This project is an extension of Metal Detector MkI, and shows how metal objects are detected. It is the second in a series of circuits and allows a great deal of experimentation, especially if you have a CRO (Cathode Ray Oscilloscope) and a few items to detect. You can view the waveforms and see exactly how they alter as an object is brought into
Click here to download the full size of the above Circuit.
the field of the coil. Metal detectors will detect ferrous (iron, steel, stainless steel) as well as non-ferrous (copper, tin, gold, lead, silver, aluminium) as well as alloys (brass, cupro-nickel, pewter etc). Depending on the complexity of the circuit, a metal detector will be able to discriminate between a lump of gold and an aluminium ring-pull from a drink-can. The circuit we have presented in this project is very simple and works on the principle of detecting the amplitude of a waveform. This is called AMPLITUDE MODULATION. When a metal object is placed inside the detecting coil, some of the magnetic flux passes into the object and creates a current called an eddy-current. This "uses-up" some of the magnetic flux and thus less flux is available for the receiving coil. This produces a lower output from the coil and causes the second transistor in the circuit to be turned OFF slightly and the voltage on the collector rises. This allows the third and fourth transistors to oscillate and pass a signal to the fifth transistor to drive a mini speaker. As you can see, the circuit consists of a number of BUILDING BLOCKS. All you have to do is understand how each block works and you will understand the whole circuit. The concepts of TALKING ELECTRONICS is to explain how various building blocks operate so you can design your own projects. You can take any of the blocks and add them to your own project, but it will be necessary...
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: