Here we introduce a metal proximity switch circuit that is widely used in the machinery industry, as shown in the figure. The circuit consists of two parts, namely a high-frequency oscillator and a switching circuit, and its working principle is as follows. 
When the metal is not close to the probe, the high-frequency oscillator works, the oscillating signal is rectified by the voltage doubler of DV1 and DV2, and the DC voltage is obtained to make BG2 turn on, BG3 cut off, and the subsequent circuit does not work. When there is metal close to the probe, due to eddy current loss, the high-frequency oscillator stops vibration, BG2 is cut off, BG3 is electrically turned on, the photocoupler 4N25 has a built-in luminous tube to emit light, and the phototransistor is turned on to turn on the circuit and play a switching role.
The component selection probe needs to be self-made. It is wound on the φ5mm & TImes; 4mm magnetic core with φO.12mm enameled wire. The number of turns is as shown in the figure, and other components are marked as shown in the figure. Generally, as long as the components are good and the welding is correct, it can work normally.
Debug and switch on the power supply, adjust W1, and monitor BG2 with a multimeter to make the two poles c and e fully conductive. At this time, the high-frequency oscillator is in a weak state. Then close the probe with a metal object, BG2 should be cut off immediately. Then fine-tune W2 to make BG3 fully conductive. At this time, the sensitivity is high and the range is large (the sensing distance is a few millimeters to tens of millimeters). Then, according to your own use, carefully adjust W1 and W2 to make the sensing distance suitable for your use can.
3.0mm Wire To Board Connectors
3.0mm Wire To Board Connectors are avialable in different terminations and sizes intended for use on a variety of applications. These connectors provide power and signal with different body styles, termination options, and centerlines. To find the wire to board set required, click on the appropriate sub section below.
3.0mm Wire To Board Connectors Type
3.0mm Terminal
3.0mm Housing
Pitch 3.0mm Wafer Right Angle&SMT Type
3.0mm Wafer Straight Type
3.0mm Wafer SMT Type
3.0mm Wafer Right Angle Type
3.00mm Wafer Single Row Straight Type
3.00mm Wafer Single Row SMT Type
3.00mm Wafer Double Row Straight Type
3.00mm Wafer Double Row SMT Type
3.00mm Wafer Double Right Angle Type
3.00mm Wafer Double Right Angle&SMT Type
3.0mm Wire To Board Connectors Advantages
Small electronics with high current requirements
One of the strongest advantage of the Micro Fit series is its applicability in delivering the high current requirement in electronics with supplying high power.
Safe and Reliable
ensure safety, system protection and performance with its bonded metallic conduits and multiple grounding points preventing fire hazards, component damage, overheating and possible electrocution.
ROHS Compliant
The product does not contain restricted chemicals in concentrations not complying with ROHS standards. Thus, for its components, the products can be worked upon at high temperatures required by lead-free soldering.
3.0mm Wire To Board Connectors Application
Motherboard Connectors
The Motherboard of a computer holds together many of the crucial components such as the central processing unit (CPU), memory and connectors for input and output devices. Microfit connectors ensure high performance electronic system in quality motherboards.
You can easily find Scondar`s Microfit in most ITX Motherboards, in which its functionality is best described for solid performance in a small footprint, and low power consumption (less than 100 Watts).
Printer Connectors
The 3.0mm Microfit can also be seen in most printers
Automotive PC Connectors
Smart, high power automotive PC power supply garners its capabilities from quality Microfit connectors, designed for general purpose battery powered applications. These are manufactured to provide power and to control the motherboards' switch based on ignition status.
Solar Panels
Microfit can also be commonly found in a solar array. A solar array is connected to each other, and to inverters through connectors to produce a successful flow of electricity.
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