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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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  • Bashka

    I have a question about R5 in the LED section. Is it just a current limiting resistor? And if so, shouldn’t it be rather 330 than 33k? At 9V and 33k current is limited to 0.2 mA, which seems to me way to low to light a standard LED rated 20 mA.

  • imanbikugmail-com

    Sir is this circuit works really?

  • Jeroen van Bergen

    It works very nice. I’m using it with a 2S LiPo (i.e. 7.4V nominal) as power supply and works like charm. I use it to capture lightning strikes. I’ve added an opto-coupler that connects to a DSLR. Made a small PCB of it, the final version was molded into epoxy resin.

    • imanbikugmail-com

      Sir is this circuit works really well? Can you send me circuit you did sir?

  • Lightning

    Alright, here’s an update on the one I built. I got it to work pretty well. I adjust it by turning the pot until it stops oscillating. Sometimes it does so very slowly, like it will click once every minute consistently, this is because it’s still oscillating. At this point I just start turning very slightly until it goes away and I’ve marked the spot on the pot where it works the best without oscillating but also with good sensitivity. I ended up adding the buzzer too as I realized how inconvenient it is to have to be looking at it to know when it’s doing it’s job.

    Here’s the issue I have with it though, it eats up batteries. I really wish I could leave it on all the time and not have to worry about it but the battery lasts about 3 days tops and after that the battery is down to around 5 or 6V already. When I monitor the current flow nothing seems out of the ordinary though. Any idea what could be causing this?

  • John Murray

    Thanks for the quick reply, Jim. If I eliminate C2, where does the wiper on the pot connect to?

    Thanks
    John

    • John Murray

      Hi Jim

      I have removed C3 and the unit now works just fine! The unit is very sensitive and needs to be housed in a metal case for stability. I have added a 555 latch and LED to record an event when I am not present. This can be cleared with a push-button. Modified circuit attached.

      John

    • Jim Keith

      Woops –I meant all that about C3.

  • John Murray

    Hi Jim

    I have the same problem as OH8EFI. The unit will not stop oscillating (about 30kHz), even with the junction of R1 and C1 grounded. It will stop if I touch my fingers on the cans of Tr1 and Tr2 at the same time. I have carefully checked my construction and component values. All seem OK.

    Any suggestions?

    Thanks John

    • Jim Keith

      Try reducing the value of C2 or perhaps eliminating it –or adding a resistor between it and the emitter of TR2. This is a type of phase shift oscillator and they are known to be flaky. C2 is supposed to introduce the first phase shift, but it is connected between a low impedance point (emitter of TR2) and common –this minimizes the first phase shift.

  • Tom

    Oh, a good question is will this detector detect lightning from further away with a longer, external antenna like a random wire, or will a longer antenna be too sensitive so that it sets it off all the time?

  • Tom

    I’m planning on building a lightning detector and not sure what other schematics I’ve found, but this one looks pretty easy and straightforward to build. I may make two of them, one for my radio shack so I’ll know to unplug antennas, and one to keep in the camper.

  • Lightning

    I built this circuit successfully. I didnt use the buzzer for mine, just the LED. At first I had the same issue where the detector would not turn off but I discovered I had wired the C6 capacitor on the LED incorrectly which is an easy mistake to make and should be checked. Also make sure you didnt accidentally use a code 473 capacitor instead of 472 for C4. After that it would still not turn off until I adjusted the 10K pot. The best way is to turn the pot slowly til it stopes ticking by itself. Dont turn it all the way down as I believe this makes it look sensitivity. Mine is about 7-8% away from being turned all the way down.

    It is also very sensiive to the interference generated by switching power supplies and my computer so this may be the issue for some of you if you have a lot of interference around you.

  • wasantha

    i did the same but didn’t work where is the problem

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