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lightning detector circuit schematic

Lightning Detector Circuit

This DIY lightning detector circuit is a very sensitive static electricity detector that can provide an early warning of approaching storms from inter-cloud discharge well before an earth-to-sky return strike takes place. An aerial (antenna) formed of a short length of wire detects storms within a two mile radius.

The circuit emits an audible warning tone from a piezo buzzer, or flashes an LED for each discharge detected, giving you advance warning of impendig storms so that precautions may be observed.

The primary feature in the lighting detector is the circuit’s ability to be set close to self-oscillation, with its relaxation optimised via the bias resistor values shown in the circuit diagram. The oscillator is dc coupled and feedback is routed through the collector of TR1 to the base of TR2, while the overall loop gain is set with the multiturn(12, 18 or 22) preset VR1.

Setting up the lightning detector

To set up the lightning sensor, adjust preset VR1 for oscillation by monitoring test point TP1, which should be at roughly 7volts peak-to-peak. Test point TP2 should be at +6V dc. Now readjust VR1 back slightly to stop oscillation; use a screwdriver to touch the aerial-side of C1 several times; the alarm should sound for 1 or 2 seconds then stop. If it continues, make a very small adjustment back and recheck. The other method is to electrostatically charge a plastic ruler and then draw your finger close to discharge, about two meter away from the aerial.

Schematic of lightning detector circuit

lightning detector circuit schematic

Powered from a 9 volts battery the circuit consumes about 600 µA in standby. Powered continously it could provide a good year of uninterrupted monitoring. When sounding the alarm, the current will rise to 4mA depending on the low current sounder WD1. A minimum 3 volts device is required for a good output level and it will produce a “pinging” alarm to warn in real time of any electrostatic pulse activity.

42 Comments

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  • wasantha

    I did’t connect collector pin of transistor 1 and capacitor 1 (C1) are there any connection in this circuit

    • ian

      CAPACITOR 1 CONNECT FROM ANTENER TO BASE OF TRANSISTER.
      AND COLLECTOR CONNECT TO RESISTOR R2=330K

  • wasantha

    i used same electronic components as you mention including bc109

  • wasantha

    I bild this lightning detector but it dosn’t work.buzzer never make noise I have less than 1volt voltage on the TP1 or T2. Could you please help me ?

  • ian

    I have build this circuit, glad to say mine does work, but goes off at any time, not sure if it’s picking up static close by as I live in a small block of flats, lights, mobile phone, fridge, and a number of other things could set it off, but it do work.

    • ian

      THIS IS MY END RESULTS OF THE LIGHTING DETECTOR, IT STILL WORK EVEN AFTER MOVING IT FROM THE BREADBOARD, I USE A ZEROSTAT GUN TO TEST MY PROJECT EVEN WITH A FLAT BATTERY IT STILL WORKS, I USE THE ZEROSTAT GUN ABOUT A FEET AWAY AND IT SET IT OFF.

  • roy

    Does anyone have a working mod???? Pls send your schematic and part list..thanks

  • roy

    Hey, I built the circuit but its not working. The buzzer wont stop buzzing. . Help!!

  • Riccardo

    Will a BC109B transistor work?

    from the datasheet the Hfe Typical for the B is 290 where the C is 520

  • SM7I

    Hi, I have the exact same problem as OH8EFI. Have you thought about a solution for that ?

  • Bashka

    What is the value of C4? 4n7 looks like a typo.

  • OH8EFI

    I have built this thing, but it just keeps beeping! Only way to shut it down, is touch TR2 and TR3 with fingers. What to do to fix this thing?
    Thanks.

    • Jim Keith

      Appears that the oscillator section does not stop oscillation properly–should get shocked into oscillation only by a lightning strike. Will think about it for a while–what is the best way to reduce the gain?

    • OH8EFI

      I’ll do that, but I can see the difference clearly when I go to RF clean areas and then go to my house. But even when you don’t have any distractions near-by, it still keeps beeping.. And like I said, only way to silent it is to touch two of transistors, and sometimes it requires even to touch all of three transistors and keep touching for several seconds and then carefully take of your fingers. And then when I trigger it, no matter was it with radio transmitter, spark or touching the antenna, it just keeps beeping..
      Oh, and thanks for rapid answer, I wasn’t expecting any answers with in half a week 😀

    • Jim Keith

      You may be picking up RF from a nearby transmitter. To reduce sensitivity, reduce the value of R1.

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