Lightning arrester installation

Recently I build my new house near Maharagama town. While building this house I allocate space for my antennas and observation equipment. Before installing antennas, I decided to install a lightning rod into the house. The main reason to install a lightning rod is because of the height of the building. It nearly 48 feet (approximately 15m) high, and located in open space, because of those reasons there is a very high probability to hit lightning into my antennas and other equipment.

Installed lightning rod

At the time of this writing, in here in Sri Lanka mainly two types of lightning arrestor systems are in use. The first type is a conventional lightning rod. This type of lightning rod is very common in Sri Lanka and it made with copper rods. The second type is ESE (Early Streamer Emission) type lighting arrestor. This ESE type is now getting popular in here and I saw it in a couple of new buildings. As I noticed most of the lightning arrestor installation companies are now moving into this ESE type solutions.

After reviewing lighting rods in the market, I decided to move into the conventional light rod. The main reason to select conventional light rod is because of its cost. Based on my findings decent quality ESE type lightning arrester costs around LKR 70,000 - LKR 120,000. Again this price further varies with its effective range. The conventional lightning rod costs LKR 9000 only. Also, the effectiveness of ESE type is still in debate. By considering everything I decided to stick to the low-cost conventional method.

Components of the lightning rod.

The next important thing about lightning rod installation is a grounding technique. To find out suitable grounding technique I measure ground resistance using ground resistance tester. After calculating everything I decided to use 25mm × 2.5mm copper tape as my ground conductor and 600mm × 600mm copper plate as a ground terminator.

Copper-tape which we used as a ground conductor.

I bought everything mention in here from a local electric shop. Considering all the components, most expensive items in this system are copper tape and copper plate.

The most painful part of this job is to install a ground conductor in the wall. Due to higher gauge and weight of the copper tape, it took an entire day to install ground conductor.

Support structure which we installed to place ground conductor to the wall.

Another view of the support structure.

After ground conductor installation, the next important task is digging a hole to install ground terminator. The dimension of the opening which we dig is 1.5m × 1.5m and nearly 3m in depth. To ensure lower resistance we combine copper earth-rod into the copper plate and install it inside the hole. Before closing the opening we pour nearly 50 kg of Bentonite powder mixture into it. Bentonite powder is maintenance free, commonly available, ground enhancement material and in here it ensures reliable conductivity between ground and copper plate/tape.

Ground connection layout.

Copper-plate installation with Bentonite mixture.

To fix lighting arrestor I build a structure using metal plates and tubes. The CAD drawing of the structure is available here.

Ground conductor after the installation.

It took nearly 3 days to install this lightning rod and finally now it's in service.

CD2003 - yet another simple FM radio receiver

In the last few days, we are looking for some simple FM radio receiver to integrate into one of our ongoing projects. For that, we try several FM radio receiver ICs including TDA7000, CD2003/TA2003/TA8164, CXA1019, and KA22429. Out of all those chips we select CD2003 (or TA2003/TA8164) based receiver for our project because of its simplicity and outstanding performance. Except to CD2003, Sony CXA1019 also perform well but we drop it because of its higher component count. We design our receiver based on Toshiba TA2003 datasheet and later we try TA8164 and CD2003 with the same circuit. Either CD2003 or TA8164 can directly replace TA2003 IC, and as per our observations, TA8164 gives excellent results out of those 3 chips. A prototype version of CD2003 FM radio receiver The PCB design and schematic which we used in our prototype project are available to download at google drive (including pin-outs of crystal filters and inductors ). Except for CD2003 IC, this receiver consist...

Arduino superheterodyne receiver

In this project, we extend the shortwave superheterodyne receiver we developed a few years ago . Like the previous design, this receiver operates on the traditional superheterodyne principle. In this upgrade, we enhanced the local oscillator with Si5351 clock generator module and Arduino control circuit. Compared to the old design, this new receiver uses an improved version of an intermediate frequency amplifier with 3 I.F transformers. In this new design, we divide this receiver into several blocks, which include, mixer with a detector, a local oscillator, and an I.F amplifier. The I.F amplifier builds into one PCB. The filter stage, mixer, and detector stages place in another PCB. Prototype version of 455kHz I.F amplifier. In this prototype build, the Si5351 clock generator drives using an Arduino Uno board. With the given sketch, the user can tune and switch the shortwave meter bands using a rotary encoder. The supplied sketch support clock generation from 5205kHz (tuner f...

Experimental narrowband FM receiver for 2-meter band

This project is about MC3362 and ADF4351 based modularized, 2-meter narrow band FM receiver. In this design, the receiver splits into three modules as RF preamplifier, MC3362 tuner, and ADF4351 oscillator. The RF preamplifier builts around BF900 dual-gate MOSFET. The tuner stage builts using the popular MC3362 , low power narrowband FM receiver IC. For the oscillator, we use the ADF4351 DDS RF signal generator module. The core component of this receiver is MC3362 IC. This IC was designed by Motorola and is no longer in production, but this IC is still available to purchase in many online stores . The chip we used in this receiver was purchased from a local electronic component store for LKR 75 (USD 0.2). The RF preamplifier used in this receiver extracts from the N.Ganesan's (VU3GEK) LRR200, 2-meter band FM receiver project . Prototype version of the RF preamplifier. In this prototype, the above preamplifier was built as a module using a Manhattan construction technique. Th...

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