Hi Daviddoria,
Thats quite a high frequency for a beginner.
Too many things start to affect high frequencies like that.
I would suggest 8 turns for the collector coil,
and 5 or six for the base coil, both at about 5/16" and
if the wire is not insulated, make sure the turns are not
touching each other, but both coils next to each other.
I am sorry i did not make the transistor and bulb example
very clear.
If you want to understand circuits, i will have to explain
the action of a transistor better.
That circuit is just an illustration to show that a small
current through the E-B junction allows a greater current
through the E-C junction.
This means that variations in a small current can be copied
in a larger current going through the collector, this is
called 'Gain'
A transistor with a gain of 20 would give a current change
20 times greater through the collector, from the current
through the base.
The little box in that drawing of the bulb and transistor
shows two little arrows.
Those arrows show the current paths, one through the base
and one through the collector.
If this is still not clear, i will try to explain it in
a different way.
Best of luck, John
note:
the second smaller coil is to pick up the current changes
in the collector coil, and feed them back to the base,
which controls the current through the collector. The
current quickly reaches a point where it wont increase
any more. The change then stops. It is the change that is
fed back, and when the change stops the collector current
starts to fall, because it was partly helped up there by
the coil on the base. When the collector current starts
to reduce, that change is picked up as a change by the
coil in the base, and some signal is given to reduce the
collector current. So the collector current reduces more,
that change of current is seen by the coil in the base
and more signal is sent to further reduce the collector
current. The collector current quickly reaches a point
where it wont reduce any more. So it stops reducing.
Then there is no change in the collector current, and the
coil on the base no longer picks up any change. The
signal from the coil on the base stops, the collector
current starts to rise. This change is picked up by the
small coil on the base, which instructs the collector
current to increase. This action means that the circuit
swings backwards and forwards from low current to high
current, it is an oscillator.
This current doesn't go backwards, its just a changing
forward current through the transistor. It is often
treated as AC and in a lot of ways its OK to do so.