Reviews of the Quasar Arm metal detector. Reviews of the Quasar Arm metal detector Quasar Avr circuit in a deep case

A metal detector is a means of finding car keys lost in the garden or sewer hatches under the leaves during autumn :)

This metal detector is called Quasar (Quasar), it was developed by Andrei Fedorov, but not without the help of members of the md4u.ru forum, who gave advice and reported errors during testing of new versions of the software.

Quasar is a metal detector with direct processing, working on the principle of induction balance. The main advantages of such metal detectors are the ability to detune from the ground, as well as the difference between metals in their resistance and ferromagnetic properties.

This metal detector can determine what metal lies underground, although not with 100% probability, but it can easily determine non-ferrous metals from ferrous ones, and in most cases which non-ferrous metal is located under its coil.

It can notify the owner about metal underground using sounds of different tonality (frequency), and display information on a sixteen-character two-row display in the form of a histogram. It has a bunch of settings, but first things first.
Be careful, there are a bit more pictures below.

In the current implementation we have:

  • Automatic ground tuning
  • Automatic resonance tuning and manual mode
  • Volume adjustment
  • Adjusting display brightness
  • Pinpointer mode
  • Setting the low supply voltage limit for auto shutdown
  • Ferrite calibration with the possibility of adjustment
  • Ability to select voiced targets (mask)
    • Several sound schemes for voice acting
    • Scheme 1: Frequency varies smoothly depending on the VDI target throughout the entire range
    • Scheme 2: Frequency varies smoothly depending on VDI from 0 (90) to 41 (131) degrees. Targets below 0 are sounded in a low tone, above 41 - in a high tone
    • Scheme 3: Targets below 0 (90) are sounded in a low tone, above 0 (90) - in a high tone
  • Three coarse gain levels
  • 30 smooth gain levels
  • Soil filter
  • View coil balance in real time

The circuit is not complicated, there are no particularly scarce parts. You can download it

Let's start with the barbell. It remains with a simpler implementation of the "Volksturm sm+geb" metal detector. It was made from PVC pipes with adapters at 45 degrees. Before gluing, this design looked something like this:

After gluing we have a working stick:

The reel seat was made using plastic bolted connections, used in the same plumbing fixtures, which is then attached to the reel using epoxy glue and can be detached from the rod:

We made the armrest from the photodrum of a large A3 format copier :) That is, we attach a little grinder, a drill, to a rod and it turns out that the whole structure held up pretty well.

We wrap the handle with something soft, then close it with a large-diameter heat-shrink tube, warm it up, and you get a comfortable, ergonomic handle :)

We're almost done with the mechanics, we'll paint it later. We will not talk in detail about how the board was made; we will only dwell on the essential points. The Cradex Z5 case with dimensions 103*90*40 fits perfectly under the printed circuit board developed by one of the forum participants for microcircuits in DIP packages. Link to the board at the end of the article.

We buy parts, measure how suitable the board design is, and take electric capacitors from the low-ESR series.

Textolite was etched in ammonium persulfate. Poison quickly and beautifully. Just fill it with warm water, about 80 degrees.

Afterwards the display is soldered and turned on for the first time - testing.

If one line of dark rectangles is visible on the screen after power is applied, the screen is working and this is its self-test mode - when power is applied, but control commands have not yet been received (there has been no initialization).

You won't see some components on the board from the parts side, because... I couldn't find them in the DIP form factor. This is an adjustable zener diode TL431, a pair of filter capacitors and not beautiful wires in the area of ​​the operational amplifier, because We couldn’t find the original one, we took a similar one, but it had a slightly different pinout - we had to be tricky :)

Let's start working with the body. You need to make several holes in it - for the screen, control buttons, coil connector and power connector. The case must also be insulated from moisture - otherwise the device may begin to malfunction or fail. For the convenience of cutting a hole for the screen, we took a screen with the same functionality, only with a blue filter, since our green one was already soldered to the board with a permanent connection.

It stood up perfectly, but :) When we tried to try it on for our screen, disappointment knew no bounds :) They turned out to have different sizes. I had to finish it.

In the end, everything worked out. Tried it on, connected it, it works :)

The upper front panel was recessed flush with the plastic so that it did not protrude, because then it was planned to cover it all with film and a sticker. The screen itself was secured with a large amount of hot-melt adhesive. This type of connection has two advantages: water will not get inside and there are no bolted connections, which would then still have to be sealed.

They poured it with a regular heat gun, and where it didn’t warm up well, they helped with a hairdryer from a soldering station. At this moment, the screen itself may change color to bluish or some other color due to heating; the main thing here is not to overdo it. After cooling, the color returns to normal and everything works normally.

We made the board for the buttons ourselves, because... there was no suitable ready-made one for this building. There will be a file at the end of the article. The diodes in it are smd.

And so, all the holes are made, the button board, speaker, power connectors and coil connections are also sealed with hot-melt adhesive.

Regarding the design, we thought for a long time about what color to choose. We chose the black option.

The technology is simple. We print the picture and cut out a hole for the screen. They cut with a scalpel. Next, we glue the film under the screen of the design, then take a transparent, matte, self-adhesive film and glue the resulting pie onto the plastic, cut out the excess film and you’re done!

The block was attached to the rod using a piece of thick plexiglass, cut into strips and bent under the influence of local heating, screwed on one side to the box, the other to the “pipe holders” or whatever this crap is called...

By the way, later the two outer fastenings were removed, that is, the whole thing held up perfectly even on two fastenings.
So, after carrying out all these operations, we painted the bar and this is what came out:

Separately, it remains to talk about the coil. We can say that this is the most sensitive element and it must be assembled so that when searching for and touching all kinds of grass and other objects, it does not “microphone” and reacts only to the phase change caused by the metal under the sensor. We immediately wanted to make the coil as it should be, we wound the coils... By the way, all the wires were taken from an old CRT monitor. Its demagnetization loop fit perfectly under the transmitting TX coil, a thinner wire was found in another coil, the wire to the metal detector unit was taken from its non-detachable VGA cable, in general there were enough wires from there :)

After two coils have been wound, one of them (receiving, RX) must be wound into a screen made of foil or graphite. If it is foil, then it is necessary to make sure that there is no short-circuited turn from this screen; if it is graphite, then it is necessary that the resistance from the center to the edges of the coil is approximately 1 kOhm.

After selecting a resonant capacitor (the device, of course, adjusts itself, but we selected the frequency closer to 9 kHz), it was time to fill these coils in a mold with epoxy resin. And then a dispute broke out with the box and the Internet. The box says to dilute in a ratio of 1:5. One in five, damn it! Considering that we already had some experience working with epoxy, where the ratio of 10-12:100 was mentioned everywhere, some misunderstanding arose. But they decided to do as written, the manufacturer won’t write garbage on the box :) And they didn’t even decide to test it with a small volume of this resin. I want to go to the cops as soon as possible! In short, they started pouring it, then they changed their minds, because the proportions of resin and hardener were just right for 10-12:100, and then they forgot how much of what they had already poured... In general, they ruined the solution, but they tried to fill it in :)

And it didn’t even think about freezing. What to do? We took the coils out of the mold, cleaned them of all the resin, and another idea came to mind. After all, our CRT monitor is a kind of cornucopia for building a metal detector :) The stand from it was also useful. We take it, remove everything unnecessary, attach the coils, fill in epoxy in normal proportions, drill holes - ready!

All this showed its efficiency already in the first mine on the Sozh River:

As for the power supply of the metal detector - at the moment it comes from a regular 12 V lead battery, which you carry with you in your briefcase, but there is little buzz from this method. There are immediate plans to build a power supply on one 18650 element (about 2Ah at 3.7 V), make an indication of the charge level, charge from USB and a 3.7-7 converter, because It is from this voltage that the metal detector is powered. It would be possible to go up to 5 Volts, bypassing the stabilizer for the controller and ADC, but it is better to swing the coil at a higher voltage, then the sensitivity will be higher, but more on that in another article. It consumes about 100 mA at 7 V, so from one 18650 battery you can count on approximately 10 hours of operation. And the main thing is that this thing will be much lighter than a lead battery, which will allow it to be mounted together with the block on a rod.

The promised boards in lay format for the Quasar metal detector, as in this article.

All the best!

DIY metal detector Quasar ARM

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.

Quasar has buttons that allow you to control the device:

1. “Up / Barrier + / Autotune”;
2.Enter / OK / Ground balance" ;
3.“Right (+) / PinPointer”;
4.“Left (-) / Backlight”;
5."Menu/Esc";
6."Down/Barrier-/Autotune".



Creation of the Quasar AVR coil

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.

Quasar AVR diagram






All components are freely available and their prices are low. The operating characteristics of the device are quite good and it will compete with branded entry-level metal detectors.

List of parts for Quasar workstation


Setting up Quasar AVR

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.

For better performance, you need to perform the following manipulations:

  • R29 - select the resistor resistance so that the voltage value on the indicator is equal to the voltage on the battery;
  • R9 - select a value so that the current consumption of the output stage of the device is equal to the true value. We measure the voltage drop across this resistance, then measure the current readings in the Quasar menu, and calculate the resistance of this resistor using Ohm’s law.
  • R3 - by adjusting this resistance one of the important settings is made - the quality factor of the TX circuit. The recommended value is 5...6. Using a donkey, we measure the peak-to-peak voltage swing (Vpp) of capacitor C6 (I strongly recommend installing a jumper on the board, and the capacitor itself in the sensor). Next, you need to divide the resulting value by 5 (the swing voltage). By selecting a resistor we make the result 5...6. If the quality factor is underestimated, we will not be able to achieve maximum sensitivity. If the quality factor is too high, the sensitivity will be too high and, as a consequence, problems with discrimination and false positives
  • R7 - by selecting this resistor, the gain of the input stage of the metal detector is adjusted. For inexperienced radio amateurs I recommend achieving 50, and for professional ones - 100 higher.

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.

Technical characteristics of the quasar:

  • Discrimination - yes, 16 sectors.
  • Selectivity is present.
  • Multi-tonality is present.
  • Operating frequency – up to 17 kHz (depending on the firmware and coil).

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.

Quasar metal detector circuit

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.

Quasar avr coil

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:

  • TX - approximately 40 or 45 turns of 0.5 mm wire.
  • RX – wire 0.2 mm, number of turns – 200.

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.

Setting up a Quasar metal detector

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:

  • Volume control – from 0 to 7 units.
  • The response threshold is the inverse value of sensitivity; it takes values ​​from 1 to 30.
  • Ground balance.
  • Mask – covers sectors that are not of interest to us.
  • Display backlight - on and off.
  • Backlight level – well, everything is clear here.
  • Gain – rough gain of the path, one step of 2 times.
  • Volume change – varies the volume depending on weak responses, range from 1 to 32.
  • Sound delay - everything is clear here, the delay in the appearance of a signal after detecting a target.
  • Ignoring pulses is also a tool against interference; it blocks those pulses that are short in duration.
  • Ferrite calibration.
  • Sensor balance.
  • Transmission frequency – allows you to adjust the transmission frequency.

We've finished setting up the quasar arm, now let's talk about the firmware.

Quasar metal detector firmware

In principle, there’s not even anything to tell here, download the latest version on the author’s website or ours, and flash it. Here are images of how fuses should look like.

Quasar metal detector reviews

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.

"Kvazar" is an IB metal detector with direct processing, developed on an affordable element base. A selective mode has been implemented with VDI display as a bar chart (signograph), and the ability to mask each of the 16 sectors. Sound indication - multi-tone. Ground response suppression is vectorial.

Forum with discussion of the device: http://md4u.ru/viewforum.php?f=95

General view of the layout

Device screen

VDI scale in degrees

Purpose of the buttons:
  • SW1"Up / Barrier+ / Autotune"
  • SW2"Enter / OK / Ground balance"
  • SW3"Right (+) / PinPointer"
  • SW4"Left (-) / Backlight"
  • SW5"Menu/Esc"
  • SW6"Down/Barrier-/Autotune"
  • Added menu "Processing"(as in the ARM version).
  • Minor adjustments.
  • A critical error in the algorithm for auto-adjusting the ground response angle has been fixed.

Firmware version 1.4.3

  • The algorithm has been adjusted.
  • Pinpointer adjusted.

Firmware version 1.4.2

  • The processing algorithm has been adjusted.
  • Signograph drawing has been adjusted.
  • Pinpointer rewritten.
  • The sensor balancing screen has been changed.
  • The operation of automatic ground balance has been adjusted.
  • Minor fixes.
  • Increased target reaction speed.
  • Minor adjustments.
  • Algorithm correction.
  • Another algorithm correction.
  • The target recognition algorithm has been changed.
  • Added threshold tone.
  • Processing has been adjusted.
  • Minor adjustments.
  • The sound has been rewritten.
  • Improved selection.
  • Minor adjustments.
  • Added minimum battery voltage level.
  • Auxiliary algorithms have been adjusted.
  • Cosmetic improvements.
  • Corrected pinpointer operation
  • Minor changes made
  • Automatic frequency selection has been adjusted.
  • Bugs fixed.
  • Intermediate option.
  • The principle of sound formation has been changed. "Sound" discrimination has become better.
  • The "Sound Delay" and "Ignore Pulses" options have been removed.
  • Bugs fixed.
  • Echo suppression has been adjusted.
  • Reduced sound frequency in pinpointer mode.
  • The pinpointer has been added. The volume can now be adjusted using SW4(in a circle), and the pinpointer mode is entered by pressing SW3. The pinpointer mode is exited by pressing any button.
  • The algorithm for suppressing ground response has been changed.
  • Minor adjustments.
  • The voice acting for ground balancing has been adjusted.
  • The search algorithm for the TX resonant frequency has been changed.
  • Reduced response time of buttons.
  • Improved VDI scale rendering.
  • The process of detuning from the ground has been announced.
  • Minor adjustments.
  • Sound delay is now adjustable.

Firmware version 1.1.9 .

  • The operating mode of the response level indicator can be selected - static or dynamic (menu item "Level indicator").
  • Added suppressor of short sounds (clicks). By default it is disabled, enabled from the menu "Audio -> Ignore pulse". The higher the number, the stronger the clicks (and the greater the chance of missing a small target).
  • The menu has been slightly redesigned.

Firmware version 1.1.8 .

  • The response level indicator is made dynamic again, but more clear.
  • The sound has been slightly improved.

Firmware version 1.1.7 .

  • Target responses that fall under the mask are drawn on top of the mask.

Firmware version 1.1.6 .

  • The VDI scale has been slowed down.
  • Echoes after overload are largely suppressed.
  • Fixed sensor imbalance measurement error.

Firmware version 1.1.5.

  • Input filters have been replaced.
  • The sensitivity has been slightly increased.
  • 3 gain levels left (GAIN).
  • Overload signal corrected.

Version 1.1.4 .

  • The maximum audio frequency is finally truly reduced.
  • Echo suppressed.
  • An input overload signal has been introduced (~100 Hz).

Version 1.1.3 .

  • The NORMAL filter is made the default filter.
  • Identified errors have been corrected.

Version 1.1.2 .

  • Removed filter #1. When you turn it on for the first time, the filter is set to HARD; if necessary, switch to NORMAL.
  • Reduced maximum audio frequency for better listening experience.
  • The reaction time for pressing buttons has been slightly reduced.
  • A number of minor bugs have been fixed.

Version 1.1.1 .

  • An error that appears when switching gain has been corrected.

Version 1.1.0 .

  • The principle of target voicing has been changed (the long response has been replaced with a short one).
  • The "Sound delay" menu item has been removed as unnecessary.
  • The response level indicator is made static.
  • The ground response angle is remembered.
  • The backlight is now also turned on during "Volume" and "Barrier" adjustments.
  • Minor bugs fixed.

Version 1.0.8 .

  • Added switching of the cutoff frequency of the ground filter. Now:
    Filter 1: Light soil filter.
    Filter 2: The usual middle filter, which was in previous firmware versions.
    Filter 3: Filter for heavy soil.

Version 1.0.7 .

  • Two more have been added to the existing voiceover scheme. Now:
    Scheme 1: The frequency varies smoothly depending on the VDI target throughout the entire range.
    Scheme 2: Frequency varies smoothly depending on VDI from 0 (90) to 41 (131) degrees. Targets below 0 are sounded in a low tone, above 41 - in a high tone.
    Scheme 3: Targets below 0 (90) are sounded in a low tone, above 0 (90) - in a high tone.

fuses settings for PonyProg:

fuses settings for SinaProg:

A DD sensor with the following parameters was used: outer diameter 230 mm, 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, in the prototype it was tuned to a frequency of 8.192 kHz, 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.

It should be especially emphasized that the quality of the Quasar ARM metal detector (I prefer the Latin spelling Quasar ARM) fundamentally depends on the quality of manufacturing and layout of the printed circuit board (there are more than ten options sold, and not all are good), the quality of components and installation, and especially - on the quality of the sensor. Therefore, it is funny to read negative reviews about the device as a whole, based on the experience of assembling clumsy parts from parts found in the trash. Moreover, judging by information from various specialized forums, such ugly crafts make up the bulk of the instruments and sensors offered for purchase. Faster, cheaper, and that will do - apparently, this is the main goal of most sellers (I by no means speak for everyone). Of course, this approach entails a lot of negative reviews about the device, although it would be wise to write a review about the manufacturer. To set up a Quasar workstation well and make a decent sensor, you need not only knowledge and experience, but also normal measuring equipment, not to mention the ability to use it. Craftsmen often make do with a Chinese tester from a flea market... this is also possible, but is it worth expecting a good result? Another point, many “Kulibins”, without even having basic knowledge in the field of electronics, try in every possible way to “modify” and “improve” the author’s circuit (I often cite it as an example of high-quality development), created by a professional. Based on these, so to speak, improvements, printed circuit boards are then hastily laid out and immediately put on sale. What can I say... only that such crafts have nothing to do with the real Quasar ARM and any reviews about such “Quasars” are nothing more than a painting of one’s own incompetence. Here and further we will talk exclusively about devices assembled with direct hands according to the author’s scheme.

Review of the Kvazar ARM metal detector

Quasar AWP, assembled by me on the author's board revision 1.4, the firmware current at the time of writing this review is version 2.2.10. A family of homemade sensors from a sniper rifle to a “steering wheel” for medium frequencies of 7..9 kHz. The scheme is the author's, no changes.

I can immediately responsibly declare that a Quasar AWP correctly assembled from high-quality components, equipped with a well-made sensor, has search characteristics that are often superior to the top devices of leading manufacturers in their segment (single-frequency ground-based IB devices). This does not negate the mandatory understanding of the principles of operation and the ability to configure the Quasar workstation for specific conditions, as, indeed, any branded metal detector.

In addition to Quasar ARM, I collected and tested analog devices such as Tesoro Vaquero and Lobo, Whites Classic in different variations, some ancient Fisher... they were all single-tone, I personally didn’t like it. The plans are to build something like Golden Mask 4, two-tone analog... but these are plans. From digital cameras I collected Quasar AVR, pulse variants of Clone (author Andy_F), Fortuna-M. Among the branded ones were “Koshchei-25K”, Terka-705, I tried new digital Whites, now I use Deus (studied and touched up and down). This is all to say that I have something to compare with. It may seem to some that I am “singing praises” to the device... this is not so. He, like everything in the world, has shortcomings, I will definitely write about them. Therefore, without false modesty, I can say that my review of Quasar AWP will be objective and honest.

So, from the very beginning.

Schematic diagram. As an electronics engineer by training and hobby, I rate the circuit 4.9 points out of 5.0. Here it is appropriate to quote a teacher-professor: “Only the Lord God knows the strength of materials perfectly, I know a B, and all of you (students) know a C at best!” No matter how much I looked at the diagram, I couldn’t improve anything (I’m not a guru, of course, but I have experience in development and implementation in production). Do it differently - yes, but improve it - no.

Printed circuit board. From the point of view of signal wiring, the author’s one is good, but it’s a little difficult to make on your own due to the large number of via holes, and it was also originally designed for a non-standard and scarce type of display. You can install a regular one on it, with a couple of “extra” wires, this is not critical. Otherwise, it’s one of the best, if not the best. There will be a separate review about all other boards.

Components used. Widespread, not scarce and not expensive. The total cost does not exceed $40 if you buy everything new. It is better to use an OLED display, but it is somewhat more expensive than a regular LCD.

Repeatability. High... no, highest. Everything works without any adjustments to the hardware, the main thing is to assemble it correctly from serviceable components and properly rinse the board from flux. The operation is practically independent of the variation in the parameters of the parts - a sign of a high-quality circuit design.

Flexibility of settings. Everything you need for an effective search. It is especially worth noting the perfectly working sensor imbalance compensator (allows you to work normally even with a “floating” sensor, or with an “almost suitable” factory one), switchable automatic ground balance with adjustable reaction time, a set of ground filters (speeds) for all occasions, 8 memorized profiles , arbitrary mask for voice acting. Vector cutting of soil, allowing you to very accurately “cut” it without loss of range (well, almost without loss). There is a static pin mode with discrimination and VDI display. The set of settings corresponds to a professional level, so it is advisable to understand the issue a little and not use it at random. However, by default everything is fine.

Voice acting, display. Three voice-over schemes, including polyphony (scheme 1), which I consider the most informative. The sound is soft and pleasant. Adjusting the volume of weak signals, several additional ones. options, including thrashhold. 16-sector signograph, display of VDI number, signal strength, battery charge level, current ground angle, transmitter current. Signograph display delay adjustment. Again we see a set for a professional. Very informative and convenient. The latest versions of the circuit and board have a built-in FM transmitter for using wireless headphones. It works great, all adjustments are in the menu. Do you know many devices with wireless “ears” by default and with transmitter adjustments?

Depth. Depends on the settings, mainly on the filter. The threshold also affects. The slower, the deeper. On the slowest filter with threshold 3, with a DD25cm sensor, you can “feel” a patch of tips at 35..38cm. This is in light soil, for example, Deus with a 28cm sensor catches only barely better, “at the end”, at similar “depth” settings.

Identification and division of goals. In fact, everything here depends more on the sensor and settings. But if we compare with identical sensors, then at maximum speed the Quasar ARM approximately corresponds in speed to the Deus in “second gear”, that is, Reactivity = 2 (out of 5). Very good, with a small sensor on the garbage it is very comfortable. The separation with the appropriate filter settings is excellent, the separation of color against the background of black signals is also at the Deus level, no subjective differences were found. If they see, then both devices, if they don’t see, then both.

Stability, overall comfort. On high. If the same Deus with “quiet” settings turns into a pumpkin, then the Quasar ARM almost does not lose in depth. That is, with a normal Quasar, it is more comfortable to search for an automated workplace than with a Deus, this is in clean places. In the trash, Deus has no equal, but if there are not many signals, you can walk with Quasar in almost silence, and Deus will be a little babbling - but he is also somewhat deeper. Quasar ARM is one of the most comfortable in search of all the devices that I have had.

Flaws. What would it be like without them... true, they are all subjective, but still. To begin with, I don’t like the small number of voice-over schemes and the inability to customize the frequencies and volumes of the sectors to suit you. In the same Koshchei-25K, Fortuna-M it was and it’s convenient. I really hope that the author will eventually listen to this opinion, it is not only mine. Then the speed, it (after Deus) seems a little insufficient for strong trash cans. In pin mode, sometimes (rarely) it “starts up”, it is cured by resetting it with the “left” button (this binds to the current response level). I’m attracted to the ears: for an effective search it requires some knowledge in this area, an understanding of the physics of processes. However, like any other professional device.

Conclusion: Quasar ARM is, in my opinion, the best of the home-made devices in terms of the totality of characteristics. No more, no less.

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