A Tremulant just produces a periodic variation of the amplitude or volume. There's no frequency modulation like a vibrato. That's why it doesn't sound so intensive like the vibrato, which was introduced with the BV / CV models. The contruction of the tremulant was a set of switches, which shorted some resistors. These switches were driven by a cam shaft, which was coupled to the run motor. Intensity was controlled by a variable shunt resistor and affected both manual. The model E had tremolo intensity controls for each manual.
Steffan Diedrichsen
The content of this page is Copyright (C) 2000, 2001, 2002 Geoffrey T. Dairiki and
the other authors of the content, whoever they may be.
This is free information and you are welcome redistribute it
under certain conditions; see
http://www.dairiki.org/HammondWiki/opl.html for details.
Absolutely no warrantee is made as to the correctness of
the information on this page.