Circuits & Schematics: metal detector - 6

51. Power supply +4.25 - 20V/15A and +1.25V - 12V/3A is based on application of National Semiconductor 3 voltage regulators LM338
    Circuits Supply National Semiconductor LM338
    .. and him replace with proportional value constant resistance. The Rectifier Bridge BR1 should be placed in some point of metal box so that it's frozen. On the contrary the IC1-2-3, that good are is TO-3 case, should be placed in a ...
    Apr 10, 2005

52. Simple Fixture Determines Leakage of Capacitors and Semiconductor Switches
    Marián Štofka
    Circuits Measurement Analog Devices AD8661 ADR391
    .. leads terminated with a gold-plated phosphorus-bronze pin can serve as a low-leakage switch. You can find gold-plated metal pieces in any type of high-quality connectors. Also, you can clip the DUT or CUT between two gold-plated clips ...
    Jul 28, 2020

53. Thermocouple Temperature Meter
    Circuits Measurement Microcontrollers Usage
    .. between the two junctions and well proportional to the temperature. There are some type of combination of materials (pure metal or alloy) as industry standard for temperature sensor. The K-type (chromel - alumel) thermocouple is the ...
    Nov 26, 2012
54. Regulated Automotive Switching DC-DC Converter
    Circuits Automotive Supply UC3843
    .. tabs of the transistor and diode to be shorted together.. In other words, you can't simply bolt them both to a single, metal heatsink. In this version, I bolted the transistor to the heatsink, as it is the major heat-generator, and ...
    Oct 16, 2007
55. Cell Phone Controlled Door Latch
    Circuits Security Cellular
    .. and you just have to supply the required voltage to make them work. I simply fastened the solenoid to the door knob with a metal wire. When the solenoid is switched on, its linear motion twists the door knob and opens the door. Positioning ...
    Nov 18, 2007
56. Build It: Hack Your Doorbell
    Circuits Domestic Audio
    .. to the transformer (these notes will help you rebuild your doorbell, if you long for a dingdong, again). Remove the metal plates, electromagnetic coils, and movable plungers from the doorbell. Connect the MP3 speaker and squeeze both ...
    Nov 20, 2007
57. Flash an LED from ac-mains power
    T A Babu
    Circuits Supply Light Fairchild LM317
    .. , part of the passive dropper, limits the current drawn from the power line, as the following equation shows: A 47 Ω metal-oxide resistor, R 1 , acts as an inrush-current limiter. Because the LEDs require a lot of energy, it’s ...
    Jul 26, 2020
58. Water Activated Alarm
    Circuits Domestic Beginners NE555
    .. the collector circuit enabling the 555 osillator to sound. An On/Off switch is provided and remember to use a non-reactive metal for the probe contacts. Gold or silver plated contacts from an old relay may be used, however a cheap ...
    Oct 27, 2007
59. PWM DAC settles in one period of the pulse train
    Jordan Dimitrov
    Circuits Oscillators Microcontrollers Usage Texas Instruments TL071A LF398-N OPA2277. CD74HC02
    .. the R3/R4 ratio is as close as possible to 2:1 and the offset voltages of IC2 and IC4 are as low as possible. R1 and R2 are metal film 1% resistors. C1 is a 2% capacitor with low dielectric absorption. Switch transistor Q1 should have small ...
    May 7, 2020
60. How to Make a Speaker Using a Plastic Cup
    Circuits Audio Beginners
    .. card and not higher than one inch. I used Lego bricks because I had some handy. Wood may work better. Try not to use any metal that can be attracted by the magnet. Put some glue on the magnet when it is inside the cylinder. On this step, ...
    Dec 24, 2007

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