[chbot] Robotics Group meeting, 5 Idris Rd, 6-30pm, Monday 20 Mar 2022

Mark Atherton markaren1 at xtra.co.nz
Mon Mar 21 08:44:12 GMT 2022

Hello everyone,

Second Robotics Group meeting under traffic-light red.

Good turnout with 22 attendees, and lots of huddles-of tech-talk. $33 + 
change (in gold, and flat-money) collected and transferred into the 
robotics loose-change jar (for later banking).

All sales from the trading table should go into the brown box on the 
wall, and are directly for the benefit of our host club, Christchurch 
Amateur Radio Club, NZART Branch 05.

Equipment donations are welcome for the trading table, but no CRT based 
product, printers, toner or items that are likely to be a disposal burden.

With thanks on behalf of the group,

Mark Atherton


Mark started off by talking about Redzone Drone Racing Inc, a group who 
apparently meet at 5 Rebecca Ave in their club-room which is a powered 
container, on rented land. Needs more investigation.

Mark also discussed progress on the Electron Gun. The original suite of 
experiments was almost completed when the first (of 10) 75u tungsten 
filaments blew. Upon disassembly, filament current appeared to be too 
high due to the re-use of an original and non-optimum Wehnelt to Focus 
electrode electron feed assembly. Replacing the filament was quite 
painful process, so it was decided to rebuild the whole Electron Gun 

The Mark-2 EG is based on the original design, with mechanical 
extensions using 4mm glass (instead of ceramic) supports. The EG will 
sit on a stable glass and mica tripod assembly. The Mark 3 EG was also 
considered. This is a ground-up design based on more readily available 
5mm glass, with the electrodes fabricated from water-cut sheet brass. 
This is very much in the planning stage.

Robin gave a presentation about passing binary data over a serial link, 
using various protocols including SLIP etc.

Charlie, a student from Cashmere High School made a presentation about 
his teams work on a complex remote imaging project monitoring coral-reef 
health, or more to the point shrimp-farming, which a major source of 
ecological damage to coral-reefs. Image processing was executed using 
(amongst other things) a neural network on a super-computer. Results 
appear to be excellent.

William talked about his processor-controlled mini-spotlight project. 
Latest addition is adding mechanical tilt within the enclosure a 
model-control servo.

Bevin talked about an issue with an Uninterruptible Power Supply. Main 
points of interest were design issues like wrongly placed power switch, 
a faulty battery, and an annoying beep that could not be disabled.

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