Which is probably because the specs are, ahem, optimistic. Get one that can output twice the power you need and it might actually work.

Bob

 

The thing is: I have bought more than 5 of them to drive 12 volt leds but I am tired...

 

They all have reduced prices maybe because they do not work properly and fail soon.

You are guessing wrong! Check the reviews before guessing. Most customers like them.

 

Does the seller post his own reviews?

 

The seller of a good hardly posts reviews unless he is a very legitimate one (if truly he tests it).

 

A little late to the fair but this is a favorite of mine: FDD6530A, N ch. LL, 36 m ohm, 21A, 20V, G +- 8V , ON @ 1V, Digi-Key.

 

Thank you so much.

 

If still wanting to make a boost with C555, might look at V regulator in post " Make 32V DC from
5V ..." # 10, Chat. The choke shown was also used for a 120V DC supply.

 

Thanks SO Much. All respect