Circuits & Schematics: metal detector - 4

31. Detect wire breaks with unusual CMOS gate circuit
    Circuits Measurement Texas Instruments CD4050B CD4069UB CD40106B
    .. memory cell, we shall explore a way of detecting such a break. In Figure 2a, the broken wire forms a capacitance with a detector cylinder of length 1-3 cm through which the wire passes, and charges the input capacitance (C I ~10 pF) ...
    08-01-2023

32. Dual comparators stabilize proximity detector
    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 ...
    29-12-2022

33. Oscillating Output Improves System Security
    Circuits Automation Security Vishay IRFD110
    .. the low-frequency dynamic variable from the PLC. To accomplish that task, you must use an external oscillator and a pulse detector implemented with a monostable multivibrator. The oscillator produces a square-wave signal of a frequency ...
    19-12-2022
34. Solenoid Trip Circuit Works at Battery's End of Life
    Circuits Supply Texas Instruments LP339 TLE2426
    .. Design Idea involves a low-power motion-detector circuit that operates from battery power for extended times. Part of the design includes a ...
    12-12-2022
35. Simple Continuity Tester Fits into Shirt Pocket
    Circuits Measurement Central Semiconductor 2N5087 2N5089
    .. than 100 Ω. Unfortunately, a continuity tester may create noise currents that feed back into the sensitive Q 1 /Q 2 detector. Three circuit features minimize that noise. First, capacitor C 2 connects across the buzzer. Second, ...
    09-12-2022
36. AC Voltage Zero Cross Detector
    Circuits Supply Rohm BM2P129TF BM1Z102FJ
    .. V DC @ Maximum Load 100 mA PCB Dimensions 58.90 × 28.73 mm Schematic Figure 2. Schematic of the AC VOLTAGE ZERO CROSS DETECTOR. Connections Figure 3. Connections. Application circuit Figure 4. Typical application circuit. Waveforms ...
    30-11-2022
37. Analog Peak Detector Frames Mechanical Bounce, Quantifies Contact Resistance
    Circuits Analogue Design Measurement Texas Instruments LF411 LM324 LM358
    .. subsided. The circuit of Figure 1 allows analysis of noise or mechanical bounce within time intervals set by a simple peak detector with an associated comparator. Switch-contact resistance then can be read automatically through the ...
    25-11-2022
38. Improved current monitor delivers proportional-voltage output
    Circuits Measurement Supply
    .. kept the circuit from oscillating until primary current flow ceased. Although the circuit acted as a power-interruption detector, when you add a few components, the operating principle lends itself to measurement applications. This ...
    23-11-2022
39. Impedance Transformer Flags Failed Fuse
    Circuits Supply Analog Devices AD8606
    .. into the dc bus. Capacitor C 3 couples the oscillating signal to IC 2 , a gain-of-3 amplifier, which in turn drives a peak detector formed by D 3 and C 5 . Transistor Q 1 saturates and provides a logic-low signal to an external alarm. ...
    18-11-2022
40. Use a heated diode as a flow sensor
    Circuits Measurement Texas Instruments LM393
    .. methods of heating the diode so that the cool air comes in more contact with the diode surface and leads. Thin wire from a metal wire resistor is an easily available material for the diode-heater coil (Figure 3). Reference Raju Baddi, ...
    11-11-2022

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