Those variations, (in effect an alternating signal), will be passed via the coupling capacitor to the next stage - shown by the arrow to the right. We can replace one variable resistor with another. Consider R1 to now be replaced with any one of the devices shown in this following diagram. Each can act as a variable resistor: Other connections mus
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t be made to the other electrodes of each device to bias it for correct operation so that the input signal can vary the bias which alters the internal resistance of the device, which: in turn varies the voltage at point A, which is passed on through the coupling capacitor to the next stage for further processing. The two resistors connected to the base of this transistor with the resistor in the emitter, form the biasing arrangements. These components set the level of the current flowing through the primary of the transformer - the collector current. An input audio signal is fed via a coupling capacitor to the base of the transistor. This varies the base current which in turn varies the effective resistance of the transistor and hence the collector current. The circuit below is a typical transmitter radio frequency amplifier. Here the load comprises all the components connected to the collector of the transistor Q1 - C5, L2, etc. and the antenna or whatever is connected to the output. The RF choke RFC2 feeds 12v DC to the device and prevents the RF from getting into the power supply leads. The input signal provides self-bias to the transistor. The conditions for oscillation are that the level of signal fed back is at an adequate level, and that the signal is in the correct phase to sustain oscillation. This is positive feedback. The feedback is taken by a secondary coil and inserts a signal in the base lead, changing 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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