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.
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
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.
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
While living on the farm I couldn’t help but notice the necessity of a welder. From fixing gates to fixing vehicles and setting up fences. Creating burglar guards and security gates. These are all musts especially in the dangerous rural areas in South Africa.
So I endeavored on my welding journey, looking for the best welder for a beginner. After months of research I decided on the MAC AFRIC 180 A IGBT (MIG & MMA) Industrial welding machine. It has (120A=100%, 150A=60%, 180A=35% ) duty cycles.
While working with electronics one of the easiest PCB boards I have found to work with is the horizontal stripboard. When using this type of board it is important to cut the tracks in a reliable fashion with adequate clearance veroboard cutting tool by Vero. This is a staple tool in the art of PCB prototyping but… it can be unnecessarily expensive. So I created a simple DIY version.
Here is a small explanation of the process. Also take a look at this link which explains which are the best drill bits for a DIY veroboard trace cutter.
Use a broom handle (or soft wood in a cylindrical shape) a 3.5mm drill bit and some epoxy.
In my case the price was 86.4% cheaper then buying one from the shop in South Africa.
Sometimes an Arduino pro mini is just not small enough for an electronics project. Enter the Arduino ATTINY85, this MCU comes in an extremely small package. It has only 8 pins and works with 5v.
Below are the specs of this microcontroller:
AVR MCU, 8K FLASH, 512B RAM, SPI
Controller Family/Series:AVR Tiny
No. of I/O’s:6
Program Memory Size:8KB
EEPROM Memory Size:512Byte
RAM Memory Size:512Byte
CPU Speed: 8/16 MHz internal clock, up to 20MHz external clock
No. of Timers:2
No. of PWM Channels:4
Digital IC Case Style:DIP
Supply Voltage Range:2.7V to 5.5V
Operating Temperature Range:-40°C to +85°C
No. of Pins:8
This is great and all but its a hassle to program the board unless you buy a dedicated programmer (expensive in SA) or if you’re happy to use a messy breadboard every time you want to program. So I decided to make a very crude but effective programming shield for my Arduino UNO.