New Simple Metal Detector Electronic Manufacturing Kit DIY Metal Detector Loose Parts BoardItem NO.: Metal Detector

New Board Simple Metal Detector Kit

Kit parameters:

Power supply voltage: 3-5 V;

External dimensions: 66 * 61MM;

Detection distance: 5CM;

Special reminder: This kit is positioned as an electronic teaching kit, mainly used for connecting welding and learning working principles. It cannot be used for treasure exploration, and the sensing distance is within 5 centimeters.

This product is for welding loose parts and requires some electronic knowledge and welding skills. Novices are not allowed to take photos without technical knowledge. After welding, it cannot be returned or exchanged!!

Q1, L1, L2, C2, C3, R1, and W form a high-frequency oscillation circuit. By adjusting the potentiometer W, the gain of the oscillation stage can be changed to put the oscillator in a critical oscillation state, which precisely causes the oscillator to start oscillating. Q2 and Q3 form a detection circuit. When the circuit oscillates normally and the oscillation voltage AC voltage exceeds 0.6V, Q2 will conduct in the negative half cycle and short-circuit C4, resulting in Q3 cutoff; When the detection coil L1 approaches a metal object, eddy currents are generated in the metal conductor, causing an increase in energy loss in the oscillation circuit, weakening positive feedback, weakening the oscillation of the oscillator in a critical state, and even being unable to maintain the required energy for oscillation, causing Q2 to cut off, R2 to charge C4, Q3 to conduct, and push the buzzer to sound. Based on the presence or absence of sound, it can be determined whether there is a metal object underneath the detection coil.

According to this principle, this circuit can be effectively modified into a proximity switch for elevator floor control. (In many situations, photoelectric switches are not suitable because they are affected by environmental dust and can block light-emitting and light-receiving devices.)

For example, the principle of this metal detector can be used to detect the presence of cars on a certain road surface. Due to the height of the car chassis from the road surface being 0.5 meters or more, and the depth of 5-10cm buried in cement, burying a coil with a diameter of 1 meter on the ground can stably, accurately, and reliably detect the presence of cars on it. This has practical value in highway flow statistics and parking lot no stop area statistics.

Example 2 of the principle of this metal detector: A sensor is required on each floor of the elevator controller to detect whether the elevator has reached the stop position. If a mechanical travel switch is used, there will be factors of lifespan and reliability; If optocouplers are used, there will be long-term dust deposition faults; Therefore, a good method is to install a metal detector and determine the on/off of the circuit based on the presence or absence of metal. This has high practical value in many devices and machines.

1. Double sided wiring, solder pads sprayed with tin, and multiple soldering of solder pads is not easy to fall off;

2. It is not easy to undergo self bending (referring to bending caused by non human factors), and poorer boards will develop over time and environmental changes

Bending.

3. Impedance is more stable and reliable

Debugging method after welding:

The L1 and L2 of this machine use copper wire on the printed board to form inductors, without the need for everyone to make their own inductors. It is simple and has a high success rate! The circuit has just used more than ten components, and as long as they are installed correctly, they can generally work normally. After installation, connect the power supply and adjust the potentiometer until it just doesn't make any sound (not close to metal). Use printing