You need a Pin Vice (or vise if you're across the pond and want to butcher the Queen's King's English)...
@OldSurferDude said in Some"ting" interesting...:
@NeverDie Non-internet connected networks still need NTP. I built an NTP server from a $5 gps module, a $3 Arduino nano, a $6 ethernet shield, network cable and a USB cable. A neighbor 3D printed an enclosure for me in exchange for 4 home baked cookies (they're awesome). Just for fun, I put in software for an under $2 display to make a clock.
Should we re-title this thread, "Be Afraid, and here's how to ameliorate your fear. "
In the scenario I was referring to, the IOT devices are still internet connected. They're just on their own dedicated local LAN (which could be a virtual LAN), that's all. Now, shutting them off from the internet entirely.... maybe that's another step one could take, depending on what it is. I have some lights/switches that were cheap but which have to run through the cloud in order to connect with Alexa. They wouldn't work properly if they were cut off from the internet.
@NeverDie That isn't what I was thinking but after a bit of research, that's better than what I was thinking.
PCB antennae work better at > 868MHz(pg 7). A 2.4GHz signal should have an antenna length of 3.1cm The nRFl01 spec shows a PCB with an antenna that is about that length but I measure the board I have and the antenna is about 4.6cm(?) Here(pg 10) you'll find a design, though I'm not sure for what frequency as the length adds up to 4.03cm. As you can see, you must not have the ground plane near the antenna.
Here, RonM9 modifies an nRF24l01 making the antenna a dipole. I tried this and did show some improvement, but not the success he had. His wires were ~5.0cm, but bends them in the opposite directions at the edge of the pcb. Does that make the antenna length about 4cm?
The antenna for a longer wave length (lower frequency) will be proportionally longer.
I'd like to do the same testing as RonM9, but I've got some other pressing projects.
I hope this helps your research.
@Larson About 10 years ago I did it using the A2D on an Arduino Due once for a simple 433Mhz OOK receiver. It worked well enough. Like you, it was my first experience doing such things. The hardware was so basic that it was a software-only radio from the mac layer up. The Due was fast enough that I could detect both the original signal (shortest path) and subsequent bounced signals (multipath) as separate entities. I still think it's pretty cool.
In a previous house I had a wireless sensor that was cylindrical. I drilled a roughly 3/4" - 7/8" diameter hole in the doorframe and slide it in, so it wasn't at all visible when the door was closed. Because of the packaging and form factor, some exotic things, like that, are far easier to buy than build, though I suppose it would be within the grasp of someone with skills who was determined to make their own.
Less exotic: if you made your sensor flat enough, you could hollow out the door molding and hide it inside of that. A properly designed door sensor could run off of a CR2032 coincell battery for 10+ years, so it's not such a wild idea.
@NeverDie said in Which PCB fab do you currently like the best?:
... a project stalling out for want of a nail...
That is poetic.
I try to have some sympathy for my favorite (OSH_Park) and order multiple boards at once. Some pain of waiting is involved - only a week - and some waste is incurred by me as I correct my own errors before they ship. But I do like that they only ship three boards, instead of five, when I only need one. They must be annoyed by little-guys like me so I try to do my part with loyalty.