Difficult to say from the outside. And looking at the inside may answer the question, but renders the answer useless.
Maybe a simple test setup which is able to drive them closely to the borders of the SOA, if the don't fail quite soon, they're probably not fake. Don't forget to mount them on a heatsink for stress tests.
Greetings,
Andreas
Maybe a simple test setup which is able to drive them closely to the borders of the SOA, if the don't fail quite soon, they're probably not fake. Don't forget to mount them on a heatsink for stress tests.
Greetings,
Andreas
Hello Rod,
I measur around 9,5 Mohm
I measur around 9,5 Mohm
It's suspect.
You have the ON (onsemi) branding, but ON don't have a DN2540 or anything-2540.
Quick test: a depletion FET should have continuity from D to S when metered with DMM on 200 ohm range, even with G floating. One of my 2540s measures 8 ohm like this.
Many European hobbyists solely use their bank account for payments while American suppliers just accept credit cards. As it seems the situation for Europeans is changing because it's possible to make a payment to Mouser via a bank in Germany, I found out a couple of months ago. Until then I had the same problem with US parts which are hardly stocked by local wholesalers (which don't sell to private persons). There's your problem
Hello Rod,
I measur around 9,5 Mohm
Sad to say, that sounds like a relabelled bipolar transistor, or enhancement-FET.
You can try it in a CCS connexion - but my guess is that it will give a current of zero, if it is the fake we suspect it to be.
Yes, in Europe, Mouser is the only practical access to any kind of franchised supply of any depletion-FET, but this works only for GBP 50 orders (in the UK) - or you pay high shipping costs.
There is a reliable reseller of these in England;
2 x Supertex DN2540N5 DN2540 Depletion Mosfet DIY CCS | eBay
Excellent guy and a member of this forum.
Shoog
2 x Supertex DN2540N5 DN2540 Depletion Mosfet DIY CCS | eBay
Excellent guy and a member of this forum.
Shoog
It shouldn't be a problem to buy 100 and get them sold on this forum here. As far as I see, there are no restrictions any more and these can be sold in the EU now: DN2540N5-G Supertex | Mouser
Or you use other depmosfets like these from infineon: N-channel MOSFETs: Depletion MOSFETs (60 - 600V) - Infineon Technologies
Or you simply use enhancement fets. In the cascade oder "Ring-of-two" config: http://bildarkiv.hififorum.nu/Ryssen/Pic/Rör/diyAudio-CCS-beta2.pdf
Or you use other depmosfets like these from infineon: N-channel MOSFETs: Depletion MOSFETs (60 - 600V) - Infineon Technologies
Or you simply use enhancement fets. In the cascade oder "Ring-of-two" config: http://bildarkiv.hififorum.nu/Ryssen/Pic/Rör/diyAudio-CCS-beta2.pdf
Farnell sells the bsp129 at 69p:Yes, in Europe, Mouser is the only practical access to any kind of franchised supply of any depletion-FET, but this works only for GBP 50 orders (in the UK) - or you pay high shipping costs.
http://uk.farnell.com/jsp/search/pr...|pcrid|13359057789|kword|bsp129|match|p|plid|
SMD but great one for CCS and gyrators, have used it with great results
Ale
In the cascade oder "Ring-of-two" config: http://bildarkiv.hififorum.nu/Ryssen/Pic/Rör/diyAudio-CCS-beta2.pdf
This is the correct URL:
http://bildarkiv.hififorum.nu/Ryssen/Pic/Rör/diyAudio-CCS-beta2.pdf
rgds,
tri-comp
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