Lightning Detectors

The following circuit is an improved version of my original Lightning Detector designed to run on a 5 volt supply. The new circuit features a superior RF section with a single resonance near 300kHz and plenty of sensitivity. The potentiometer was eliminated; simply adjusting the length of the telescopic antenna will give the desired sensitivity. T
Lightning Detectors - schematic

he circuit supply voltage was increased to 5 volts to allow the use of commonly available molded power supplies instead of batteries. Another not-so-obvious feature is that I have plenty of the inductors! (For inductors email charles@wenzel. com. ) The basic receiver is shown below. The antenna is a telescopic antenna that extends to two or three feet, the length is not critical. A high-value resistor (270k) is connected from the antenna to ground to control the Q and this value may be lowered if the circuit seems unstable but too low a value will destroy the sensitivity. The 10 mH and 1 mH ( not uH) chokes are molded types but most moderately high-Q inductors will work fine and the rest of the parts are run-of-the-mill and not particularly critical. The transistors are all general-purpose types. Note: This circuit is intended to be used with one of the lamp options and any or all of the other options. If no lamp is desired, add a 1 k resistor from the "pulses" output to 5 VDC. Below is an experimental version with an additional diode across the 82k. The diode helps the flasher to trigger on smaller pulses. the 82k may be 100k, if desired. The antenna, 10 pF capacitor, and the two inductors form a resonant tank at about 300 kHz, a good frequency for receiving energy from lightning. The two series inductors act as a matching network, feeding Q1 with a lower impedance version of the signal received by the antenna. The 270k...

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