| 2021 | Dec |
 | Most of the past nine months has been spent honing the strategy and architecture of the layout control Python program. With winter I wondered if it is time to move out of the cold loft into what was my son's bedroom. So took the plunge using the electric hoist I installed a few months ago. I was relieved that my design of the 2.5m x 1.4m layout's three modules did (just) fit the hatch. My "new" desk is right next to a window and a radiator! |
| 2021 | Mar |
 | The layout has 27 turnouts. The branch line had 10 working but for the complete layout I now needed a lot of servo assemblies with reed "frog" switches, and electronics to operate them. MERG CBUS CANMIOs had got me started but have their disadvantages, especially when it comes to sets of crossing gates and semaphore signals. So I developed a simple solution with Arduino Nanos and CJMCU-2317 I2C expanders, which will also interface with my Track Current Detectors (TCDs). |
| 2021 | Jan |
 | Finishing the wiring and connecting some traction electronics to get trains running on the mainline provided a specific target. At this point I realised there was another key stage with an "open-frame" layout. There is very little between the rolling stock and the four-foot drop to the floor. Earlier on I had accidentally knocked a loco off the branch line. It survived. I became more careful. Then I watched one of the first trains on the mainline derail at a turnout, trundle a short distance further then (the loco) topple over the edge. It too amazingly survived. So this month has been fitting blackened "fences" to all non-scenic sections and putting some sort of landfill in all scenic areas. |
| 2020 | Nov |
 | Having pretty much decided the solutions to use, I wanted to finish the laying the second half of the track - the link from St Blazey to Par Junction, the GWR mainline through Par and over the viaduct, and the recirculating loops associated with the main line which will be hidden under scenery. This is the overhead "fish-eye" view. All track and servo mounts are installed. Now to install wiring to each track district and to each servo. |
| 2020 | June |
 | Another diversion. I started learning how to put scenery together - in the area of Fowey station. |
| 2020 | May |  | I spent a lot of time on software during the Covid lockdown in April-June. So much that I needed "something completely different". So I experimented with getting semaphore signals to work. |
| 2020 | Feb |
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Having adequately verifed the traction and turnouts solutions I built the whole of the branch line (orange). It has 12 turnouts. 5 of those do not yet have servos, 2 of which are for later linking (blue) to the main line (green). There are 6 quad throttles some of whose outputs power 12 track districts (2 are double-powered reversing loops - red). Additionally 5 subdistricts are powered via turnouts. I planned the final allocation of districts and realised I may need to add another 8x16 mutiplexer and increase the final quantity of throttles from 32 towards 48. I have pcbs for 10 quad throttles, plus the prototype makes 44. This now allows me to move on to debugging the (partial) system and verifying solutions for train-locaters. |
| 2019 | Nov |
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The whole system gradually began to come together with some prototype throttles, a couple of installed Hall effect train locaters and the first few servos operating some turnouts. The method of installing servos went through several evolutionary phases. These have reed switches for switching power to frogs, point blades and, optionally, adjacent track districts.
Once the throttle design was proven I tackled my first PCB designs and ordered 10 off (expecting to use 5) quad throttles and 5 off (expecting to use 2) boards to hold the matrix ICs. Some automated timetrials along a 415mm length of the layout proved the robustness of many aspects of the system. |
| 2019 | Oct |
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First trains run on outer, branch line loop of Par Valley, layout 3. Experimental/practice layout (#2, figure-of-eight) dismantled, some electronics re-used.
An early challenge has been to develop and test a cheap rugged "throttle" (power amplifier) circuit and then PCB. There will be one for each of the 20 or 30 track districts/sections. A new requirement is to handle reversing loops where there is one throttle on each rail instead of having one rail permanently connected to common/0V/ground. On entry to a reversing loop one throttle holds one rail at 0V and the other throttle/rail is, say, +ve. Part way round the loop the electronics switches the first throttle/rail to -ve and the second to 0V - allowing the train to exit the loop without stopping but with the correct rail at 0V. |
| 2019 | June |  |
Layout frames rest on a chest-high trestle in the loft/workshop/office and can pass through the loft hatch. There are two "holes" in the layout, one 5-sided and the other almost square. These could be covered with removable scenery. They provide access to otherwise-unreachable parts of the layout. They are also vital to allow the layout modules to be "threaded" through the loft hatch.
Less than half the track will be visible/scenic and the layers/gradients make "open-frame" construction ideal. The weight of the layout modules therefore remains low. Access to a lot of the electronics, servos & wiring can be from above - avoiding having to crouch underneath and struggle to see through varifocal glasses. Modules can be set on edge or upside-down if necessary. |
| 2019 | Feb |  | Began experimenting with Arduino for superimposing short alternate-direction pulses on the ("DC") traction Voltage. Pulses in general are good at overcoming "stiction". Substantial alternating +ve and -ve pulses can be used even at the slowest speed and when stationary. Experimenting mainly with old "Poole" Farish Diesel locos showed that the (~30Hz) vibration of the (5-pole) motors also helped maintain track contact when "stopped" and can provide appealing sound effects. An Arduino MEGA2560, with its larger 256K program memory, proves much better than analogue circuitry for generating DC-biassed pulse streams for 8 locos simultaneously with independently-variable height, width and frequency, with well-shaped edges to reduce EM radiation (and possibly damage to motors). It is commanded from laptop/Python via USB. |
| 2019 | Jan |  | Began lengthy, detailed 3D design of 1.4m x 2.5m open-frame, 3-module layout. In the centre is Par, Cornwall, much as it is today, on the main line from Plymouth to Penzance. A mere 440m Northwest is St Blazey (formerly St Blaise) where the two derelict platforms can still be seen on what was the Cornwall Mineral Railway which replaced the canalised Par River bringing ores, granite and china clay down from the Luxulyan valley - first to Par docks (in my Southwest corner) and later to far away Newquay built on the North coast. Jetties for loading large ships were also constructed in the Fowey estuary, on the East of my layout, still in use today, and the branch line was extended from Par docks to Fowey on the Southeast although that track and station were removed in the 1960s. The short "loop" between Par & St Blazey still provides an important connection between the main line and Newquay |
| 2018 | Oct |  | Respecting advice to "walk before you run", began constructing simple experimental/practice figure-of-eight layout with an underpass beneath a station with two platforms and a working 4-gate level crossing. All control and monitoring from "glass panel" on laptop programmed in Python. Added 2mm cube magnets under locos to operate trackside reed switches and Hall effect detectors. Experimented to stabilise train speed on up/down (2.5%) gradients and to decelerate and stop at the right place in the station. |
| Aug |  |
* Joined Model Electronic Railway Group (MERG).
* First investment in MR. Farish (Poole) Class 25 from eBay. * Borrowed length of flextrack and H&M Duette controller - "layout #1"! * Began experimenting with directly (not "DCC") controlling traction to achieve reliable slow movement and realistic acceleration and deceleration. |
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| Jul | Looked at MR as a hobby, particularly N gauge - which I chose to go ahead with. | ||
| 2017 | Apr | "Retired" from main day job (electronics R & D). | |
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