SMPS for motorcycle intercom: some questions

[DaBit]

OK, so a flyback can be done also.

I'm wondering: how much cost or space does a flyback really save when compared to a single transistor (transformer with reset winding) forward converter or push-pull?

The flyback topology uses the least number of components, but is it really cheaper or smaller? I always used postfiltering on the secondary voltages using an LC filter to reduce supply noise.

The forward converter also needs a buck inductor which can be dimensioned for the required noise levels. It also seems that it needs less capacitance on the secondary side when the buck inductor is used in continuous mode.

With push-pull and current mode control the duty-cycle can probably be increased to 80% or more (at Vin,min), which means a lower RMS current through the capacitors, and thus smaller capacitors. I also doubt that I would need post-filtering. I could also use a smaller core, if I can get anything else than ETD29. Also, switch power dissipation is split over two switching devices, reducing the amount of copper area required for cooling. The extra cost would be twice the amount of windings on the transformers (but magnet wire diameter can be lower due to recued I2R losses) and a second MOSFET or transistor.

This is not based on any math or knowledge, just ideas.

Any comments?