My O Gauge Journal on
Modelling the GWR
A personal Journey
Developing a bell communications system
Most electric bells are continuous ringers. For my purpose they needed to be converted to single gong type rings so a bell code could be sent to any one of them by pressing a button. A number of cheap 3.5v bells, (£2.75), were obtained from ISG Ltd and converted to single ring. The circuit diagram below shows how they were connected together, (click it for a larger view)..
The bells are fixed to the side of each control box as shown here and are available from www.edulab.com
It is necessary to convert the bell strike to a single one on pressing a button. So the following circuit change is necessary.
This alteration merely does away with the make and break arrangement it comes setup with.
Unfortunately, changes in temperature have meant that some of the bells will not produce a single chime. As the bells were so cheap I am investigating replacing them with more robust bells. Using AC bells with DC current means a single ring can easily be achieved without any adjustment. I have chosen to use Friedland Underdome bells supplied by Securicare through Amazon. priced at £4.96 each. Here is one opened. Compared to the originals above its much more robust.
 |
 |
But although they are great for ringing, they still have issues for a single ring so I have decided to keep the original ones and retune them using washers at the dome base to cure the 'dong'! One problem was that the striking arm was not quite aligned with the solenoids once this was realised it cured the lack of a ring.