[Lowfer] Epson Question

[Johan Bodin]

Hi

the fundamental frequency component of a square wave
has an amplitude of:

Vsine_rms =3D Vsq_wave_peak_to_peak * square_root (2) / pi

which means=20

Vsine_rms =3D Vsq_wave_peak_to_peak * 0.4502

or

Vsine_peak_to_peak =3D Vsq_wave_peak_peak * 1.2732

(Assuming 50/50 % square wave duty cycle)

Although it may appear surprising, the Vpp of the fundamental
frequency component is larger than the Vpp of the square wave itself :-)

To run class D, you can put a series resonant circuit of sufficient
loaded Q, say 5 or more, between the square wave generator and
the load (XC =3D XL =3D 5*Rload, or more).

The series circuit will pass only the fundamental frequency so the
generator will see only negligible loading on the harmonics.
This is much better than using a "grounded C input" lowpass
filter directly at the generator output (which will cause high current
switching spikes =3D more switching loss).

BTW, I would guess that the Epson oscillator has a quite "weak" output
stage so it will probably deliver more power into a load >50 ohms.

73
Johan SM6LKM