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One type of metal detector is a type of beat frequency oscillator (BFO). The methods used in metal detectors in general are changing the characteristics of the oscillator when there are close to the metal sensor. The detector works based on the resonant frequency that has been set change when there is a metal object is located quite close to the search coil sensors. Tuning circuit (tuned circuit) should be a part of our oscillator circuit so that if approached by a metal coil sensor specific hence the output frequency of the oscillation circuit is about to change. Variation changes the output frequency depends on the frequency chosen. The selection of the higher frequency will cause the circuit sensitivity increases because the greater the frequency change. Stay if the selection frequency is too high then the practice will produce a system that is not sensitive. This is because the high frequency of most will not be reflected back but will be absorbed by the soil, building materials. M...

This metal detector circuit diagram is designed using on a transistor radio as an detector. L1 search coil of the metal detector must have 18 turns from a 0.65 mm enameled wire scrambled on a 4 inch diameter support . The C1 capacitor is a variable capacitor with a value of 365 pF, C2 is a 100pF silver mica capacitor , C3 is a 0.05 uF disc capacitor and the C4 is a 4.7 uF capacitor . Radio Metal Detector Circuit diagram The Q1 transistor can be RCA SK3011 npn transistor or equivalent type and all resistors need to be ½ watts . With the radio tuned to a weak station you must adjust the variable capacitor C1 until the locator oscillator beats against the received signal. If a metal is detected the inductance of the L1 coil is changed, changing the frequency of the locator oscillator’s, resulting a change in the beat tone radio .

This metal detector circuit consists of two oscillators, both working at about 465 kHz. One uses a transformer and the other uses an inductor which is the search coil LI. The oscillators are coupled through a capacitor 10 pF. The circuits DE metal detector is a BFO (beat frequency oscillator), a tone beat produced if the two oscillators are working together through the diode is detected and sent to the audio amplifier.   BFO Metal detectors Circuit Diagram The oscillator coil is tuned by a variable capacitor of 10-365 pf variable. The search coil is made of wire with 22 turns between 24 and 36 AWG enamel junction to the center. The wire should be wound on a form of about 6 "χ 6" and the phones must be high impedance.

Samsung announced its new phone Samsung Galaxy Note 4 focusing on providing better and no drastic changes. The Samsung Galaxy Note 4 features the same screen size as the Galaxy Note 3 (5.7 inches), but now integrates a QHD screen (2K), the same resolution offered by the LG G3 today. Additionally, the Galaxy Note 4 features a new metal frame that gives you much more elegance though other components are primarily made ​​of plastic. This reminds us a little Samsung Galaxy Alpha, the frame design is not exactly the same. He also is the first phone with Snapdragon processor 805 that bind outside the Asian market. The processor is 2.7GHz. Also find and 3GB RAM, 32GB of storage (with optional 64GB), microSD card support up to 128GB Android 4.4 and KitKat. Samsung has integrated fast battery charging battery in 30 minutes would allow about 50 percent of the battery that has a capacity of 3,220mAh. The cameras have also improved in many aspects. It's not just the fact that the rear camer...