how to build a metal detector
Metal detector with explanation
Praise be to God, Lord of the worlds, and thanks to God, we were able during the previous periods to develop many metal detectors with different methods, and what helped us in that is the participation of some of the devices in the basic transmitter circuit, so it was easy to modify and replace, and what we had to do was diversify by making and creating receiver circuits and amplifying the sound, and from here We had this stand.
We wanted to clarify here basic concepts in some of the devices, and they had a lot of questions from the followers of the Make a Metal Detector channel, and therefore, in order to meet the desire of many requests, we must explain and clarify the mechanism of making the metal detector and overcome the alternatives to parts for the devices if the parts are not available, and accordingly, please attach The transmitter circuit that we used with some devices and it was unified in it, and in order to be together in the explanation, let us first attach to you a picture of the unified transmitter circuit first and how we were able to extract the signal and hear it in more than one way, especially since we will now talk about a metal detector circuit that distinguishes between iron and other metals and its depth is considered Very good depth:
When we see the previous circuit, we know that we use the oscillator (transistor) for transmission. This circuit is based on making two signals of equal frequency. The first transmitter, which consists of an npn transistor, two capacitors, and a file only, transmits a frequency close to (100) kilohertz, and on the second oscillator, which also consists of an npn transistor. And only two capacitors and a coil to transmit a frequency close to (100) kilohertz, taking into account that one of the two coils must be large and close to the ground, and the second coil is small in size and is placed in the control box so that we can control through it the amount of the output frequency.
In order for the circuit to distinguish minerals clearly, the two points y and x must be connected together through a resistance of 2 kilo ohms. But my dear brothers, there are important matters that we will take into account, God willing, in the following paragraphs of the topic, so follow us to the end.
After we have clarified the mechanism of the transmitter, which is in the previous picture, we proceed to the first circuit to enlarge the signal that we can use, which is to enlarge the transistors. Through a total of 4 transistors, we can enlarge the signal to be very clear and to be honest, and because I used all the methods that we will talk about, God willing, I say that the method Transistors are the best method in terms of signal amplification and clarity. This method begins with the synthesizer transistor, which unites the two signals that came out of the first circuit (the transmitter circuit), and then it is delivered to a group of transistors that amplify the signal to be clear on the device’s headphone, as in the following picture:
The previous circuit is the best circuit for me, as it deals with a group of transistors and resistors that you can control by changing the values of the capacitors and finding the appropriate resistors for your work to get a very clear frequency, but also we must note the following notes before sailing in the rest of the signal amplification circuits until we get a real device that we can Using it in the field we are assured:
First: The work of the device in the field depends on how to achieve stability in the outgoing frequency and thus obtain a metal detector similar to the devices that are purchased for thousands of dinars. This stability can be obtained from the topic in the link below:
stability of the metal detector
Second: The types of transistors used are of the npn type, and the types that were personally tested by me are 2n3904, bc547, bc548, bc549, 2n5551, bc550, c1815, taking into account that if we use one type and then use another type in the same circuit, this does not
affect the operation of the device.
Third: The types of capacitors used, as we used here only two types of capacitors, which are a 220uf polar capacitor, and it can be replaced by any capacitor close to this capacitor.
Fourth: The files used, their sizes and the number of their rolls, and here I am attaching a topic specialized in this matter:
Now it remains to say that we can enlarge the signal coming out of the transmitter circuit also according to the 555 timer circuit and also through one transistor circuit only according to the equalizer circuit, but before that we use the transistor synthesizer transmitter circuit in order to get the required frequency, which is the difference between the frequency of the coil on the ground and the coil that In the control box, here we see the signal coming from the synthesizer transistor to the ic555 as in the following picture:
We should note here that we used an additional capacitor between pin 3 of the AISI 555 and the headphone terminal, which is a polar capacitor with a value of (10uf) with a power of 25 volts.
Finally, we reached the last amplification circuit that was tried by me, which is an amplification circuit with one transistor following the Equalizer circuit. Through this transistor, we can hear the signal of the metal detector, and with the same thing as in the previous timer circuit, we need a synthesizer transistor to output the signal, then amplify it with the fourth transistor. Suitable replacement for ic555:
Please watch the video of the experiment in the اصنع كاشف معادن channel
To this point, we hope from God Almighty that we have succeeded in delivering the information to the fullest extent, and we hope that you will follow us on the channel.
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