Quasar is a selective IB metal detector with metal recognition and direct signal processing. The VDI scale in Quasar is divided into 16 columns, with the ability to remove any of the columns from the search (Closing them with a mask) as well as audio multi-tone indication. In the latest firmware versions, the Quasar's operating frequency can be up to 17 kHz and depends on the search coil.
The Quasar metal detector circuit has an average level of complexity (The only component in short supply is the MCP3201, so there is already a metal detector circuitand Quasar AVR where, thanks to replacing the microcontroller, this problem was also eliminated). But the presence of a programmable microcontroller and coil for Quasar, as for any other selective metal detectors, creates some difficulties for radio amateurs. The manufacture of Quasar is carried out by people with experience in the manufacture of metal detectors. In general, the Quasar metal detector has medium difficulty level for making it yourself.
Download the Quasar metal detector diagram in pdf format —
The presence of an accessible screen makes the Quasar a very convenient and easily repeatable metal detector with metal recognition.
Working screen of the metal detectorQUASAR as follows:
Metal detector discrimination scaleQUASAR divided as follows:
The KVASAR metal detector is controlled by 6 buttons:
Firmware for the Quasar metal detector Version 1.4.5 (the latest firmware version for today) –
For flashing the microcontroller of the Quasar metal detector, programming fuses must be arranged as follows:
The developer of the Quasar metal detector gives a brief description of the search coil he made. Coil type DD with outer diameter 230 mm. TX – 40-45 turns with 0.5 mm wire and RX – 200 turns with 0.2 mm wire. The TX winding is connected to a metal detector with serial resonance, the capacitance of the capacitor is 0.3 mF, the resonant frequency is 8.192 kHz, the RX winding is connected to a metal detector with parallel resonance, and is adjusted to a frequency 1.5 - 2 kHz below the TX resonant frequency.
Below is diagram for connecting such a coil to the Quasar metal detector
Description of launching and setting up the KVASAR metal detector with oscillograms -
Description of the menu and settings in the Quasar metal detector -
Conclusion: The QUASAR metal detector has a simple circuit and inexpensive components (microcontroller, screen, etc.), which makes it very attractive for self-production. In operation, Quasar shows quite pleasant characteristics and good results, and can easily compete with entry-level branded metal detectors.
The metal detector project received its continuation in versions and QUASARAVR, Therefore, it’s worth starting to manufacture these particular versions of the metal detector, since the author has stopped releasing firmware updates for QUASAR!
When writing, materials were used from the author’s website - http://fandy.ucoz.org/
All questions about the Quasar metal detector can be asked in the comments to this article. And also write your review, wishes and suggestions for adding to this material.
Metal detector Quasar AVR is selective equipment with the ability to recognize metals. Signal processing is direct. In the unit, the VDI scale consists of 16 columns and it is possible to remove any of the metals from the search. The Quasar Avr has a multi-tone sound indicator. The latest modifications of the equipment have an operating frequency of up to 17 kHz. This indicator depends on the search coil.
You can make a Quasar Avr metal detector with your own hands - the level of complexity of the circuit is average. The Quasar coil and programmable microcontroller create certain problems for radio amateurs. This type of metal detector can be manufactured by people who have experience in developing similar devices. It will be difficult for beginners to make the board and coils on their own.
The metal detector is equipped with a display, thanks to which you can quickly recognize metal.
The DD type coil must have a diameter of 230 millimeters. The number of turns of the external winding should consist of 40-45 turns, the diameter of the wire should be 0.5 millimeters. The internal winding should consist of 200 turns of wire with a diagonal of 0.2 millimeters.
The external winding should be connected to a metal detector with series resonance, the condensate capacitance should be 0.3 mF. Connecting the internal winding to a device with parallel resonance.
It’s not difficult to create a Quasar Avr metal detector with your own hands if you stick to the basic diagram.
Metal detector Quasar AVR has the following characteristics:
The volume level can be adjusted within 0-7 units. For this purpose, you must use the buttons from the Left (decrease) and Right (increase) menus;
The response threshold value is 1-30. Adjustment is made using the Up (increase) and Down (decrease) buttons located on the screen;
There is a ground balance. To enable this mode, press the OK button in the main menu of the screen. For the readings to be correct, it is necessary to turn on the mode when the sensor is raised above the ground. Raising and lowering it will allow you to achieve the smallest response deviation from the ground. To save the results, you must click OK. If you exit the menu using the Esc key, the changes will not be saved;
·mask – with its help you can close sectors that do not arouse interest;
The screen is backlit. It is always on the menu. The Left and Right keys in the main menu allow you to turn the backlight on/off;
·you can adjust the backlight level. The Left and Right buttons increase or decrease its brightness;
·change volume in the range 1-32. In order to increase or decrease the sound, you must use the Left and Right keys;
· sound delay – when metal is detected, the signal disappears for several seconds;
· ferrite calibration. The Up or Down buttons allow you to switch the ferrite calibration to automatic mode. A small piece of ferrite must be passed over the coil several times, but not close to the sensor. The obtained deviation results can be saved by clicking on the OK button;
·sensor balance – allows you to control the level of imbalance during operation;
·You can adjust the transmission frequency. This function allows you to set the frequency of the external coil and tune its circuit to resonance.
Configuring the Quasar AVR metal detector is carried out as follows:
1.It is necessary to supply power without connecting sensors. Initially, the operation of the controller is checked. If the LED constantly blinks, this indicates that the Quasar AVR metal detector circuit is connected incorrectly. If the display is working properly, an error message will appear on it. If the controller is output correctly, the LED blinks 1-2 times and loading continues;
2.Using a trim resistor, you need to set the best image quality;
3. The frequency of the external coil is manually adjusted to the resonant frequency of the sensor;
4. record deviations during ferrite calibration.
One day I had a chance to start assembling a Quasar. I’ll skip assembling the block, because... There’s nothing complicated there, I’ll stick with the reel. According to the Author's recommendations, a DD sensor was used with the following parameters: outer diameter 230 mm, in the transmitting coil TX - 40-45 turns of 0.5 mm wire, RX - 200 turns of 0.2 mm wire. The TX circuit is connected according to a circuit with a series resonance, the approximate capacitance is 0.3 uF. It was tuned to a frequency of 8.5 kHz, but in general the device can operate at a frequency of 4.5 - 9 kHz. The RX circuit is connected according to a parallel resonance circuit, and is tuned to a frequency 1.5 - 2 kHz below the TX resonant frequency.
Subtleties:
We wind the second coil in the opposite direction relative to the first (the current of the DD coil should flow in one direction), since we wind the coil on the same template, the second coil will turn out to be inverted and the current will flow in the opposite direction.
To obtain a minimum voltage in the future (after filling with epoxy, the coil will be slightly unbalanced), when winding the last turns of the transmitter coil, wind them with a margin so that you get a loop at the bottom of the “tuning turns” coils, and do not fill them. Now that everything is filled with resin, move this loop in different directions until you achieve the minimum voltage on the receiver coil, then you can finish pouring.
The coils were wound on mandrels and soaked in “88” glue. Coil stiffness
after drying, it is such that they can be bent to obtain the desired configuration.
The terminal of the receiving circuit that is closest to Cx (i.e., the internal terminal) should sit on ground. This nuance affects the quality of the balance.
If the detuning of the ground and ferrite is in the minus, re-solder the ends in places in the PX and everything will go to +.
When adjusting from the ground, the value should not be more than +80, roughly speaking it should be from 0 to +35, the adjustment from the ground affects the sensitivity. The less interference, the weaker the intuition.
If with foil, then shield only the RX (lower receiving) coil. TX - may not be shielded. If you shield both, then only through the insulation between them. If you cover
graphite, then completely without any gaps.
The sealed lead-in must be located in the TX field, the coil leads must not pass through Cx (the center is the intersection of the coils)
The auto balance button must be pressed with the sensor raised, and then lowered and raised.
For 5 kopecks of the USSR in black soil with a 25cm DD coil there should be a sensitivity of at least 25cm with clear discrimination. VDI can jump at 30cm, about 1-2 sectors with a figure of 3 segments (but there should be no gaps between segments, such gaps will exist if the target is made of black metal) and there should be a high sound signal on both sides of the swing, so you need to choose what to trust more: VDI or audio signal. In Quasar everything depends on the coil parameters...
And so, in the article we’ll talk a little about the Quasar Avr metal detector, look into history, analyze the characteristics and consider all aspects related to its creation.
Quasar AVR metal detector - this device is based on the principle of inductive balance, or, in simple terms, IB. Selective and has VDI, 16 discrimination sectors, each can be closed. All spare parts, according to the author, are available. Direct signal processing.
Quasar technical characteristics:
Overall, this is a fairly complex metal detector to assemble. It’s definitely not suitable for beginners; there’s a lot of hassle with both the board and the coil. But if you are a more or less experienced fighter, then reserve your strength and move forward.
In principle, there is nothing to say about the diagram; you need to look and figure it out yourself, all on your own and with your own hands. Here is a picture of it and below is a link to it.
Now let's talk about how to make a coil for a quasar. For a quasar, a DD sensor is used, which has the following parameters:
The connection diagram itself looks like this:
As you can see, TX is connected according to a circuit with a series resonance, and RX is connected with a parallel one. TX is adjusted to a frequency from 4.5 to 9 kHz, in RX to a lower frequency - from 1.5 to 2 kHz.
Let's talk a little about the settings of this device, what operational settings it has. This means that the Quasar Avr metal detector has the following settings:
We've finished setting up the quasar arm, now let's talk about the firmware.
In principle, there’s not even anything to tell here, download the latest version on the author’s website or from us, and flash it. Here are images of how the fuses should be.
In general, the Quasar metal detector has received very good reviews. One of the most popular homemade devices, in many respects it can be compared with mid- and high-level industrial metal detectors. An excellent device that competes with many devices. Its subsequent versions are further developed. Beginners should think about it, because a quasar is cheaper, even if you order from someone else, than the same ICQ 150 or 250, and its characteristics are many times better. So think, decide. But if you decide to buy, the main thing is to find a good seller and manufacturer, so as not to suffer and swear at the device later. A lot depends on the manufacturer and build quality. Look for reviews.
And finally, a little video of a cop working with a Quasar metal detector.
