A basic detector radio set that uses a vacuum tube instead of a crystal detector. This radio requires few components, and because it`s inherent simplicity it is easy to build. In spite it`s simplicity this receiver performs well if a high-strung long wire, well-insulated antenna is available, or strong stations are nearby. A short-w
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ave version works great almost everywhere whenever wave propagation is good. Parts list for this simple vacuum tube detector radio: B1 - 1. 5 Volt Dry Cell C1 - Rotary Capacitor - 500 pF (pico Farad) C2 - Filter Capacitor - 1 nF, used with magnetic phones only D1 - Diode - Diode, Vacuum Tube Detector L1 - Antenna coil - 75 turns 180 uH (micro Henry) R1 - Load resistor - 200 K, used with crystal phones only Coil L1 on Picture 1 is hand wound in a universal style to reduce coil capacitance. It is wound on a 1/4-inch diameter coil form, outfitted with a good (low loss) RF ferrite tuning screw. The antenna coil L1 is 75 turns preferably with 10x0. 05 MM Litz wire, with taps at 15, 30 and 45 turns. These taps marked 2 and 3 on the schematic diagram, and they are useful for improved impedance matching. Coil inductance need to be around 200 uH with a 500-pF C1 capacitor Litz wire is a specially insulated multi-strand RF magnet wire; it has 10 strands, each 0. 05-millimeter diameter. The more conductors a Litz wire has the better. With smaller wire size, it gets progressively harder to remove the enamel from all the tiny strands for soldering. There are several commercial preparations available for just such purpose, they works well if not exactly fast. Litz wire with low temperature insulation can be tinned directly, as the enamel melts off during soldering. Since multi-strand wire increases the wire`s surface area, it helps to...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
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In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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