Jelly bean logic level fast switching transistor BJT/FET - Page 1
Forum section: electronics / projects

author: c64
author_rank: Frequent Contributor
timestamp: October 03, 2020, 04:58:14 am
content: What is your favorite?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 03, 2020, 06:02:00 am
content: 2N3904/6I grew up/live in the US, so I go by American designations. Doesn't really matter, could be 2SA/C something or other (uhh, I forget what the closest JP commodity cross is), or BC547 (British), or...General purpose BJT, 200mA, 60V (breaks down at ~100V), reasonably fast (~4pF, 300MHz), good for amplifier and logic stuff. SMTs, replace 2N with MMBT. For bigger stuff, switching etc.: 2N4401/3 (600mA), PBSSxxx (amperes), etc. Also, since BC847 is available in duals, I've taken to using them often.Or for direct logic level switching, where you really can't be arsed to add bias resistors: DDC114YU (NPN), MUN5114DW1T1G (PNP), etc. (If you can be only half-arsed to add resistors, consider using SMT resistor packs: four for the price of one.)Honorable mention, the PN2369 (and metal-can 2N-, and SMT MMBT-), the OG "switching transistor". Gold doped, like 7400 TTL; very short storage time, at the expense of Vceo (only 15V -- though its quite a bit more than TTL runs at), and hFE at low currents (so, not a great general-purpose amplifier).2N7002: general purpose NMOS, pretty slow (30pF), logic level, useful to fair load currents. BSS84 is the nearest "complement". (MOS can't really be complementary in the way BJTs can; the similarities are more in broad strokes.)BSS138 is a common pick for lower logic levels (2.5, 3.3V).RUM001L02T2CL: smaller, sleeker, ESD-sensitive-ier. Comparable performance to a... 74HC open-drain bus driver, I suppose, but higher voltage, and just the transistor, no input buffering, no clamp diodes (besides the teeny tiny zener shown on the diagram). Rated down to 1.2V "on".Higher currents or voltages, basically anything; too many to list, too easy to shop for.Tim

author: magic
author_rank: Super Contributor
timestamp: October 03, 2020, 08:26:07 am
content: On paper the BC5xx are supposed to be slightly slower than 2N390x, at least in terms of typical fT at 10mA (300 vs 500 or so).And not rated for 200mA collector current, although most 2N390x datasheets show terrible high current hFE anyway.

author: Benta
author_rank: Super Contributor
timestamp: October 03, 2020, 03:03:40 pm
content: Quote from: magic on October 03, 2020, 08:26:07 amDon't confuse fT with switching speed, they're two different animals.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 04, 2020, 02:35:36 pm
content: I learned electronics with BC547 / BC557.Then BC 327 / BC337 for higher currents.Also BC516 / BC517 (I think that were their numbers) for small darlingtons.These days I just bought some 600 transistor box for TO-92 which is easy to breadboard, and a "book" with some thousand or so SOT-23 for small PCB projects, then downloaded all the datasheets, and made a simple overview of them in HTML with links to the local datasheets.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 04, 2020, 05:08:18 pm
content: In the USSR, the most popular were KT315/KT361.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 04, 2020, 05:11:39 pm
content: Even earlier, MП41/MП35 were very popular. And I really liked the germanium ГТ402/ГТ404

author: Benta
author_rank: Super Contributor
timestamp: October 04, 2020, 05:25:01 pm
content: Why would the OP (Australian) want historic Russian transistors?

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 04, 2020, 06:05:27 pm
content: Quote from: Benta on October 04, 2020, 05:25:01 pmTo know what life was like behind the iron curtain. And how we went into space.

author: David Hess
author_rank: Super Contributor
timestamp: October 06, 2020, 03:15:40 pm
content: Fast switching transistors were never very common or commonly used so the selection is small. The NPN 2369 in various packages is still available and likely the most popular. I do not think any PNP fast saturated switches (5771, 3640) are produced anymore. Unfortunately RF transistors are not replacements for them.Vceo 15 voltsStorage time 5 nanosecondsTurn-on time 8 nanosecondsTurn-off time 10 nanosecondsIf you are referring to general purpose transistors, then I have to go with 2N4401 and 2N4403 over the 2N3904 and 2N3906.