Add-A-Stop Combination Action

Add-A-Stop Combination Action
This is the prototype "Add-A-Stop" miniature combination action (about 6" by 3.5"). It controls one stop by means of 16 pistons, a reversible, a CANCEL button, and an optional SETTER button. “Hold-and-set” operations are also supported. The stop action’s magnets can be fired with positive or negative levels. The installer can regulate the duration of the magnet firing pulse and can also control an optional delay from piston press to magnet firing so that the stop will move in unison with the existing stops.


The inputs at the bottom edge of the board can be via several types of terminal blocks or by direct soldering to the circuit board. From left to right, this prototype board has large screw terminal blocks, pads for direct solder connection, small terminal blocks, and then two types of "spring clamp" terminals that grasp the wire with jaws that can be opened by use of a small screwdriver pressed against the orange lever or into the slot above the wire entry point. Other terminals can be used as long as they match the .200" hole spacing.

The left-most 19 positions are for pistons 1 through 16, a separate reversible piston, SET, and CANCEL. They can be wired in parallel with an existing combination action.

The right-most 5 positions are for the stop’s contact, the ON magnet, the OFF magnet, ground, and the positive power supply. Two solid-state fuses are provided, one for each magnet, and the board contains filter circuits so that its inputs will not be triggered accidentally by random electrical noise that might be present in the organ's existing control wiring. If more than 16 pistons need to be used, then two or more Add-A-Stop boards can be installed, wiring in parallel for the SET, CANCEL, stop contact, ON, and OFF connections.

Three LEDs show the status of the board and of the various inputs, helping the installer prove that the wiring is correct and that the unit is working properly. (No, the stop tab does not come with the board!)

If you would like to read through a draft of the Add-A-Stop documentation, please feel free to do so at this location.

(This page was created on 5 Oct 2001 and updated on 11 Mar 2002.)