I have been making good progress with work on the underside of the layout, consisting of various changes to wiring and switching arrangements, which I had deferred until I could do this work without having to reach up under the layout (involving getting solder to flow uphill).
The changes are fairly mundane and are not easily illustrated, but one priority was to solder diodes across the coils of the electro-magnets for the uncouplers, to counter the backward ‘surge’ in the circuit that can occur when an electro-magnet is switched off. Paul Townsend has been trying to persuade me for several years to do this job, and the only reason for its not having been done sooner was that I was waiting until I could get the baseboards in front of me, while the layout is currently disassembled.
The first photo shows a SEEP electro-magnet with the diode soldered in place across the terminals. The cathode is wired to the Positive side of the circuit. I took the precaution of marking Positive terminals with red paint before doing this.
The second shot shows a diode soldered across the wires of one of Ray Hodson’s ‘Magic Magnets’ solenoids.
One of the other changes I made was to move an LED which I had already been using as an indicator when one of the uncoupling magnets is pre-selected, and to insert it in the electro-magnets switch panel immediately below the push-button that is operated to ‘fire’ a selected electro-magnet when a vehicle is standing or passing over it.
I haven’t previously illustrated the sub-baseboard wiring arrangements, and frankly I am not at all proud of them or of the untidy way in which the wires run every which way, but I have not had any difficulty in identifying wires when necessary.
This shot shows the connections to the section switches panel (which was shown in an earlier post, when the layout was being dismantled). Only minor changes have been made, mainly in order to install an isolating switch in the milk dock / horse landing. The wires that are bundled together here are being led towards the inter-baseboard choc-blocks, while other wires are connected to track feeds on this baseboard.
The next photo shows the choc block that feeds the electro-magnets switch panel. Changes here were mainly to accommodate a couple of additional LED panel indicators (not associated with the electro-magnets), which will be installed in the baseboard fascia when the layout is re-erected.
Although connections between the various switch panels and their respective choc blocks are colour-coded, most of the under-baseboard wiring is black. The red wires seen in this and other photos are the Positive returns in some of the circuits that are polarity critical, for example because in one or two cases LEDs are wired in parallel with those circuits. On the other hand, I didn’t colour code the Positive and Negative wires in the electro-magnets circuit, even though they too are polarity critical.
Those wires that cross the baseboard joint are led to choc-blocks connecting the wires across the joint. As explained before, these ‘plugged’ choc blocks are an improvised version.
Extra circuits will need to cross the baseboard joint in future, and I have installed a pair of proper plugged choc blocks for this purpose.
Baseboard B has now been set up in place of Baseboard A, so that I can start work on various minor wiring changes beneath that board.
These under-baseboard photos also enable me to show the point control arrangements – a simple system of rodding and cranks driven by the small brass drawer knobs seen a few weeks back.
(The large square of plywood also visible in the next shot is the underside of the turntable well. The turntable has yet to be built, and the operating mechanism will have to be added below the turntable well, unless I resort to Power by Forefinger.)
Changes of direction are effected by home-made aluminium cranks.
The point operating mechanism incorporates micro-switches to change the polarity of the crossing vees. The arrangement of the micro-switches, together with the associated drive mechanism, is a simplified version of a design devised by Iain Rice.
As soon as I have completed the minor changes to the wiring on Baseboard B, I should then be in a position to re-erect the layout.