Self Destroying Mosfet with PIC

[Josuetas]

Hi, thanks to all for your concern.

First of all my drawing is wrong, the coil is a small 101k choke(100uH) i found it, tried it and it worked.

<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=2119&stc=1&d=119401832 1" />
The condensor it's also wrong (why didn't i check this?) i am using 1000uF 50V, and a 40v zener diode to clamp output voltage at condensor is not in the drawing.


This application is not a high voltage one, i am just getting like 80mA 40V output.

The Diode do is a fast switching diode, its even one of those big 6A ones.

I will double what Alain stated about MOSFET protection from the coil. Use a diode anti-parallel to the D-S of the MOSFET. If you have a scope, check the spikes on th D pin, but anyway, put that fast diode there.

Ioannis

Question: The diode proposed is from Drain to 12V voltage source? (Snubber diode). Wouldn't this avoid the condensor from charging? i though the idea of the boost converter was to use the current when the switcg is off to charge the condensor, wouldn't this kind of diode ruin that?.
Or
If the diode is from Drain to Source, could you draw it for me? i've never seen this before and.... i just don't get it... can you explain it?

I already added the resistor to gate.

Thanks for all your suggestions, they are all been taken in count.