Hi Everyone,
During quarantine I have some more time for my projects. I orderered a couple of PCB's for Samuel Groners Laboratory grade measurement preamplifier and I also wanted to order all the parts through mouser or digikey.
Most of the parts were easy however there where a couple that are now end of life and I'm having trouble finding replacements.
Here are the transistors that I was having trouble with finding a replacement or would like confirmation for.
Type - The replacement I have found.
MMBF5462
BC850CMTF
I have also posted this in as a reply on the thread about the preamplier. However nobody seems to reply there 🙁
Unfortunately the manufacturer doesn't provide a replacement either.
Thanks in advance!
Hidde
During quarantine I have some more time for my projects. I orderered a couple of PCB's for Samuel Groners Laboratory grade measurement preamplifier and I also wanted to order all the parts through mouser or digikey.
Most of the parts were easy however there where a couple that are now end of life and I'm having trouble finding replacements.
Here are the transistors that I was having trouble with finding a replacement or would like confirmation for.
Type - The replacement I have found.
MMBF5462
BC850CMTF
I have also posted this in as a reply on the thread about the preamplier. However nobody seems to reply there 🙁
Unfortunately the manufacturer doesn't provide a replacement either.
Thanks in advance!
Hidde
RS part number 807-5059 for BC850CMTF.
Farnell supply a variety of equivalents; https://uk.farnell.com/webapp/wcs/s...logId=15001&langId=44&categoryId=700000004636
Hope that helps but mostly obsolete components are difficult to source.
Farnell supply a variety of equivalents; https://uk.farnell.com/webapp/wcs/s...logId=15001&langId=44&categoryId=700000004636
Hope that helps but mostly obsolete components are difficult to source.
Awesome! Good to hear that I can still buy them (for now) at farnell. Now I just need to find a replacement for the other transistor!
I used these BC850C from Mouser: 771-BC850CW135
I'm still having some problem with my builds so if I picked something wrong for this component I would be very interested😉
I got the MMBF5462 from Digikey about a year ago, but I can see that they are now out of stock
I'm still having some problem with my builds so if I picked something wrong for this component I would be very interested😉
I got the MMBF5462 from Digikey about a year ago, but I can see that they are now out of stock
P channel jfets are almost extinct
The ones that you can still buy are all lower than the 40V rating of the MMBF5462
The ones that you can still buy are all lower than the 40V rating of the MMBF5462
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I'm not sure whether the 40V rating is required. The preamplifier can be ran off batteries (2x 9V, Drain and source are connected to +- Supply voltage -> 18V ds).
It's just that I don't understand the schematic completely here and thus I don't know the Idss and Vgs requirements. My discrete transistor knowledge is quite basic, which also doesn't really help.
I could share the schematic, but I think that is a bit unethical since it's been published in Linear Audio Volume 3 and Samuel Groner has put a lot of effort in it. It's already a steal of an article for the 3.50 euros.
I've contacted Rochester (an ON Semi partner that still has about 200 in stock). However I haven't had a response yet.
Rochester Electronics has the MMBF5462 in stock -- tricky ordering from them outside the US for some reason.
I don't think that the device is "mission critical" in the current source and voltage reference for Sam's LNA -- perhaps MMBFJ175.
I don't think that the device is "mission critical" in the current source and voltage reference for Sam's LNA -- perhaps MMBFJ175.
One more thing -- read the LA article again for the purpose of the MMBF5462 and BC850 -- you should be able to find substitutes which are certainly adequate.