the faceplate as 1 and 2, respectively. Fig. 3 shows the typical input circuit of a Fender tube amp. The key to understanding this circuit lies in the fact that the tip of each input jack is making electrical contact with the arrow-shaped terminal when no plug is inserted. When a plug is inserted, the contact with the arrow terminal is opened, thus interrupting this previous connection. As shown, the Low Gain input is in fact a resistive divider that introduces 6 dB attenuation and presents a relatively low impedance to the guitar, which is 68k + 68k = 134k, hence its "Low Gain" designation. When a low impedance source is connected to the amplifier, the grid of the valve "sees" an equivalent resistance of 68k | 68k = 34k. The High Gain input introduces no attenuation and presents a 1 Mohm impedance to the instrument. Again, a 34k equivalent resistance...
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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