Electronics

NEMTEK REMOTE CONTROL

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#82 Remote control and monitoring NEMTEK LCD18

During summer there’s been a ton of rain this year and my electric fence alarm keeps going off
The 2 main reasons are lots of water and crazy grass growth around the property.
It’s been impossible to use weed killer because it rains so often it’s all just washed away.

So I decided to install a remote switch as well as a sensor to alert me if the siren is blaring off.

For the switch I used a SONOF RE5V1C DC powered relay. This device costs under R100.00 and can be powered by 5v DC, the switch can handle 10A of DC or SV loads up to 240V.

SONOF RE5V1C

For the alarm siren sensor I used an SONOFF DW2 Wi-Fi wireless door/window sensor. I de-soldered the magnetic switch and just soldered 2 wires to the pads. Now when the siren goes off a 12v relay will close the relay and the DW2 will report a closed event. The DW2 cost R115.00

SONOFF DW2 Wi-Fi

The great thing about this project is the price and the usage of the SONOFF software and MQTT service. There is no need to create my own firmware or MQTT software by using these affordable SONOFF products.

Electronics, Experimental

CREATING A DIY RELAY

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#81 Building a 12v relay on a cheap PCB board

Completed relay

While working on one of my projects I needed a 12v relay unfortunately I did not have one on hand and was not about to pay for 1 relay plus shipping.

Luckily I had all the components at hand:

1 green and 1 red led
2x 470 ohm resistors
1x 1k resistor
1x 1N4007 diode
1x bc547 transistor
1x 12v relay
Some solid alarm wire
Very cheap rectangular PCB

For a 5 volt version just replace with a 5v relay and 2x 100 ohm resistors for the LEDs.

Unfortunately the PCB I had was very cheap and I could not fit the screw terminals I had so I had to squeeze them in.
I also used thin alarm wire as i did not need to switch high amps but luckily everything worked out in the end.

It was a bit messy but next time I will use a better quality PCB that doesn’t burn tracks when making solder bridge tracks.

The BC547 also allows switching with 3.3 volt logic but remember to supply the 12v

Back End, Front End, Laravel, Programming, Server Install

LARAVEL WINDOWS SETUP

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#80 Laravel setup on Windows systems.

One of the best scalable and flexible back-end frameworks for PHP is the Laravel system. This system offers user front-end and an admin panel, APIs can also be written with authentication and many so called “blade” templates are available for purchase or you can make your own front-end.

The walk-through setup files and README.md documentation is available on my GitHub here.

Server Install

INVENTORY MANAGEMENT

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#79 Top free inventory management systems

On my journey working with electronic parts of all kinds. i find myself trying to keep track of all the parts I have in my possession and the parts I still want to buy. My go to method of record is a daily diary entry written on paper but this method has become cumbersome and I can’t search a diary for a specific word in a few seconds…

So I began looking for an open source inventory system where i could record all my components + other things if need be. Bellow is the list of the 5 most promising solutions I could find so far.

Velocidex

InvenTree

PartKeepr

OpenBoxes

ESP32, Experimental

LORA SETUP

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#78 Setting up the LoRa T-Beam

Living on a farm I often encounter communication issues coupled with the urgency to communicate when catastrophes strike. Therefore in my quest to find suitable backups and backups to the backups I stumbled upon the LoRa system. Specifically the LoRa boards in the T-Beam configuration using the Meshtastic firmware + Android app which allows text message communication over a few kilometers in my case.

After testing them I came to the conclusion that they do work and reliability, however they can get damaged easily and the quality of boards and components used is not up to the bar of commercial motherboards such as gigabyte PC motherboards as an example.

My final opinion being: they work and I would use them as one of my “coms” layers however I would not put the T-Beam on par with a mobile phone the quality is simply just not there.

Arduino, Bluetooth, ESP32, Experimental

ESP32 DEVKIT V1

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#76 ESP32 that is Arduino & MicroPython Compatible

ESP-WROOM-32 32-bit 240 MHz microprocessor

The ESP32 has already integrated an antenna and RF balun, power amplifier, low-noise amplifiers, filters, and power management module. The entire solution takes up the least amount of printed circuit board area. This board is used with 2.4 GHz dual-mode Wi-Fi and Bluetooth chips by TSMC 40nm low power technology, power and RF properties best, which is safe, reliable, and scale-able to a variety of applications.

Bluetooth, Electronics, Experimental

JDY-30 BT RELAY

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#75 JDY-30 Bluetooth relay board

JDY-30 Bluetooth

This is a 12V relay that you can switch using the built-in JDY-30 Bluetooth slave module. By using the iq-blue terminal app on your phone, you can wireless open or close the relay by sending simple hexadecimal code to the board.

  1. Provide 12V DC input power to the board
  2. Search for bluetooth device and pair to “JDY-30” (password is “1234”)
  3. Download the IQ-BLue Bluetooth Terminal App
  4. Using hexadecimal, send “A00101A2” (open the relay), “A00100A1” (close the relay)
Back of the board
Schematic
Datasheet
BK3231
Experimental, RaspberryPI

IO PINS ON PI ZERO W

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#74 Operating IO pins on the Raspberry PI Zero W

RaspberryPI Zero W pinout.

While Java programming I started to wonder if I could program a pi board with java. During my research I found out that it is possible and there is the Java ME version that is specifically designed to be used in embedded devices.

Java ME requires the creation of MIDlets which is quite complicated so I decided to start by using the Java SE version and the WiringPi library. I’m using a Raspberry Pi Zero W with DietPi installed.

STEPS

Make sure Java & the WiringPi library is installed on your DietPi.
Now open the dietpi-launcher.

sudo dietpi-launcher

Install Optimized Software > Browse Software > Java

Install Optimized Software > Browse Software > WiringPi

Setting up the APP
Compile the app with Eclipse.
Now build the .class files into a .jar file on windows.
This makes one .jar file and compresses it for easy distribution.
Make sure JavaSE1.8 is selected in Eclipse so that it can run on the PI’s openjdk version "1.8.0_212".

"C:\Program Files\Java\jdk-16.0.2\bin\jar" cvfm GPIOPinTestMain.jar manifest.txt GPIOPinTestMain.class

N.B The manifest file must have an open newline at the end!

Once the .jar file is created you can now upload it to the PI’s usr dir e.g "/usr/bin/a_java_app/gpiotest"

Install OPENSSH to allow Putty connections.

INSTALL ProFTPD so allow sftp://10.0.0.17 connections.

Download the code below

GPIOPinTestDownload

Experimental, Programming

CURSOR ON TARGET

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#73 Cursor On Target (COT) protocol

Example flow

Cursor on Target is a simple exchange standard that is used to share information about targets. Its loosely coupled design led to multiple implementations and is used to facilitate interoperability of several systems with already fielded military software. Cursor on Target was originally developed by MITRE in 2002 in support of the U.S. Air Force Electronic Systems Center. Mitre first demonstrated Cursor on Target during a combined joint task force exercise in 2003, during which a Predator unmanned aircraft was able to operate in coordination with manned aircraft.

COT text example

For more detailed info read this and this document.

The COT protocol is used with ATAK to provide an exchange between sensors + coms etc.

Message-Router-Users-Guide
Data-Schemas-for-Net-Centric-Situational-Awareness
The-Developers-Guide
Cursor-on-Target-and-the-Air-Defense-Environment
Cursor-On-Target-Dr.-Christopher-Niessen

Passionate about technology!

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