Circuits & Schematics: metal detector - 3

21. Short Range Hand Wave Detector
    Circuits Domestic LMC7211 LM358
    .. I would not recommend its use in direct sunlight. Two small PIN photodiodes positioned about one inch apart form a shadow detector. With no shadow cast on the devices, both devices produce nearly identical current levels. The current is ...
    Mar 31, 2009

22. Cellular Phone calling Detector
    Circuits Domestic Cellular
    Flashes a LED when detecting an incoming call Powered by one 1.5V cell Circuit diagram : Parts: R1 100K 1/4W Resistor R2 3K9 1/4W Resistor R3 1M 1/4W Resistor C1, C2 100nF 63V Polyester Capacitors C3 220µF 25V Electrolytic Capacitor D1 LED ...
    Jul 6, 2009

23. Energy Leak Detector
    Circuits Domestic Measurement
    .. around doors and windows that cause energy leaks but can be used in many other ways, when a sensitive temperature change detector is needed. Two LEDs are used to signal if the temperature change is pointing above (Red LED) or below ...
    Jul 21, 2009
24. First-event detector has automatic-reset function
    Circuits Domestic Games
    Use this circuit to tell which game player presses a button first. Vasil Borodai The circuit in Figure 1 lets you indicate which game player presses a button first. Each button has a corresponding LED that indicates the pressing of the button. All ...
    Aug 6, 2009
25. Precision Peak Detector Uses No Precision Components
    Jim McLucas
    Circuits LM306
    .. you need a precision peak detector, you would usually implement it with one or several op amps and a few other associated components. This ...
    Dec 20, 2009
26. Room Noise Detector
    Circuits Security Measurement
    One LED monitors three levels: 50, 70 85 dB Useful to detect too noisy environments Circuit diagram: Parts: R1 10K 1/4W Resistor R2, R3 22K 1/4W Resistors R4 100K 1/4W Resistor R5, R9, R10 56K 1/4W Resistors R6 5K6 1/4W Resistor R7 560R 1/4W ...
    Apr 5, 2010
27. Live-line Detector
    Circuits Measurement CD4017
    Detects the presence of a live mains conductor Minimum parts counting Circuit diagram: Parts: C1 100nF 63V Polyester or Ceramic Capacitor D1 Red LED (any type) IC1 4017 Decade counter with 10 decoded outputs IC P1 SPST Pushbutton B1 3V Battery (two ...
    Apr 4, 2010
28. Motion detector alarm
    Circuits Security
    .. Mohankumar This motion detector alarm circuit can detect a moving person from a distance of 1 meter. It uses a Dual IR ...
    Sep 21, 2010
29. Dual comparators stabilize proximity detector
    Arthur Harrison Joseph Stern
    Circuits Measurement Maxim MAX406ACPA MAX912
    .. the proximity detector of Figure 1, a 4-in.-sq piece of copper-plated pc board serves as an antenna that forms one plate of a ...
    Dec 29, 2022
30. AC Power Current detector Circuit with LM1458
    Circuits Measurement Power
    This circuit will detect power line currents of 250 mA or more without making electrical connections to the line. Current is detected by passing a line of alternating current through an inductive pickup (L1) as a screen diameter of 1 inch U-bolt ...
    Dec 5, 2010

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