I am continuing to add DIY equipment to my home workshop. Audio oscillator is a very useful tool that is needed when we test audio projects. I already have a similar tool but it is just an oscillator without a frequency counter. I decided to use the schematic described in this page:. BTW, I have a deep respect for the owner of this site - there
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are tons of useful schematics, very well described and to this moment all projects which I have built from there work flawlessly. Anyway, back to my project. The original schematic has only sinusoidal output, but I wanted a square wave output also. This was achieved by utilizing forth opamp from TL084 IC and adding a couple of schmitt triggers to make a square wave signal. Audio frequencies are divided in three overlapping ranges: 18Hz - 230Hz, 180Hz - 2300Hz, 1800Hz - 23000Hz, which are switched with a rotary switch. Capacitors of Wien Bridge are soldered directly on that rotary switch. I made it with an enclosure from an old large capacitor. Inside are photoresistor and standard 5mm red LED. Outside is wrapped with a black tape to isolate from ambient light. The frequency counter was a challenge: there are many schematics on the web, but majority of them uses a microcontroller and I don`t have a PIC programmer yet. Finally I discovered a relatively simple circuit here:. Later I found almost the same circuit on this address:. The first has some errors, which I found too late and had to correct already etched PCB with some wires :) The schematic uses crystal to oscillate at 4. 194304 MHz and this frequency is then divided down to 1Hz, which is 1 second period. During this period input signal is counted and the result is displayed on six 7-segment LED indicators. The accuracy of the counter depends on the accuracy of 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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