What do they do?

I found this MOSFET circuit **broken link removed**, and I would really like someone to explain what the two capacitors do. And why are there two in parallel with two where different values. In another MOSFET circuit I'm doing I use 1nF grounded capacitors on each gate - but what are they exactly doing?

They are supply decouplers, the 470uF decouples at low frequencies, and the 0.1uF decouples at higher frequencies (where the electrolytic won't work well).

Are the diode really required?

I never bothered with them since they're built into the MOSFET and I know that they're slo but most MOSFETs can safely dissipate a small amount of avalanche energy.

Hero999 said:

Are the diode really required?

Click to expand...

Depends if you want a reliable project or not?, the external diodes cost very little but provide a great deal more protection than the internal 'diodes', which are probably only a byproduct of the manufacturing process anyway, and not intended for such use.