29 Oct
2025
29 Oct
'25
11:38 a.m.
Hi Christian,
what do You think about:
2N3640 -> 2N3906
2N3693 -> 2N3904, 2N2222A, BC337-25
Best
Andreas
Please contact me offlist.
Am 27.10.2025 um 16:38 schrieb Jon Elson via cctalk
<cctalk(a)classiccmp.org>rg>:
On 10/27/25 05:26, Christian Corti via cctalk wrote:
It seems that nowadays you can't get *any*
replacement for failing DEC 3639 aka 2N3639 transistors. All parts are obsolete and
unobtanium, e.g. 2N3640, PN3640, MMBT3640 and so on.
So, what can be used instead? The most important electrical parameter is the storage
time. It needs to be *very* low, around 20-30 ns.
Oh, it apparently is Silicon. So, an MPSH81 should really do well.
Jon