Notes from the Electronics SIG Zoom meeting 9 January 2025
Six members attended
Vern Ehlke, Tom Alexander, Graeme Dunbar, Stephen Rainsbury and Hugh Norwood
Tom has been planning a model of the restored Brighton Belle, which will require sub-miniature multiway conducting couplings – or possibly a decoder at both ends. There are some 1.25mm pitch connectors available which might suffice.
Jeffrey is continuing his research into ESP's and looking into controlling layout lights – both overhead and internal, to cycle through a 24 hour period in about an hour. He is also building a DCCX controller.
Verne has a dual gauge test track and has been learning KiCad to use it to create a unit that will allow any of four inputs (DCC, DC, etc) to control either of the two tracks.
Stephen has been looking at a Pi based DCC controller; it is £15.20, but it is a tad big, at 25x20mm, for 009. Still, it would be attractive to some.
Graeme has repaired a Christmas tree animation that has a couple of trains on it. He has been looking at ways to updated his Pizza layout with some sort of sensor, so that it activates when someone comes into view. Options include PIR and a small device that appears to use microwaves(!) - (this from PiHut). The Glasgow show (Model Rail Scotland) is coming up, which provides extra incentive. He is also looking into using Dapol 4mm scale platform signals, being shorter than the normal ones.
Hugh reported that following the trip to Amberley Museum in October with Angst-Lesspork, when he saw working scale model semaphore displays, he revisited his own efforts (the Clacks on the layout is loosely based on the Murray system). He has been dabbling in the Dark Arts of Javascript to create and interactive display within a Web page. He showed the results. He used the W3schools web site for inspiration on coding, and leant on his son for help finding why it didn't work at first.
The page can be found here
Semaphore Demonstration (http://hnorwood.co.uk/files/semaphoretest.htm)
semaphore_screen.jpg
Screenshot of demonstration
There was discussion on whether ultrasound could be used to locate trains on a layout (rather than use, say, occupancy detection). It appears Faller make something – at a price.
The next meeting will be on 27 February (and not 13 Feb as discussed)
HN 22 Jan 2025
Thanks for the summary Hugh!
This is the microwave Doppler sensor referred to:
https://thepihut.com/products/microwave-motion-sensor-rcwl-0516 (https://thepihut.com/products/microwave-motion-sensor-rcwl-0516)
I bought mine from eBay and got ten ( !!!! ) of them. The reason being that I wanted at least two and the cost of the ten (including postage) was only a pound more than one from the Pi Hut and two from them would be rather more than my eBay purchase.
https://www.ebay.co.uk/itm/126131048917 (https://www.ebay.co.uk/itm/126131048917)
I was a little concerned that they might not work but the ones I've tried do - plus it was my lucky day and I got a decimal bakers dozen.
They seem to be quite sensitive - I was able to trigger one from one bedroom across the hallway to the other bedroom. It appears that it is possible to 'shield' them to prevent triggering from unwanted directions. I've yet to find out how much I can control that. Another thing I want to try is to see if two sensors interact/conflict.
Here is a fairly comprehensive explanation of how they work:
Edit: hmm, apparently they do not interact which is a good thing if I want to trigger different animations:
A layer of wax might attenuate the microwaves. I seem to recall wax lenses being used for microwave experiments way back in my undergrad days...
Quote from: Hugh Norwood on January 22, 2025, 20:30A layer of wax might attenuate the microwaves. I seem to recall wax lenses being used for microwave experiments way back in my undergrad days...
I seem to remember something said about pouring or melting wax in waveguides and letting it harden at an angle so there was a wedge of the stuff at the end of a stub but I may be mis-remembering. It it certainly used for lenses.
https://digital-library.theiet.org/doi/full/10.1049/iet-map.2015.0667 (https://digital-library.theiet.org/doi/full/10.1049/iet-map.2015.0667)