(cool link alert!) History of UK transistor development

[dai h.]

nice Brian!

not quite sure if this link should go here but since it does contain pictures of parts and logos, maybe okay? (If not please move it at your discretion.)

anyway, found a cool link with some history on UK transistor companies including Newmarket, as in "NKT275" (the "Fuzz Face transistor") by Andrew Wylie who has apparently done a bit of research into the history of semiconductor manufacturers:

http://homepages.nildram.co.uk/~wylie/h ... indust.htm

I also noticed this passage which I thought was kind of funny:

The range NKT200 - NKT299 is described in the Portfolio as comprising germanium alloy PNP AF transistors, in TO-1 and TO-5 packaging. I possess a number in those standard cans, but also have several types in the oval SO-4. For reasons that are mysterious to me, one type in this range, the NKT275, seems to be regarded as the 'holy grail' of germanium PNP transistors by people who build guitar effects units using 1960's circuits. In terms of its characteristics, this is quite a poor device, with low collector-base voltage and a wide spread of low gains. I have been a huge fan of Hendrix since his first album, but I can't help thinking that he would have embraced new technology rather than slavishly copy obsolete circuits.

http://homepages.nildram.co.uk/~wylie/NKT/newmarket.htm

there is a bit more on the early US semiconductor industry and a page on early US manf. logos, but the UK ones have the most content:

http://homepages.nildram.co.uk/~wylie/h ... indust.htm

http://homepages.nildram.co.uk/~wylie/history/logos.htm

don't forget to check out his links page as well:

http://ourworld.compuserve.com/homepage ... /links.htm

which has some cool links such as to here:

http://www.electricstuff.co.uk/oldadverts.html

[David B]

For reasons that are mysterious to me, one type in this range, the NKT275, seems to be regarded as the 'holy grail' of germanium PNP transistors by people who build guitar effects units using 1960's circuits. In terms of its characteristics, this is quite a poor device, with low collector-base voltage and a wide spread of low gains. I have been a huge fan of Hendrix since his first album, but I can't help thinking that he would have embraced new technology rather than slavishly copy obsolete circuits.

Jimi seemed to like them OK though he did move on to silicon ff later on , wonder if those old Newmarket NKT's have a a unique tonal character compared to other brands?



thanks for the link

[dai h.]

probably hard to test since I suppose you'd have to get a working NKT unit to compare to, then match it with other brands. My guess is that you could match with some brands but some might be slightly different. Compared to (subjectively) the "best" (to my ear) ones (Matsushita) some of the brands (working, in spec for gain and leakage) seemed a bit different in sound (NEC, Toshiba if mem. serves). One the types (NEC 2SB163) had steel leads and I wonder if that makes for a tiny difference (are magnetic and some parts marketed for audio as well as some lit. touts benefits of non-mag. copper over magnetic steel leads). Overall though, not having the exact original types doesn't seem to be a hinderance to coming up with a good sounding FF IMO.

[Brian Wallace]

Very cool reading Dai. Have you measured any of these transistors for their HFE(Beta) values?

[dai h.]

hey Brian. Yes I did according to the info at Small Bear, which I think is basically 1) measure leakage, 2) measure gain, then 3) subtract leakage from gain to get the "true gain". Some had weirdly low leakage and high gain but I found some info recently that those were low noise transistors, so maybe that makes sense (Toshiba 2SB440 and 257? if mem. serves). The selected ones were a substantial improvement to the stock AC128 (E.Euro?) in my Roger Mayer Classic Fuzz (basically a FFace with bit different values). The ACs were real leaky and had too much gain.

[David B]

my readings with some Matsushita S2B324 all low around 50hfe, 172 & 175's anywhere from 70 to 150 and most surprisingly little leakage ..measured with Keens apparatus.. Yes the Matsushita properly matched sound great. Also have some Phillips OC76 but most like like a sieve and hfe in the 150's up..

[dai h.]

from what I remember,

(ones I had in quantity from 50-ish to 100, 300uA max. leakage)
2SB32 poor yields, mostly low gain
2SB163 not bad mostly gains good for Q1 (80-ish)
2SB172 high yields for Q2 (120-ish)
2SB167 poor
2SB415 poor

some of the readings from a couple of the 2SB422:
leakage 129uA, gain 298
134uA, gain 328.4
68uA, gain 106.4
39uA, gain 99
2SB257:
leakage 65uA, gain 112
74uA, gain 154

AC128
Q1 (I have written "1.4 to 1.6", so I guess mA), gain 204
Q2 leakage 453uA, gain 108