The maximum voltage V induced in a coil of wire whose wire turns intersect a changing magnetic field is given by:

V = A x N x dB/dT

V = generator output voltage (volts)
A = cross sectional area of the coil of radius r (A =πr² in meters²)
N = number of turns of wire in the coil
dB/dT = the rate of change of the magnetic field (Tesla / sec)

Voltage (V) generated by my construction is proportional to the strength of the magnets (M – tesla) and the rate at which they are spun (dM/dt tesla per sec), the area (A – m2) of the coil(s) and the number of turns of wire (N), so V = N x A x dM/dt so if you have N = 1000 turns, magnet surface strength (for 1 magnet) = 1 tesla, rate of turning = 5 turns a sec (so dM/dT = 5 tesla / sec), area A = 0.001m2 then V = 1000 x 0.001 x 5 = 5 V (peak).

The voltage induced in the coils will are an AC signal.

The Magnets used in this construction are rated by the manufacturer at 13,200 Gauss or 1.32 Tesla.  The magnetic strength of the earth (stronger at the poles, weaker at the equator) is measured in nano Teslas.

This conversion utility was useful.