The use of a quarter-wave parallel-wire line as a tuning unit has been discussed in the chapter on Short-Lines, where it was pointed out that these ` circuits ` have comparatively high Q even at the higher frequencies. Their great length ( »/4) prevents their widespread use at lower frequencies. But when the wave-length is only 1 meter or thereabo
Click here to download the full size of the above Circuit.
uts, the line has reasonable physical dimensions. And it is just in these regions that the requirement of high Q becomes difficult to attain with ordinary circuits. Our purpose now is to learn how to connect a quarter-wave line to a vacuum tube to form an efficient oscillator for the production of ultra-high frequencies. The student should now turn back to Fig. 14 E and study the parallel-fed ultraudion oscillator circuit for a few minutes. Series feed is also possible, as in (a) of Fig. 37 F. The lumped L and C of this circuit is replaced by the quarter-wave line of (b) for u. h. f. Compare (a) and (b) part by part. In general, the LC circuits used in the various types of oscillators of Chapter 14 can be replaced by quarter-wave lines. In the u. h. f. oscillator of Fig. 37 F, large copper or brass tubes may be used for the line. The lead wires to the tube are made as short as possible. The shorting bar can be shifted along the line (within limits) to change the frequency. The plate and grid leads are tapped onto the line as close to the shorted end as possible in order that, for a given voltage from the tube, the open-end voltage may be as high as possible. The effect is shown in Fig. 37 G. High voltage at the open end means strong electrostatic fields, and this means large electrostatic energy. This is similar to the action of a large flywheel in stabilizing the rotation of a machine. It results in frequency stability in...
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.....
characters left: