Pulse induction metal detector DIY based on ATTINY13

The experimental project demonstrates how to build a simple PI (pulse induction) metal detector based on the ATTINY13 / AVR microcontroller. My goal is to make the circuit as simple as possible, and only popular / cheap electronic parts. The device has been tested by very small coils and only 3V power sources. This is my first design for PI metal detectors, I am very satisfied with the results! The prototype can detect small coins (6cm distances) and wires on the wall. How does this work? The proposed metal detector uses the PI method to generate voltage spikes in the search coil parallel to the capacitor. Next, Attiny13 uses an analog comparator to measure the time of resonance circuit attenuation to zero. When the metal object is approaching the loop, it will reduce the time spending pulse attenuation to zero. Measure the change in resonance time width to emit a signal of a metal target. Please note that typical PI detector is designed to avoid resonant circuits, and the measurement factor is slightly different! Instructions for use Open the device. The calibration process takes approximately a second and ends with the buzzer signal. Use variable resistors to adjust the sensitivity of the detector (you can find it between continuous buzzers and complete mutes). The equipment is ready! Required parts ATTINY13 - MBAVR-1 development board T1 - IRF3205 (MOSFET; N channel) LED1 - basic LED D1 - 1N4007 D2, D3 - 1N4148 R1 - variable resistance 10kΩ R2, R3-220Ω (5%) R4 -330Ω (5%) R5, R6 -10KΩ (5%) C1 - 470NF L1-∅50-55mm, about 30 to 0.5 DNE Circuit schematic Be Copyright Notice: Circuit City Original compilation, translation from HackADAY, please indicate the source!

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