I have been playing around with a little electronic project that has been bringing me a lot of fun. I found out about a LIGHTNING DETECTOR designed by Mr. Charles Wenzel - a true genius when it comes to making small VLF gadgets and other medium skill-level doodads. I highly recommend his web site for those curious to learn about some really esoteric electronic doohickeys. Just click on his name to visit his web site. I spent hours there looking at all of the circuits, schematics and pictures. Charles is quick to respond to questions via email. My original reason for researching this device was so that I could disconnect my ham radio antennas whenever lightning was in the area. It works perfect for that application. Once you get used to the way it acts under different weather conditions it becomes even more valuable and a great safety device.

My Prototype #1

ACTION MOVIES ARE THE PROOF OF THE PUDDING

Here are three little movies of the prototype in action on June 15 & 16 - 2007 at my QTH. The first two are 1-minute movies of how the unit behaves. The Boom Box video (recorded on July 14, 2007 at 19:30 CT) runs about 2:46 and shows the lightning meter in action, a little sound from the audio amp section along with a security camera monitor showing lightning flashes in sync with the LED on the detector. Press the BACK button after viewing a movie to return to this page.

"TURN UP YOUR SOUND"

An Approaching Thunderstorm

Heavy Thunderstorm Right Over Me

Boom Box In Action

Here is the whole shebang as it appears with the extended rod antenna. It was built inside of a Radio Shack project box on a little copper clad perfboard. Cost about $12.00.

My New Detector Boom Box

Here are some in-progress, construction photos of my 2nd prototype - and likely my last in this detector series. Charles Wenzel was beyond helpful in providing me advice and parts galore. I couldn't thank him enough for his friendship and guidance.

This unit will include an audio amp so that I can hear the snap, crackle and pop of the VLF emissions of lightning strikes. It will also include a small summing panel meter and the old reliable flashing light switch and LED like the one used on my first prototype. In addition, I will have a simple RF output so that I can run the raw signal into my DATAQ AD amplifier or the sound card on my computer. A free spectrum analyzer software package is available for looking closer at the VLF emissions.

"Front Panel"

"Almost Complete"

"Here it is just before closing it up..."

FULL-TILT-BOOGIE

(Below) I added a little LCD event counter that responds to every other tick of the detector using a flip-flop. This makes it easy to count the actual lightning strikes during an event instead of noisy houshold switches and the like. Since lightning actually creates two (2) large spikes, I used the alternate PNP driver circuit by Wenzel to drive a 2-transistor flip-flop which drives a small reed relay. I can also plug in just about anything that can be switched - like a 7 watt lightbulb or even a surplus Navy fog horn. The red momentary SPST button resets it to 00000. The number currently showing (3351) is NOT from an actual storm but from a cheap dimmer switch which is so noisy that it is a good way for me to test the device.

I am really happy with the results. The "summing meter" is perfect and works flawlessly - the more strikes, the greater the needle movement - and it decays very slowly as the filter discharges. The audio is crisp and clean and I can switch it between the "pulses out" or directly from the collector of the RF amp. The green LED flashing light is just as sensitive as my prototype. I have provided a data port coming from an NPN amplifier fed by the collector of the RF amp. When I use the data port and/or the audio amp, I can switch OFF the flashing light circuit to prevent huge spikes from disrupting the raw RF signal.

If you have an interest in building one of these, plan to visit Charles' web site - TECHLIB.COM.- and be sure to nose around for awhile. Everything you need is presented - including tons of pictures, schematics and construction notes galore. He gave me a package of the hard-to-find chokes used in the VLF tuned front-end and I still have enough for 4 or 5 units. Until I run out, I will be happy to give (as in FREE) a pair of them to anyone who writes me.

I'm thinking about putting on a ferrite antenna in order to try to pinpoint the direction of the greatest energy spikes. I have one in my junk box but my old geezer eyeballs are too worn out to do it now.

73,

K5FNW