Terminator 3 is a coin searching metal detector that operates according to the induction balance principle (IB). The “Terminator-3” scheme was developed based on the Tesoro metal detector. However, there are significant differences from these metal detectors, both in its work principle, in the process of its manufacture or configuration.
The main advantage of the Terminator-3 metal detector is the ability to recognize metal at the limit of sensitivity (even with a minimal capture of the target, it accurately detects its kind).
Technical characteristics of the metal detector Terminator 3
– Principle of Operation IB (Induction Balance)
– The search modes “Discrimination” and “All Metals” are switched.
– Operating frequency 7–20 kHz (Depends on the coil and capacitors C1 and C2).
– Power 9-12 V.
– Manual ground balance
– Depth of detection of objects in the ground with a coil of 240 mm:
– Coin 5 Russian rubles – 22-24 cm.
– Coin 5 kopecks Catherine – up to 30 cm.
– Helmet – up to 80 cm.
The division of the VDI scale in the Terminator-3 metal detector is graphically presented below.
Terminator- 3: scheme and part list
Terminator-3 is quite difficult to build it yourself. It will be extremely difficult for a beginner to do this. We recommend collecting this scheme for amateurs who have experience in the manufacture of metal detectors!.
C1.1 – 330nf c16 – 220nf c33 – 680nf C1.2 – 330nf c17 – 220nf c34 – 1500mf x 10v C2.1 – 150nf c18 – 220nf c35 – 470mf x 10v C2.2 – 15nf c19 – 220nf c36 – 470nf C3 – 3,3nf c20 – 2,2m c37 – 1000mf x 6,3v C4 – 3,3nf c21 – 470nf c38 – 1000mf x 6,3v C5 – 1000pf c22 – 470nf c39 – 470nf C6 – 120pf c23 – 47nf c40 – 1mf x 160v C7 – 560pf c24 – 47nf c41 – 2,2mf C8 – 39pf c25 – 4,7nf c42 – 560pf C9 – 360pf c26 – 4,7nf c43 – 330pf C10 – 1000pf c27 – 470nf C11 – 1000pf c28 – 470nf C12 – 412pf c29 – 47nf C13 – 10nf c30 – 47nf C14 – 10nf c31 – 680nf C15 – 2,2nf c32 – 680nf
R1 – 100k r16 – 30k r31 – 470k R2 – 22om r17 – 1k r32 – 47k R3 – 100k r18 – 100om r33 – 47k R4 – 10k r19 – 15k r34 – 470k R5 – 300k r20 – 15k r35 – 470k R6 – 2,4k r21 – 5,1k r36 – 30k R7 – 100k r22 – 47k r37 – 30k R8 – 100k r23 – 47k r38 – 24k R9 – 2,4k r24 – 470k r39 – 10k R10 – 1,5m r25 – 470k r40 – 24k R11 – 1,5m r26 - 47k r41 – 15k R12 – 100k r27 – 1k r42 – 24k R13 – 110k r28 – 47k r43 – 100k R14 – 470k r29 – 330om R15 – 100k r30 – 470k
ICs Transistors Diodes
Мс1 – HEF4069UBP VT1 – BC327-40 VD1 – 1N4148 MC2 - HEF4069UBP VT2 – BC327-40 VD2 – 1N4148 MC3 - HEF4069UBP VT3 – 2SC4204 VD3 – Led MC4 – 74HC4066N VT4 – BC517 VD4 – FR157 MC5 - HEF4069UBP MC6 - HEF4069UBP MC7 - HEF4069UBP MC8 – LM193N MC9 – KP1170EH6 MC10 – KP1171CП64 MC11 – TL431ACLP
In addition, to create a Terminator-3 metal detector with your own hands, you need to prepare:
– Multimeter with capacitance measurement;
– LC meter.
Printed circuit board (PCB)
Several versions of PCB breeding for the Terminator-3 metal detector can be downloaded from the archive at the end of the post.
The capacitors on the board must be metal-film with high thermal stability. In addition, it is recommended using a tester to select the most identical parts in terms of parameters on two parallel amplification stages and the values of the capacitors C1 and C2, so that everything is as identical as possible. This will greatly facilitate your setup. As a tuning resistor, it is better to use multi-turn.
After soldering the metal detector, the board must be washed with alcohol, dried and visually checked for defects or any shot-circuit.
Then without a search coil, it is already possible to check its performance. For this:
1- Turn on the metal detector.
2- We unscrew the sensitivity regulator until a constant sound appears in the dynamics.
3- We touch the fingers of the sensor connector, the sound should be interrupted for a second.
4- When turned on, the LED should blink and turn off.
If so, and the board is soldered correctly. Now you can begin to manufacture the search coil.
Building a coil for the Terminator-3 :
TX – transmitting coil. Diameter 200mm
number of turns: 30 turns with a double folded wire
wire diameter: 0.4 enamelled winding
RX – receiving coil. Diameter 100mm
Number of turns: 48 turns with a double folded wire
Wire diameter: 0.4 enamelled winding
CX – compensation coil
Wire 0.4, wound on a mandrel from TX, the number of turns from 20 and rewind when setting the balance.
Both the transmitting and receiving coils are wound with a double wire (that is, 4 ends of the wire should be obtained), the shoulders of the windings are determined by the tester and we connect the beginning of one shoulder with the end of the other, we get the average output of the coil. The average output of TX is connected to the minus (Ground) of the board (without this, the generator will not start), the average output of RX is needed only for tuning in frequency, after tuning in frequency (resonance) it is isolated and the receiving coil turns into normal (without output). The receiver for tuning is connected instead of the transmitter and tuned to 100Hz-150Hz below the transmitter. Balancing is carried out by a compensation coil by unwinding coils from it after all frequency settings. The balance should be within 100mv.
We spill the sensor with epoxy resin, but only at half the depth of the mold. After solidification, we connect the oscilloscope, bend our loop into the form and begin to twist it, trying to find the minimum amplitude value. After the position is found, fix the loop with glue, re-check the balance and fill our form to the end.
below the finished home-made coil for a metal detector Terminator-3.
Firstly, after balancing, check the connection. The metal discrimination knob is set to zero, the ground balance knob is in the middle position, the feeling knob is adjusted, the mode dial is in the “color only” position.
We take a piece of ferrite 1x1cm and some copper pieces. We turn on the device and the first wave the ferrite over the sensor, then the copper. There should be a double beep on ferrite, and a single beep on copper. If vice versa – then we change the ends in TX places.