Kapanadze Cousin - DALLY FREE ENERGY

[forest]

huh? If SPW47N60C3 is not good then it means we got much troubles with mosfets ?

[Farmhand]

Hi Magpwr / All,

i finally received my 47N60C3 MOSFETs (5), and put them into my Mazzilli osc., but they popped instantly using only a 12V battery (7Ahr) 
I tried this severall times untill most where gone, so they don't work in this circuit 1 to 1

Putting back my IRFP260N's it worked again as normal.

Looking at the main spec's of the both MOSFETs, not much difference is seen else then the higher Drain/Source voltage of the SPW47N60C3:

Vds 650V
Rds(on) 0.07 Ohm
Id 47A

compared to the IRFP260N:

Vds 200V
Rds(on) 0.04 Ohm
Id 50A

So it must be in some other parameter which make them unsuitable for this circuit as it seems they won't oscillate and put the gate wide open (need a higher then 470 Ohm gate resistor?)
On all damaged MOSFETs, the drain/source junction was shorted permanently.

Anyway, this shows that not all MOSFETs can be used in this circuit, be aware.

Regards Itsu

Hi Itsu, I'm sure you are probably already aware of this but DMM's can turn "on", "N" channel mosfet's when used in the diode test mode if the common from the DMM is put to the source and the positive DMM lead is put to the gate the mosfet can turn on and then appear to be broken. To turn it of put the positive to the source and the common to the gate, then be careful not to touch the gate with the positive DMM lead when measuring between the drain and source with the diode function.

..

[itsu]

Hi Itsu, I'm sure you are probably already aware of this but DMM's can turn "on", "N" channel mosfet's when used in the diode test mode if the common from the DMM is put to the source and the positive DMM lead is put to the gate the mosfet can turn on and then appear to be broken. To turn it of put the positive to the source and the common to the gate, then be careful not to touch the gate with the positive DMM lead when measuring between the drain and source with the diode function.

..

Thanks for the heads up Farmhand,

yes, i knew that, thats how i normally test my MOSFETs, but these are real gonners   
No matter what i do the D-S junction stays shorted.

Regards itsu

[Grumage]

Grum
I have an idea .......
for all the work you do in this community we buy you another ?

I put up 100.00 US towards repairs or a new scope.

No strings attached ,If you never post another thing here or elsewhere it does not matter to me .You are a very Good Man with the the best of intentions.

Thanks for all you do.

Chet

Dear Chet.

I have just come back to my desk after a couple of hours of "Open scope surgery" !! The patient survived the ordeal but no cure was achieved!!    The power supply board appears to go into high frequency oscillation around the input transformer.

You brought a tear to my eyes!! That is one of the kindest offers and compliment that I have received in a long while!! Thank you.

I will however persevere and contact the supplier to see if he has any spares.

Heart felt thanks, Grum.

[ramset]

Grum
Well another person has matched that offer of help for your ailing over worked equipment.
And that person did bring a tear to MY eye...........[he is a truly great experimenter/person who does Much for this community].

I will contact Peterae at O.U.R. for a possible way to disperse these funds to you should you need them .Unless Stephan can make a place for those who would like to help Here?

Grum It will be good for people to be able to help experimenters here, even a few dollars would be helpful and also make others feel they are playing some part in this work that benefits all.

a true privilege in my opinion.

thx
Chet