1. Very ancient model                                                              2. More recent: Kimber-Allen valves                                 3. Very recent Peterson Valves
(Extracted from an authentic Merklin Pipe Organ)



During a long time, Magnet valves had the form represented in picture 1
Wire were made with cotton, very dangerous towards fire risks
Support was on the opposite side of the pallet, giving a much more voluminous part.

The recent models, (picture 3) are much more compact.