A simple metal detector on germanium transistors. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / metal detectors
Comments on the article
Schematic diagram
A diagram of a simple transistor metal detector is shown in fig. 2.5, a. It consists of a high frequency generator and a receiver that registers changes in the frequency of the generator when metal objects approach it.
Rice. 2.5. A simple transistor metal detector: a - circuit diagram; b - design of the coil L2; c - printed circuit board drawing
Receiver metal detector heterodyne type. It is made on just one transistor V2, and combines the functions of a local oscillator and a detector.
The local oscillator is assembled according to the capacitive three-point scheme. The advantage of such a circuit is the use of an inductor without taps, which is very convenient for beginner radio amateurs.
The oscillatory circuit contains an inductor L2 and a capacitance made up of series-connected capacitors C4-Cb. The frequency of the local oscillator can be changed with a tuned coil core L2.
The high frequency generator is assembled on the transistor V1 also according to the capacitive three-point circuit. The frequency of the generator depends on the inductance of the coil L1, which is made in the form of a frame. If a metal object is near the coil, its inductance will change. This will lead to a change in the frequency of the generator, which will be immediately registered by the receiver. If, for example, the generator is initially set to a frequency of 465 kHz, and the local oscillator of the receiver is set to a frequency of 465,5 kHz, then a signal with a frequency of 500 Hz will be heard in the phones. When the coil L1 approaches the metal, the tone of the signal in the phones will change. This will serve as a signal for the detection of a metal object.
Element base
In addition to the transistors indicated in the diagram, germanium transistors of the P401, P402 series can be used.
Phones - TON-1 or TON-2. Moreover, both capsules must be connected in parallel so that the total resistance of the phones is 800-1200 ohms.
All resistors can be MLT-0,125 or MLT-0,25, capacitors - KLS-1 or BM-2, power switch - single-pole toggle switch.
Battery - three cells 316, 343 connected in series.
Coils
Coil L1 is a rectangular frame measuring 175 x 230 mm from 32 turns of PEV-2 0,35 wire.
The design of the L2 coil is shown in fig. 2.5, b. In two paper cylindrical frames, segments of a rod with a diameter of 7 mm made of ferrite 400NN or 600NN are placed:
- the first frame 20-22 mm long, fixed permanently;
- the second frame is 35-40 mm long, movable, for adjusting the coil. The frames are wrapped with paper tape, on top of which a coil is wound - 55 turns of PELSHO 0,2 wire (you can PEV-1 or PEV-2), the coil leads are fixed with glue.
Printed circuit board
The printed circuit board is shown in fig. 2.5, c. The board must be connected to the coils, battery, switch and connector X1 with a flexible stranded wire in isolation.
The L2 coil must be installed at a distance of 5-7 mm from the turns of the L7 coil.
Block X1 and the switch are recommended to be attached from the outside to the side wall of the case. A wooden handle about a meter long can be glued to the top of the case.
Author: Vasiliev V.
See other articles Section metal detectors.
Read and write useful comments on this article.
<< Back
Latest news of science and technology, new electronics:
Artificial leather for touch emulation
15.04.2024
In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>
Petgugu Global cat litter
15.04.2024
Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>
The attractiveness of caring men
14.04.2024
The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>
| Random news from the Archive The benefits of sleeping during work hours
16.08.2002
A study on sleep during working hours was carried out by physiologists from Harvard University.
A group of 30 volunteers were asked four times a day - at 9 am, at noon, at 4 and 7 pm - to find an inconspicuous detail in a drawing on a computer screen, the position of which changed each time. Ten test subjects did not sleep all day, and by the evening the detection of the desired part had slowed down by 52 percent. The other ten were allowed to sleep for half an hour at two in the afternoon. Their reaction time did not increase in the evening. Ten more slept in the middle of the day for an hour - their results improved by the evening.
A dozen more volunteers were invited, they were not allowed to sleep, but simply to rest. It did nothing to increase their vigilance. Scientists have found a theoretical explanation for such results. Our ancestors, primates, inhabitants of hot tropical countries, are mainly crepuscular animals, they are especially active at dusk, in the evening and in the early morning. And in the middle of the day, at the hottest time, they sleep under the canopy of dense crowns.
So, demand from your superiors to start a dormitory at work and increase the lunch break by an hour.
|
Other interesting news:
▪ Biometric authentication for PC
▪ Smart soft material
▪ An easy way to extend life
▪ Greenhouse effect - in greenhouses
▪ Mosquito trap
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ Modeling section of the site. Selection of articles
▪ article by Albert Einstein. Famous aphorisms
▪ article Which village is the birthplace of two marshals and twelve generals? Detailed answer
▪ article Operation and repair of intershop and shop oxygen pipelines. Standard instruction on labor protection
▪ article How to make a computer quiet. Encyclopedia of radio electronics and electrical engineering
▪ article Advanced switching power supply in a matchbox, 9 volts 1,1 amperes. Encyclopedia of radio electronics and electrical engineering
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese