Acouple of years ago I built a 7mm scale signal for a competition at my local club. The subject was the signal that once stood at Radstock on the Somerset and Dorset line. The signal was sited at the entrance to the Clandown Colliery branch. It was curious as it had arms facing in both directions and was devoid of spectacle glasses and lamps. A good photograph appears in The Last Years of the Somerset and Dorset by Colin Maggs, published 1997 by Book Law Publications.

Originally built on a display stand, I intended to install it on my Melcombe Magna branch, where it could be used to control the entrance and exit to the quarry branch. For some time I pondered how to operate the signal. The other signals on the layout are worked by mechanical linkage, but as the site for this signal would be rather inaccessible from under the baseboard, I decided the signal and its operating mechanism would have to be accessed from above.

When the time came to install the signals on the Yeovil Model Railway Group O gauge layout, one of our members, Mike Johnson of Jurassic Models, produced a signal mounting unit from thin ply. This is designed to plug into the baseboard and enables the signal to be operated by means of a servo motor. The unit will hold the signal firmly in position, whilst allowing the whole assembly to be withdrawn from its location with ease.

The unit consists of laser cut items with slots and tabs and takes only a few minutes to assemble. There are three separate items: the signal mounting with provision for fitting one or more servos, depending on the type of signal (photo1); the baseboard mounting socket, which is an open box with a flange, into which the signal mounting, complete with servos fits; and a template whose aperture gives the size for the hole in the baseboard and the outer dimension corresponds to that of the base the signal is built on (photos 2 and 3).

As I had already built the signal before receiving the Jurassic Models parts, a little extra cosmetic work was needed to cover the flange as my signal’s base was smaller (photo 4) I obtained the servos from www.giantshark. co.uk ref EMAO 121, along with a pack of 1 metre servo extension leads, to enable me to site the servo operating circuit board (obtained from GF Controls) in a convenient position near the front of the baseboard, making access easy for setting the travel of the servos. The circuit board requires an input of 7-12V DC. The extension leads are male/female. One end simply plugs into the end of the short lead on the servo with the other end plugged into the operating unit. When all is electrically connected, the travel of the servo arms can be set by simply turning a small knob on the operating circuit board, and the wires to work the signal arms can then be connected to the servos. After fitting the servos (these miniature servos seem to have a universal mounting, so there are many to choose from.) it was only necessary to mark and drill two holes for the signal operating wire to pass through, and to glue the signal to the mounting base. The operating wires to the arms were not connected until the wiring was completed in order to first set the travel of the servo arms. The signal was fitted from above the baseboard except for taking the leads from the servos to the circuit board (photo 5). Using extension leads means that when the signal is withdrawn, I can remove it from the layout by unplugging the extension leads as they are drawn up through the mounting socket.

I found the GF Controls servo operating unit very simple to wire and set up, mainly due to the clear instructions supplied with the unit. Bounce and dwell is also a feature of the unit, and this can be switched on or off. Each arm is operated via an on/off switch. I can recommend this as a very satisfactory way to mount and operate your signals.

Further details of the signal mounting can be obtained from Jurassic Models, Schoolhouse, Chedington, Bedminster, DT8 3JA, email: mike.jurassic@btinternet.com and GF Controls can be contacted by phone on 01695 632021 or by email via gfcontrols@hotmail.co.uk and their web site is www.gfcontrols.co.uk