This Pinpointer KB_V3_VCO is a simple precision target location device that can be manufactured at home. It has one integrated circuit which is available in all stores and has many alternatives that can be found easily. It has a range of detection about 5 cm for a coin which is very suitable for searching on dust and sand. The device has dynamic search mode, and when you approach the target the mode becomes static.
Below is a pinpointer schematic for home manufacturing as well as a printed circuit board PCB which can be downloaded at the end of this post.
The following board helps to put the pieces correctly:
|C1 ، C5||Capacitor||0.1 uF||2|
|C9 ، C10||Chemical capacitor||10 uF
|C11||Chemical capacitor||100 uF
|R1||Variable resistor||4.7 KOhm
|R2 ، R8||resistor||4.3 KOhm
|R3 ، R3||resistor||680 Ohm||2|
|R4 ، R13 ، R14||resistor||1 ميجا أوم||3|
|R5 ، R6 ، R11||resistor||10 KOhm
|R7 ، R16 ، R17||resistor||100 KOhm
|R10 ، R12||resistor||22 KOhm
|R15||Variable resistor||47 KOhm
The value of the R3 is selected according to the maximum sensitivity for the search coil made from 5 cm ferrite rod, 8 mm of diameter and 320 turns using a 0.3 mm insulated copper wire.
An additional coil can be made on a 40 turns with an insulated copper wire of diameter 0.14 mm and 150 turns and the resulting frequency is about 20 kHz.
The device Consumes about 5.5 mA and with the sound and light signal is around 10.5 mA.
After installing the device it will look exactly like the one in the following picture:
Using this detector, different types of coils and different sizes have been tested (when changing the coil, the variable resistance R1 must be tuned), the coil (200 mm diameter, 80 turns with wire diameter 0.5mm), the pinponter detect a PCB board at a distance of 300 mm. Generally the device works with any coil and the frequency can be adjusted from 15kHz to 20kHz.