This device is a precise Pinpointer indicator for the exact location of the detected metal. The principle working is very simple, for people looking for coins and small objects in the ground and but can not buy a commercial pinpointer. This works well and many of its parts are available. In this post there is everything necessary to build it from the diagram to printed circuit board PCB that can be downloaded at the end of the post.
According to the schematic of the device, I think there will be no questions or problems in the building, just all components should be installed on the printed circuit board PCB, paying attention to some details on the board that should fully comply with the schematic.
All capacitors used in the device must be film-type with an operating voltage of at least 100 volts.
Technical specifications Pinpointer MINIMAX-PP-II
Pinpointer Minimax PP-2 is a simple, reliable and compact metal detector developed by a member of the forum on md4u under the name Petrucho. Tested on land and in water, works great in salt water and soil.
Let us know the technical characteristics of the device:
- Consumption ……….. 18 mA;
- Alarm signal. Sound (fixed tone);
- Detection of coins ………….. 5 cm.
A short video an the end shows its performance characteristics.
The printed circuit board PCB can be made from the schematic. But do not tire yourself because we will include them in the last post to download
According to original printed circuit board PCB, it is used on one side with a combination of normal components DIP and SMD .
Search coil for Pinpointer MINIMAX-PP-II
For the coil L1 , you can use a piece of ferrite rod, a diameter of 10 mm removed from the magnetic antenna of an old radio as shown in the picture.
The length of the rod is 10 cm, and the coil is made from 4 layers, with an insulated copper wire with a diameter of 0.35 mm. The total number of turns is 450. After the winding process, we squeeze the coil well so that it shrinks and doesn’t leave spaces between the turns.
After some experiments and verifying that the circuit is running properly, it is necessary to impregnate the coil L1 with epoxy or varnish. This will give the search file stiffer and more stable.
The pinpointer refers to an existing metal target with an acoustic signal. This sound is generated by a beep (a piezoelectric element with a built-in sound frequency generator) with an operating voltage of 5-6 volts.