Old GE Transistor
 

I came by a bunch of 4JX1D765 transistors made by GE in around 1962. I can’t find a modern cross for them. Does anybody know if they are particularly useful - or just junk?

Most any transistor that old is collectible :yes: or useful as a replacement. It's very hard to find replacements for germaniums that once came in thousands of different types; now only a handful of off-the-shelf replacements remain (NTE, for example). Nothing gets the axe faster at the parts vendor than technology over 20 years old :sigh: Could you post a picture here maybe?

You could also list them on eBay with the word "FUZZ" in the title. Some joker will wire 'em up in a distortion pedal and abuse 'em like they were a 75-year-old NOS pair of 2A3's. :tears:

Thanks. That is what I thought. When I was a kid I had an electronic experiment kit (board). One of the experiments was to drive a germanium transistor to avalanche conditions and listen to it (as it failed). The instructions never mentioned ruining the transistor. I guess all the other kids that had one of those kits grew up to be guitar amp builders.

I will try to get a picture, but, it is a black "top hat" with a prominently displayed GE logo. I forget what base that is called now (TO-???).

I believe the 2N2712 (a silicon transistor) can be used in reverse biased EB junction
avalanche without arm. An old article in Popular Mechanics (Build a Pink Noise
Generator) described that many years ago.

P.S.: actually in Popular Electronics. Sorry about the mistake