SemiSouth power Jfets .......... FW J2

[sp300b]

Picture above comes from here

[Zen Mod]

is heatsink colder in steady state or playing muzak ?

[Zen Mod]

naive question - did you re-checked bias ?

[sp300b]

Bias is OK. Zen, You could check when You have time. Put IRFP150N on test under 2A on heatsink and measure temperature after let say 5 min (you have laser tool for temp. measurement, if i remember correctly). Do the same one day after (let the heatsink become cold) on with SJEP120R100...and we'll see.

[Zen Mod]

nope I don't have any doubts - as I see it - both rheostats are the same , under quiescent conditionsbe it IRFP rheostat or SS rheostatso - just chill , take a shot of rakija and enjoy in sunday with family - with or without music

[Magura]

This just keeps getting better....First breasts, now rakija......what's next?Counting out boobs and booze, the fluffy serb is right. The reason for JFET's having higher efficiency in inverters, is that they cross zero in that application.Magura

[Zen Mod]

Magura - refresh my memory - what's that black material you're using as heat spreaders carbon , cut from brake plates ?

[Zen Mod]

btw - Magura - seems that Sloba somehow manage to get in Zen Mod state ........ brain confused :sarcastic_hand:now he can see how it's being me - all the time .......

[Fukushima]

Let's check the opinions of the others on Big Diy (link)

Hehe, to nema veze sa primenom tih fetova u pojacalu, ako imas recimo 50W disipacije na tranzistoru onda imas 50W pa makar bio i od grafena

[sp300b]

Hehe, to nema veze sa primenom tih fetova u pojacalu, ako imas recimo 50W disipacije na tranzistoru onda imas 50W pa makar bio i od grafena

Ok, ok...može bit da sam lupio, pa sam ostao živ.Ipak, manje mi se greje nego Babel originalni, a mrzi me da proveravam bias. Ubedjen sam da je sada na 2A u mirnoj tački i da ne mrda.Da li sam tamo na Babaelu bio nagruvao struju preko 2A, teško mi je sad da se setim...Pomislio sam na momenat da je u pitanju RdOn, koji je po svemu sudeći manji kod SIC MOSFETA, pa stoga manje energije inerno troši na grejanje...

[Sipi]

Tako je Slobo, povela te prica o prekidackom rezimu rada, nema veze... Ja bih pored mirne struje proverio da li ima i kolika je razlika u temperaturi izmedju tela tranzistora i hladnjaka.

[sp300b]

Temperatura hladnjaka je 42 stepeni. Radio je bar sat vremena pre merenja.edit: Temperatura sobe je 22 stepeni

[Sipi]

Temperatura hladnjaka je 42 stepeni....

A jel' mozes da izmeris temperaturu na samom telu tranzistora?

[sp300b]

A jel' mozes da izmeris temperaturu na samom telu tranzistora?

Izmerio 70 stepeni

[Sipi]

E to je to: hladnjak je 'ladan a tranzistor kuva - slaba termicka sprega izmedju tranzistora i hladnjaka. Dakle, na kucistu (telu tranzistora) ne bi trebalo da bude vise od 5 (uvr' glave 10) stepeni vise nego na hladnjaku, inace ce ova situacija polako da odvede u proboj tranzistora zbog preteranog zamora materijala vecom temperaturom od optimalne.Dakle, mesto na hladnjaku gde montiramo tranzistor treba da bude glatko i odmasceno, liskun treba da bude sto tanji a namaz kvalitetne paste izobilan. Pozeljna je podloska koja omogucuje da tranzistor bude cvrsto stegnut a pritisak ravnomerno rasporedjen po telu tranzistora i onda nece biti problema.

[Magura]

Magura - refresh my memory - what's that black material you're using as heat spreaders carbon , cut from brake plates ?

Yes, that is a type of carbon, that is 100% carbon, as opposed to the regular types which is 90% carbon at best.It's called pyro-carbon, and is used for carbon brakes, surgical implants, and heatsinks for aerospace electronics and the like.Mine started out the life cycle as test brake discs for the car cabon brake project.Magura

[Magura]

btw - Magura - seems that Sloba somehow manage to get in Zen Mod state ........ brain confused :sarcastic_hand:now he can see how it's being me - all the time .......

Yeah, soon he will start growing long hair and begin brewing rakija......Magura

[Zen Mod]

E to je to:.......

:rules:elem - valjda ce uskoro stici MOX-ovi ( sigurno pre punta ) , pa ce vadi djunte napolje i sredi to kako Bog zapoveda

[Zen Mod]

Yes, that is a type of carbon, that is 100% carbon, as opposed to the regular types which is 90% carbon at best.It's called pyro-carbon, and is used for carbon brakes, surgical implants, and heatsinks for aerospace electronics and the like.Mine started out the life cycle as test brake discs for the car cabon brake project.Magura

you told me once how much they're more effective than Cu spreaders ?

[sp300b]

E to je to: hladnjak je 'ladan a tranzistor kuva - slaba termicka sprega izmedju tranzistora i hladnjaka. Dakle, na kucistu (telu tranzistora) ne bi trebalo da bude vise od 5 (uvr' glave 10) stepeni vise nego na hladnjaku, inace ce ova situacija polako da odvede u proboj tranzistora zbog preteranog zamora materijala vecom temperaturom od optimalne.Dakle, mesto na hladnjaku gde montiramo tranzistor treba da bude glatko i odmasceno, liskun treba da bude sto tanji a namaz kvalitetne paste izobilan. Pozeljna je podloska koja omogucuje da tranzistor bude cvrsto stegnut a pritisak ravnomerno rasporedjen po telu tranzistora i onda nece biti problema.

Sipi, zahvaljujem. Napravio sam tanji liskun pomocu skalpela (ovi providni su svarno bili debeli). Unistio 4 dinara za pričvršćenje Mosfeta na ZM nacin i ponovi prišrafio. Nadam se da će biti bolje sada. Sada idem da rakijam

[sp300b]

:rules:elem - valjda ce uskoro stici MOX-ovi ( sigurno pre punta ) , pa ce vadi djunte napolje i sredi to kako Bog zapoveda

[sp300b]

ZM, napon na izlaznom otporu je 0,92V na oba kanala. Dakle bias 1,85 A, ako su otpori stvarno 1 Ohm...Neka, doci se MOX, pa ce ga narihtamo ponovo na 2A.