A couple of cheap CMOS ICs are used to digitally generate audio sinewaves across a wide range in this compact battery-powered test instrument. The oscillator features both unbalanced and balanced outputs. I use signal generators of one sort or another all the time as I design and build circuits. They include a pair of simple oscillators; a transis
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tor oscillator for testing crystals, and a CMOS square wave clock source, built on a scrap of PCB. I also have a homebrewed RF signal generator which covers up to about 50 MHz in a dozen ranges, and an audio signal generator. For many years, I used a kit-built audio oscillator, a design from the now defunct Electronics Australia (EA) magazine. It used a couple of op-amps, and was stabilized with a thermistor. It worked, but it had some serious limitations. The output level would vary with frequency, and it was annoyingly microphonic. Knock it by accident, and it would make a "boinnngggg" sound over top of the wanted tone. The oscillator`s frequency also had a habit of drifting a little over time. The most critical limitation however was its power consumption. It seemed to gobble batteries! Whenever I went to use it again, the bothersome thing would require a (yet another!) new battery before I could begin to use it. Along with the one or two seconds it took to start up, a product of its thermistor stabilization scheme, I became sufficiently annoyed with it one day that I designed and built this simple CMOS-based version. The oscillator described here is now more than a dozen years old. After all that time, and some fairly heavy use, I finally replaced the original 9V battery I put in when I built it about six months ago. It draws a miserly 3mA at 9V, but it is possible to power it with any voltage from 3V to as much as 15V,...
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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