Power
Supply
Required
in all versions. The transformer is 24 V.A.C. center-tapped at 1 amp.
This is a common part and is obtainable from Radio Shack, Mouser and
most other supply houses. The diode bridge is a 200V, 1 amp device.
Four 1N4001 diodes will work as well.
Input
Amplifier
Converts
the balanced signal from the console to an unbalanced signal with
a 100 ohm source impedance. This signal is used to drive the Leslie
amplifier, or the crossover circuit.
Crossover
Necessary
when using Leslie models 700, 705, 710 and 720. Directs audio below
150HZ to the stationary channel, thus the 15ä bass speaker and
higher frequencies to the rotor channel. This provides good bass response
and protects the Rotosonic drum speaker, or 10ä midrange rotor
speaker in the 720.
Tremolo
Switching
Required
in all applications. In the device we built, this was accomplished
differently, but for ease of construction, the small relay does a
good job. A D.P.D.T. may be used if more than one family is to be
used.
Turn-on
Switching
All
11 pin Leslies require a connection between pins 5 and 6 to activate
them. Obviously, this circuit is needed only when 11 pin cabinets
are used.
Notes
B+
for older consoles and later tremolo kits is not provided. Current
for these applications must come from the organ pre-amp, or in early
consoles, a discrete power supply.
Connections
for almost all cabinets are shown. Although the 700 and 705 will operate
successfully, do not expect the tonal quality of dual rotor models.
This circuit
WILL NOT WORK with brand specific models, i.e. 100, 101, 102, 103,
212 and others.
As with all
electronic construction projects, keep everything neat, leads as short
as possible and use extreme caution where line voltage is present.
On 9 pin sockets, pins 8 and 9 MUST be insulated with heat shrink
tubing.
I think you'll
be surprised at how good most dual rotor Leslies sound...even the
solid state models. The 720 is very convincing.
Enjoy.
