Magnet valve for Ampico reproducing piano built by Walter Tenten, utilizing an
inexpensive ($2) 12-volt automobile relay designed for printed circuit board mounting.
 

The brass nozzle (with leather valve facing) is clamped to the printed cicuit card
so that it can be adjusted to align with the relay armature.
 

Chest magnet valve (OSI-Reisner HE, 90 ohms)
Width 5 cm, depth 2 cm, height of magnet above mounting
surface 5 cm, total height 7 cm.  The version for player piano
has a tube inserted into the magnet cap (the knurled aluminum
piece at the bottom) which extends down 13 mm (0.5 inch).
Weight 48 grams (1.71 ounce).
 
 

Reisner magnet-operated pouch valve for organ pipe chest.  A small spring inside
the pouch holds the felt pad to the hole below the pipe.  The pouch collapses into the
"clam shell" when the magnet valve opens and exhausts the pouch chamber to atmosphere.
This type of magnet valve operates faster than the direct action magnet valve (below).
Weight 118 grams (4.21 ounces).
 
 

Chest magnet valve for suction (OSI catalog)
 
 

Magnet valve from Kilgen organ
 
 

Magnet valve from Kilgen organ
 
 

Direct action magnet valve (OSI-Reisner 5528.12, 90 ohms)
Width 6 cm, height 4.5 cm, depth 1.6 cm
The pad diameter shown is 22.2 mm (0.875 inch).
Weight 51 grams (1.82 ounce).
 

Direct action magnet valve by Wicks, differing from the Reisner design
in the return spring arrangement.

Willy van der Reijden uses surplus 24-volt relays to pull the
valves of his MIDI-controlled Frati-Hymnia orchestrion.
 

Special magnet valve for the Welte-Mignon pneumatic action stack under the piano,
controlled by the "Musicalle" remote 8-roll carousel changer offered in 1928 by the
Welte-Mignon Corporation.  The carousel changer was probably built by the
National Automatic Music Co. of Grand Rapids, Michigan.  The special magnet
valve might be a Welte-Mignon product designed especially for this system.  The
steel armature disc has a facing of thin leather on one side and a piece of green
"billiard table" cloth on the other side.  A rim of thin copper or brass surrounds the
disc.  The U-shaped pole piece with coils is pressed into a brass plate which is
secured to a similar, permanently attached, brass plate so that the valve can be
easily opened for cleaning.  Several of these valves are need for a restoration,
see Dave Krall's article in 130601 MMDigest.