Generating variable audio frequencies with crystal precision is not often done because it isn`t easy to make. Low frequency quartz crystals are difficult to find, and each would only provide a singular frequency. Some small tweaking of the crystal oscillator`s frequency with a trimmer capacitor is common, but the variation is almost insignificant. Most, but real expensive oscillator designs usually produce low audio
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frequency waves with time proven, dependable, stable, adjustable Twin-T and Wien-bridge sine-wave oscillators. Many of the better ones of these use large size inductors and good quality large, high-grade capacitors. If square waves, triangle waves or pulses are needed then the sine wave is chopped up, processed and amplified as necessary. For less precise requirements some home made 555 circuit will usually do even if most of those - because of the uncertainty of the IC`s trigger point - has noticeably high jitter. This circuit is a working example that combining two frequencies produces a new useable audio product. Block diagram of this AF oscillator is depicted on Figure 1. This unique oscillator circuit uses two regular, TTL ICs and two of the most often used, low cost, color TV crystals in an unusual way. Using one quad NAND IC for both oscillators worked reliably but it had a tendency of the oscillators of locking together. That problem arises because both of the oscillators were sharing the same silicon chip, and thus they had too much coupling and influence on each other. The easiest way to prevent the lock-up is to make one oscillator out of one IC - the 7400 quad NAND gate package. Use the 7404 hex inverter for the other oscillator. The nominal quartz frequency for a color television crystal is 3, 579, 545 kHz and one is used for each oscillator. As seen on the schematics - Figure 2, the crystal oscillator...
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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