Posts Tagged ‘Electronics’
Meet the Arc Fault Circuit Interrupter
September 13th, 2015 | 
Author: 
You are probably familiar with the Ground Fault Circuit Interrupter (GFCI), also called Ground Fault Interrupter (GFI), Residual-Current Device (RCD) and a few other names. While doing some electrical work for a family member, I discovered Arc Fault Circuit Interrupters (AFCIs) in the breaker box. Having a genuine Electrical Engineering degree (two, actually), I’d like to believe that I am reasonably up to date on basic house wiring. But somehow AFCIs had escaped my attention, even though they started appearing in the National Electric Code over 10 years ago.
A bit of searching on the internet revealed that these newfangled devices are intended to detect arc faults are below the trip level of a normal circuit breaker. Think in terms of a frayed extension cord that arcs over, creating a fire hazard, but not exceeding the 15 ampere rating of a typical house circuit. As usual, the Wikipedia entry is a good place to start. AFCIs detect arcs by monitoring the current behavior throughout the 60 Hz cycle. There are characteristics in the waveform that indicate an arc condition exists, causing the AFCI to disconnect the circuit. This article goes into more technical detail if you are interested:
New Technology for Preventing Residential Electrical Fires: Arc-Fault Circuit Interrupters (AFCIs)
Just like GFIs, AFCIs are available for installation in the main breaker panel and for installation at the electrical outlet. The diagram below shows the block diagram of a typical single-phase AFCI. This is not your old school circuit breaker but a complex system that performs both arc and ground fault detection. As already mentioned, the arc detection is performed by sensing the current behavior. The ground fault detection senses the difference between the current leaving and returning to the device. If there is a significant mismatch between the two currents, a ground fault has occurred.
From “New Technology for Preventing Residential Electrical Fires: Arc-Fault Circuit Interrupters (AFCIs)”
This post is just a quick introduction to AFCIs, with a USA perspective. Your local building codes are now or will soon be requiring AFCIs on new construction, so you’ll probably encounter them sooner or later. The National Electrical Manufacturers Association has a website with additional information: www.afcisafety.org.
73, Bob K0NR
The post Meet the Arc Fault Circuit Interrupter appeared first on The KØNR Radio Site.
Acorn II SDR Kit
This year at the RSGB convention we will be running a buildathon based upon the same format of the other successful build events in the past – this is an excellent time to attract a new audience to our events.
This year however we are using a new kit. The Acorn II kit developed by Kanga Products and M0XPD, is a Software Defined Radio kit that runs on the SSB portion of 40m. But the kit can also be configured to run on any HF band – assuming you have a Band pass filter & a suitable Local Oscillator. The kit has been developed to allow you to pipe in an external Local Oscillator and allow you to connect Band pass filters for other HF bands.
The kit was developed to run with the M0XPD Si5351A Arduino shield, which allows you to use the Arduino as a VFO. And can plug straight into the radio as a local oscillator
Using just a stereo line in on a sound card, and some widely available SDR software (Such as HDSDR), you can get great results from little financial outlay. It is indeed a great introduction into SDR.
I built one of the prototypes here is a video of the build. I will cover configuration & set up in a forthcoming video – perhaps when I have access to a good 40m antenna
Acorn II SDR Kit
This year at the RSGB convention we will be running a buildathon based upon the same format of the other successful build events in the past – this is an excellent time to attract a new audience to our events.
This year however we are using a new kit. The Acorn II kit developed by Kanga Products and M0XPD, is a Software Defined Radio kit that runs on the SSB portion of 40m. But the kit can also be configured to run on any HF band – assuming you have a Band pass filter & a suitable Local Oscillator. The kit has been developed to allow you to pipe in an external Local Oscillator and allow you to connect Band pass filters for other HF bands.
The kit was developed to run with the M0XPD Si5351A Arduino shield, which allows you to use the Arduino as a VFO. And can plug straight into the radio as a local oscillator
Using just a stereo line in on a sound card, and some widely available SDR software (Such as HDSDR), you can get great results from little financial outlay. It is indeed a great introduction into SDR.
I built one of the prototypes here is a video of the build. I will cover configuration & set up in a forthcoming video – perhaps when I have access to a good 40m antenna
Arduino CW decoder – Conclusion
1. Line in or Microphone input
2. Easy to read display – all boxed neatly
3. An LED that shows the Zero beat
4. Easily accessible Reset Switch
5. Powered from a 12v supply.
I did want to create a usable PCB, something that could be used by a student or someone wanting to build the kit. So using the Fritzing application I set about laying out a circuit board.
This was my very first attempt at creating a PCB , so nerves were a wee bit on the tense side. I also wanted to box the project, so my rationale was to find a box first to work out the physical dimensions of the finished project.
As with the Vero Version – I created a layout that would fit on top of the UNO.
After submitting the design, and waiting a week I managed to get hold of 3 boards. They looked awesome. All white and exactly how I laid them out.
I did make 2 small errors on these boards. The first issue was sitting the capacitors a bit too close to the LM567 IC. That is an easy fix for the next version. But the 2nd and more serious issue is I forgot to ground 2 caps. They were floating and in parallel. I did fix this by attaching a wire to ground from one of the caps. That solved the issue, and I have already corrected the fault for the next batch of boards.
2 further observations of the boards & the project as a whole have highlighted 2 further improvements to the project. The location of the pins for the display / reset switch and audio OUT should be on the other side of the board. That would make a far better layout. Also adding in an audio oscillator / switch & plug to insert a key on the oscillator – then feed the output to the Arduino would immediately mean this kit could be used as a practice oscillator too. – that would show the letters as you transmit them out.
So here is a review of the project so far, and what I intend to do with the project going forward.
Arduino CW decoder – Conclusion
1. Line in or Microphone input
2. Easy to read display – all boxed neatly
3. An LED that shows the Zero beat
4. Easily accessible Reset Switch
5. Powered from a 12v supply.
I did want to create a usable PCB, something that could be used by a student or someone wanting to build the kit. So using the Fritzing application I set about laying out a circuit board.
This was my very first attempt at creating a PCB , so nerves were a wee bit on the tense side. I also wanted to box the project, so my rationale was to find a box first to work out the physical dimensions of the finished project.
As with the Vero Version – I created a layout that would fit on top of the UNO.
After submitting the design, and waiting a week I managed to get hold of 3 boards. They looked awesome. All white and exactly how I laid them out.
I did make 2 small errors on these boards. The first issue was sitting the capacitors a bit too close to the LM567 IC. That is an easy fix for the next version. But the 2nd and more serious issue is I forgot to ground 2 caps. They were floating and in parallel. I did fix this by attaching a wire to ground from one of the caps. That solved the issue, and I have already corrected the fault for the next batch of boards.
2 further observations of the boards & the project as a whole have highlighted 2 further improvements to the project. The location of the pins for the display / reset switch and audio OUT should be on the other side of the board. That would make a far better layout. Also adding in an audio oscillator / switch & plug to insert a key on the oscillator – then feed the output to the Arduino would immediately mean this kit could be used as a practice oscillator too. – that would show the letters as you transmit them out.
So here is a review of the project so far, and what I intend to do with the project going forward.
CW decoder – The Arduino
This is arguably the simplest part of the project. As mentioned Budd Churchward had created a series of videos on how he wrote the Sketch, created a PCB and published his code. (Budd’s Sketch is available here)
PIXIE 2 QRP Transceiver build
