A number of simple FM devices, (without the use of a crystal) and showed how the power and frequency depends on a number of factors including the voltage of the supply and the design of the stages. The broad term given to the oscillator stage of these transmitters is `voltage dependent` as the frequency of the output is dependent on the voltage of the supply
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. We designed transmitters capable of transmitting 100 metres (the Ant), 400 metres (the Amoeba), 800 metres (the Voyager), 1km (the Ultima) and others with ranges between 100 metres and 1km. It was simply a matter of adjusting the spacing of the coil or the value of the capacitor in the oscillator circuit to shift the frequency anywhere on the band. As the battery voltage fell at the end of its life, the frequency did move slightly. Although this shift was very small, the change was noticeable in some applications, such as long-term monitoring of alarms etc. The only way to achieve this is to have an extremely stable oscillator - one that is independent of the supply voltage. Designing such a circuit is not an easy task and it has taken us quite a number of attempts to get it to work properly. At last we have come up with a suitable design and we have called it the Crystal Locked Bug - or Xtal Bug for short. During our designing we had two major problems to overcome. One was getting a low-cost crystal that would produce a frequency on the 88 -108 band and the other was getting good quality audio. When audio is fed into a crystal locked oscillator, it must "pull and push" the frequency of the oscillator - after all, that is why it is called Frequency Modulation. In other words it must pull and push the oscillator against the rigidity of the crystal and in doing so, the audio gets distorted. This is one of the major problems...
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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