I've been clear on this - the schematics of the J2 will be
released when production ceases. I'm tired of the
commercial clones using my trademarks, claiming to be
accurate reproductions.
In the meantime, you should have enough smarts to cobble
together your own versions based on the simplified
schematics. Much more fun that way.
Quite understandable, no-one should put up with that.
And we will supersede you anyway
Magura
I tried that, but they are not sharing well. I have a test setup where this was supposed to bring some fun.
No fun so far, just blown devices.
Magura
How close did you match your device?
How close were the parallel devices thermally coupled with one another? (the thermal resistance between mounted devices)
Maybe the device's Id just increase too much for the same Vgs with increasing temperature (which is likely, as it is a very high gm device), thus easily go into thermal runaway.
I have no idea how bad is the thermal run-away tendency, as the datasheet does not include Id vs Vgs graph for different temperature, and I do not have a single device on hand to test it myself.
BTW, count me in if there is a GB.
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They were matched within 10mV, mounted on a copper bar.....trust me, we have the same idea, I just had it a while ago
Thermal runaway just seems hard to control with those critters.
Magura
Magura, Good luck,
If there is a GB count me in.
There is for sure
Crying may not do, but the threats....oh boy
Magura
Do we need matched pair in Mu follower design?
naah .......
even if matching can't hurt
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They were matched within 10mV, mounted on a copper bar.....trust me, we have the same idea, I just had it a while ago
Thermal runaway just seems hard to control with those critters.
Magura
Thanks for the information, it certainly saved me from burning some LUs.
If Thermal runaway was so bad, then we will need a design that help to ensure equal sharing of current.
It is such a pity that it cannot be paralleled out of the box.
This morning i have called an italian distributor for Semisouth devices.
Hi tell me that now they are going to sell Power jFet with 100 mOhm SJEP120R100 type, that is a little big (17A vs.15A) (i think this is also ok).
They send me a quotation for 10 pieces.
Prices is 35 Euros each plus shipping charge from Usa (about 50-60 Eu).
Francesco.
Hi tell me that now they are going to sell Power jFet with 100 mOhm SJEP120R100 type, that is a little big (17A vs.15A) (i think this is also ok).
They send me a quotation for 10 pieces.
Prices is 35 Euros each plus shipping charge from Usa (about 50-60 Eu).
Francesco.
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Hi.
I also called the italian distributor.
For 100 pcs the price is lower.
Note that the price is w/o VAT (so consider +20%).
The all-in price is - again - in the surroundings of EUR 35, matching included (if a GB will be organized, due to the - relatively - low quantities, the matching is not only advisable but -AFAIK- mandatory!).
Stay tuned!
GuidoR
I also called the italian distributor.
For 100 pcs the price is lower.
Note that the price is w/o VAT (so consider +20%).
The all-in price is - again - in the surroundings of EUR 35, matching included (if a GB will be organized, due to the - relatively - low quantities, the matching is not only advisable but -AFAIK- mandatory!).
Stay tuned!
GuidoR
Now are we sure Nelson is using the SJEP120r in the J2 ? If you refer back
to the verry first of the article he talks about the larger 30A device with a
power rating of ~270W and a cost of $60. Yes he shows a graph using
the SJEP120r in the F2 so which did he use? Rember the 120r is only rated
at 136w.
to the verry first of the article he talks about the larger 30A device with a
power rating of ~270W and a cost of $60. Yes he shows a graph using
the SJEP120r in the F2 so which did he use? Rember the 120r is only rated
at 136w.
They were matched within 10mV, mounted on a copper bar.....trust me, we have the same idea, I just had it a while ago
Thermal runaway just seems hard to control with those critters.
Magura
What do you think if we put a source resistor to each device in a group?
Have you tired it?
30 A and 1200 V are referred in general about maximum capability for these series devices, i think. But i think Nelson use the "little" devices with 125 mOhm SJEP120R125, because in his circuit (source grounded amp) is suitable a little input cap device. On other hand, you can read at 6moons that J2 employ just this component (at the end of this page view the pdf attachment).
Francesco.
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