It looks like Diodes, Inc. is prioritizing their fabs for other items besides discrete BJTs.
any universal type of TO92, PNP, will do the job, taking care of pinout
on my side of Pond, BC556, BC560, BC640
on my side of Pond, BC556, BC560, BC640
Thanks Guys. I don't know enough about electronics engineering yet to choose a reliable substitute by myself for Papa Nelson F2J design but I do understand the importance of noting the pinout when working with alternate devices. How about this guy, its cheap and plentiful:
https://www.mouser.ca/ProductDetail/onsemi-Fairchild/BC32740BU
I also found that ZTX550 is not scheduled to be restocked and this part is now a blackhole on OCTOPART but ZTX551 is scheduled to be re-stocked at Mouser FWIW:
Thanks!
https://www.mouser.ca/ProductDetail/onsemi-Fairchild/BC32740BU
I also found that ZTX550 is not scheduled to be restocked and this part is now a blackhole on OCTOPART but ZTX551 is scheduled to be re-stocked at Mouser FWIW:
| Mfr. Part # ZTX551STZ Mouser Part # 522-ZTX551STZ | Diodes Incorporated | Bipolar Transistors - BJT PNP Medium Power | Datasheet | 1,993 Expected 2023-05-08 |
|
| Mfr. Part # ZTX551 Mouser Part # 522-ZTX551 | Diodes Incorporated | Bipolar Transistors - BJT PNP Medium Power | Datasheet | 3,900 Expected 2023-05-08 |
|
Thanks!
Oh my next question is: When choosing SMPS, what current rating do I need per channel for F2J? 3A or higher per channel? De-rating curve seems to start at 50 degrees C for most common SMPS which I expect will be the operational temperature inside the chassis, maybe slightly higher? I plan to use 2U chassis with CPU coolers on the active output devices. If I use 2x 24V volt sources: Mouser # 209-LCS75US24 that I already have is 3.2A each but around 2.5A at 55 Deg C going to be good enough? Should I choose something bigger? The engineering department at my work (I work in RF testing) suggested Vicor AC-DC or DC-DC modules which in our industry provide a very low level hash or low noise SFDR.
The rule of thumb around here with SMPS with Class A seems to be to have the PSU rated at double the required current. The F2J draws about 2.5A per channel at 24V, so 120W should be OK per channel. I use a 240W Meanwell in my F2J, and it seems to work OK.
The resistors on the boards will be burning off a significant amount of heat themselves, so make sure you have very good case ventilation. I hope your CPU coolers are big and up to the task. I know you aren't using a Modushop case but for reference, I wouldn't attempt an F2J in a 2U sized chassis (heatsink size).
Other than that, you should have a relatively straightforward build.
Other than that, you should have a relatively straightforward build.
It seems ZTX550 is still unavailable for sources in the US. Wondering if KSA1013 would be a suitable substitute?
for J2, one can almost use Cucumber in place of ZTX550
use any damn Uni PNP transistor
KSA1013 is sort of unnecessary potent beastie - you gain power, loose Beta ...... and Beta is useful there
it'll work, slightly better than Cucumber
use any damn Uni PNP transistor
KSA1013 is sort of unnecessary potent beastie - you gain power, loose Beta ...... and Beta is useful there
it'll work, slightly better than Cucumber