How a normal Bedini circuit works:

Usually the "simplest" Bedini circuit has two coils bifilar wound
on the same iron core. The transistor acts as a "inverting"
amplifier. A true AC amplifier is "bipolar", that is,  they go +/- while
this single transistor circuit here is a "monpolar" - just "+" vs off.
So that means that feedback from the sense coil cause the drive
coil to try to cancel it self off. - Except that the both coils are biased
by the incoming permanent magnetic pole of the rotor. So the
rotor "sees" this cancellation mag field as mirroring of it's incoming
pole which is attracting it. Once the magnetic field becomes an
outgoing pole the AC amplifier flips around and the now the pole
is being repelled by it. This switch-around occurs at just the
right time because of the sense coil so that the interaction
*adds* energy to the rotor. This circuit will work with a pendulum
too, which is how I saw it first used. So I call it a magnetic mirror.
These things are energy efficient as the coils keep trying to turn
each other off and add energy to the rotor only when necessary.

---

How the fan Bedini circuit works;

The fan circuit, you show, works in exactly the same way. Except the
coils are now *not* wound on a common iron core. They are ninety
degrees out from one another and are slightly off in terms of timing
but the circuit itself works the same way due to the residual magfield
in the rotor core. By using an NE555 one could probably find that adding
an RPM appropriate delay would bring the sense winding and the drive
winding back into better time alignment probably would help the power
of this fan based motor.

---

Why is it that it is not used more often? The circuit is not self starting,
therefore needs a helping hand or a small starter motor to turn initially.

:S:MarkSCoffman