[Makerspace] Projects eShow and Tell?

Felix Sheldon darkpaw at internode.on.net
Sun Mar 17 12:34:07 AEDT 2019


Thanks Greg,

Good idea, yep!

Could you explain why it's hooked up that way? Is it to bring the signal
from the first antenna in there for measurement?

-------------------------------------------------------------------------------------------------------------

The project I'm working on currently also needs radio, but only short
range, and so I think I will just use Wi-Fi.

The project is a timing system for Flyball:

https://en.wikipedia.org/wiki/Flyball

I'm starting with the "start lights" which count down to the race start
with 5 LEDs - Red, Orange, Orange, Orange, Green.

It should be possible to get those to work with an existing commercial
timing system which does not provide the start lights. That system uses the
915 MHz band with little packet radio chips like this:

https://core-electronics.com.au/sparkfun-rfm69-breakout-915mhz.html

But the plan is to later do all the other parts as well, and use WiFi
instead.

I'm going to build a series of prototypes to get the design to a point
where it's reliable, tested and fairly easy to make.

The main parts are currently:

 - The Onion Omega2, which is basically a WiFi router chip running OpenWRT

     https://onion.io/omega2/ -
https://docs.onion.io/omega2-docs/omega2p.html

 - Some 3W LEDs - should be visible in any conditions.

 - MOSFETs to switch the LEDs.

 - 4 x 18650 Li-ion batteries and some protection modules from Ebay.

-  3D printed modules to mount all the other bits and allow them to fit
inside:

-  A 65 mm acrylic tube for weatherproofing

I'm not real sure though that I should have used lithium batteries, due to
the safety risk, but they are just so good!

A couple things I'm considering to avoid mistreatment of the batteries are:

 - Put the batteries in a sealed 3D printed module and then make a matching
charger from an existing commercial one.
 - Don't add an off switch so that the users are forced to remove the
batteries after use. Maybe beep annoyingly after inactivity.
 - Take apart a commercial charger and build it into the project.

But after sorting all that, and building the next components, I'm pretty
much left with a software project to do all the hard work.

I'll just keep it simple and use TCP/IP for all the parts to talk to each
other, and write a cross platform control software that can run on laptops
or tablets.

There's a great UI library for Python:

https://kivy.org/#home

And this project can synchronise clocks:

https://chrony.tuxfamily.org/


Some photos:

[image: IMG_20190310_125748.jpg]
[image: IMG_20190317_120626.jpg]
[image: IMG_20190317_120642.jpg]
[image: IMG_20190317_120718.jpg]
[image: IMG_20190317_120832.jpg]


On Sat, 16 Mar 2019 at 13:44, Greg Hall <greghall at brushbox.info> wrote:

> Makers,
>
> I think it would be good to send short summaries of the projects that we
> are working on, thinking about or could use some help on, to the list.
>
> That way, we could identify topics for presentations, find common interest
> groups, and give some of those stalled projects that we all have gathering
> dust a boost.
>
> -
>
> To kick off, I'm attaching a couple of photos, a spreadsheet and a
> screenshot of an antenna experiment that I did last year.
>
> Inspired by a friend in a hospice who needed connectivity (even though the
> place was buzzing with it's own networks), and the ridiculous price of
> ready-made antennae:-
>
> I made two Bowtie antennae for 850MHz, placed one inside an 'RF proof'
> clothes dryer tub with wire mesh both ends, and connected it to the other
> up a bamboo pole, pointing at our new Telstra mobile phone tower.
>
> To get an idea of the system gain (albeit loosely coupled to my mobile
> phone), I sat the phone on a slab of Styrofoam above the 'shielded'
> antenna, and used an Android app 'Network Cell Info (lite)'.
>
> The RSSI shows that I has getting ~6dB gain overall. I've since bought the
> https://www.analog.com/media/en/technical-documentation/data-sheets/ad8307.pdf
> and will apply myself to getting some actual measurements;)
>
> -
>
> Greg Hall
> 0265504481
> 0428850144
> -
>
> On 15/3/19 6:36 pm, Felix Sheldon wrote:
>
> Hi all,
>
> Does anyone have any suggestions for a talk or demo at the March meeting,
> probably Wed 27th? I'll create a Meetup event in the next couple of days.
>
> Here's a Discord invite again too:
>
> https://discord.gg/pHAVsMm
>
>
>
>
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