Induction Balance Metal Detectors

Metal detector Qasar AVR microcontroller

Metal detector Qasar on the AVR microcontroller

The Quasar metal detector is a microcontroller-based IB metal detector designed with available electronic components. The metal detector uses a selective (selective) mode with audible multi-tone indication. There are 2 versions of the quasar metal detector circuit on the Atmega32 microcontroller and the STM32 microcontroller

Scheme of the Kvazar metal detector on the AVR microcontroller

Metal detector Qasar  AVR microcontroller

List of parts for assembling the metal detector quasar AVR

Designation Type of component
R1 resistor 100 ohm
R2 resistor 2 kΩ
R3 resistor 100 Ohm *
R4 resistor 470 Ohm
R5 resistor 4.7 k Ohm
R6 resistor 1.2 k Ohm
R7 resistor 100 kΩ
R8 resistor 330 Ohm
R9 resistor 47 k Ohm
R10 resistor 10 kΩ
R11 resistor 1 kΩ
R12 resistor 62 Ohm
R13 resistor 1 kΩ
R14 resistor 1 kΩ
R15 resistor 100 kΩ
R16 resistor 3.6 k Ohm
R17 resistor 1.2 k Ohm
R16 resistor 3.6 k Ohm
R18 resistor 1.1 k Ohm
R21 resistor 10 kΩ
R22 resistor 1.5 k Ohm
R24 resistor 100 ohm
R25 resistor 10 ohm
R26 resistor 25 ohm
R27 resistor 25 | sum50 ohm
R28 variable resistor 10 kΩ
R29 resistor 10 kΩ
C2 capacitor 0.033
C3 capacitor 0.1
C5 capacitor 0.1
C6 capacitor 0.33 *
C7 capacitor 2200
C8 capacitor 1.0
C9 capacitor 0.1
C10 capacitor 47
C12 capacitor 0.1
C15 capacitor 0.1
C16 capacitor 0.1 (!)
C17 capacitor 0.1
C18 capacitor 22
C19 capacitor 0.1
C20 capacitor 0.1
C21 capacitor 22
C22 capacitor 0.47
C23 capacitor 0.1
C25 capacitor 0.1
C27 capacitor 0.1
C29 capacitor 0.1
C32 capacitor 0.1
C11 electrolytic capacitor 2200x10V
C13 electrolytic capacitor 1500x10V
C14 electrolytic capacitor 2200x10V
C33 electrolytic capacitor 1000x16V
C34 electrolytic capacitor 1000x16V
D1 diode 1N4148WS
D2 diode LED
D3 diode 1N4148WS
D4 diode 1N4148WS
D6 diode 1N4148WS
D7 diode SK16
D8 diode HER…, MURS…
D9 diode HER…, MURS…
VD1 diode 1N4148WS
VD2 diode 1N4148WS
VD3 diode 1N4148WS
VD4 diode 1N4148WS
Q1A, Q1B transistor assembly IRF7105 / SO
Q2 transistor BC846BL
Q3 transistor BC857BL
Q4 transistor BC846BL
U2 chip TL431
U3 chip LP2950
U4 chip MCP3201
U5 chip ATmega32A
U7 chip LM2941S
U8 chip MCP633
C1 capacitor 0.1
LCD display
RC1602A with controller HD44780 or KS0066
SW1-SW6 4-pin buttons
BQ1 quartz 11.0592

The assembled metal detector looks like this

  • Metal detector Qasar  AVR microcontroller

Button functions


  • SW1 :  UP / Barrier + / Autotune
  • SW2 :  Enter / OK / Ground balance
  • SW3 :  Right (+) / PinPointer
  • SW4 :  Left (-) / Backlight
  • SW5 :   Menu / Esc
  • SW6 :  Down / Barrier- / Autotune

Setting fuse bits in PonyProg

Metal detector Qasar  AVR microcontroller

In the download section, Under microcontroller AVR there are two versions of the printed circuit board under the dip and SMD housing.
Printed circuit boards of the metal detector on the AVR microcontroller for dip and SMD cases in .lay format.

Search coil for metal detector Quasar

Metal detector Qasar  AVR microcontroller

The coil diameter is 230 mm. The coil consists of 2 parts: (DD coil)

  • transmitting TX – consists of 40-45 turns with 0.5mm wire;
  • receiving RX – 200 turns with 0.2 mm wire.

The TX transmission circuit is switched on according to the scheme with a serial oscillatory circuit with a capacitance of 0.3 μF. The frequency of the transmitting circuit is 8.192 kHz, but it can operate in the range of 4.5 – 9 kHz.

The RX receiving circuit is a parallel oscillatory circuit, tuned to a frequency below the TX circuit by an amount of the order of 1.5-2 kHz.

The assembled coil looks like this

Metal detector Qasar  AVR microcontroller

After winding, the coils should be filled with epaxidic resin, which will give shape and strength, as well as protect against moisture.

Download files


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