“A relatively sensitive IB (Induction balance) Metal Detector which is very easy to make, and contains a few standard electronic components
In the previous period, I presented several types of metal detectors that were based on microcontrollers and Android smartphone. This time I will present you a relatively sensitive IB (Induction balance) Metal Detector which is very easy to make, and contains only a few standard electronic components.
The project is based on “Matchless metal locator” Metal detector by Thomas Scarborough published in Silicon Chip Magazine in 2012.
First I made the original project which has relatively good features and then I modified it by adding a Power Mosfet in front of the Tx coil. This modification gives about 30% better sensitivity, but the most important thing is that the stability is drastically increased, so now there is no need to frequently adjust the operating point of the device. But I must point out that the downside is that consumption has increased several times and now is around 50 milliamperes, but since I use large capacity lithium-ion batteries, this is not a problem. Instead CMOS ICM7556 IPD, I use 2 pcs. of standard 555 Timer ICs with a slightly lower result, which is compensated by the above modification. The coils for this metal detector are identical and contain about 60 turns of lacquered copper wire with a cross-sectional area of 0.4 mm^2 wound in a circle with a diameter of 15 cm. The coils are then bent and folded into a double D-shape.
As I mentioned before the device is very simple to make and contains a very small number of components:
- Two standard 555 Integrated circuits
- One universal NPN transistor
- One Power MOSFET
- Three Potentiometers
- And several resistors and capacitors”