The simplest way to bias a transistor amplifier is by the fixed-bias circuit. The supply voltage is connected to the transistor`s base terminal trough the R1 current limiting resistor. The value of the bias resistor is usually selected based on the transistor`s gain from its data sheet and the selected operating collector current. Resistor R2 is t
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he load resistor for transistor Q1. The function of this R2 load resistor is to limit the collector current to safe values. The C1 and C2 coupling capacitors are used to separate the AC signals from the transistor`s DC bias current. Through these two capacitors, C1 and C2 connect the input and output AC [Alternating Current] signals. In our simple, small signal, common emitter, transistor amplifier circuit the input signal is a 1 kHz 10 mV AC voltage. Usually microphones or turntable cartridges have similarly small signal levels. Thus our simple amplifier can be used to amplify similar low-level signals. Attaching the same amplifier to the output of a crystal detector radio would result in noticeable improvement in the output audio volume. This amplifier outputs a 0. 8-Volt signal as shown by the red trace on the oscilloscope display - Figure 2. Notice that the output signal is not completely symmetrical, but the minor asymmetry does not affect the circuit operation. The scale for the blue trace is 10 mV per division and for the red trace it is 1 V per division. Since the gain of an amplifier is the ratio of the output to the input signal this amplifier stage has an AC gain of 800 mV/10 mV = 80. Since the forward transfer ratio hFE (DC Beta) or gain is different for each 2N3904 transistor, the amplifier gain may vary from below 50 to 300 or more. In spite of this respectable gain the self biased amplifier circuits largest...
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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