What's the difference between FETS and JFETS?

[humbuck]

Well, the subject says it all.

In the old days we used to call 'em FETS (Field effect transistor)

But what the hell are JFETS? :?

H.

[Brett Clark]

FET is the more general term.

JFET is Junction Field Effect Transistor, which means the gate is isolated by a reverse-biased PN junction. This is the most common type of FET.

The other main type are MOSFET's (Metal Oxide Semiconductor FET). In these, the gate is isolated by an insulating layer of metal oxide.

[humbuck]

Thanks for that

I've never come accross the term "JFET" before! How strange is that!

Cheers,

H.

[Brett Clark]

It must be a difference in tech jargon between UK and US  - - I almost never use "FET" without specifiying what type.

Some folks even refer to valves (tubes) as "Vacuum FET 's". Which they are, of course.

Hey, I'm looking for some of the round Bulgin 3-prong "pignose" plugs that fit in the back of the old Marshall amps. They're almost impossible to find over here. Can you still get them in the UK?

[gez]

Hey, I'm looking for some of the round Bulgin 3-prong "pignose" plugs that fit in the back of the old Marshall amps. They're almost impossible to find over here. Can you still get them in the UK?

Can you post a pic?  Not too sure what you mean.  Everything is standardised over here now so if they're old 60s design or something I doubt it, but you never know.  Show us what you mean and maybe some of us overhere can help (might be one stuck on the end of an old toaster or something!)

[petemoore]

The newer amps have these...so you can disconnect it and don't have to wrap the cord around the amp.
 Same thing they use on Computer power supply cords.
 If you look at it square it looks like the shape of a pig snout.
 I have many of them here, one in the car, one for the amp another for the Eon monitor, plus a buncha spares in the basement "PC Collection room"...they come with the free monitors and puter frames...
 Very common around here these days. I got one from a music store, had to trim the thick plastic at the end so the prongs go in far enough...[I HATE PS issues when they're connected to output sections!!!]...fixed it right up!

[Brett Clark]

Thanks, Pete, but that's not it  - what you are describing is an "IEC" connector - pretty easy to get anywhere

What I need is called (among vintage amp folks) a "pignose connector". It's round, about 1"/25mm in diameter, with 3 round female pin connections. They were used on British amps from the 60's .

[toneman]

yes,
but they R *rectangular* not round.
the old *oval* ones went away with the old waffle irons.
though i still have one on my Conn Strobotuner.
AFN
tone

[Hal]

wow this topic changed a lot :-D

Kinda back on topic: what the heck are HEXFETS?!?

I've seen them for sale, but have no idea wha they are...

[Boofhead]

HEXFETs is just the family name for MOSFETs of a particular construction made by IR (International recitifer).   At the end of the day it's a MOSFET.  The details of MOSFETs can be bent around a bit to provide certain characteristics, companies who do this stuff come up with new ideas and give the process/structure for the MOSFET a family name.  You will see a lot of that type of thing with MOSFETs - the process name thing actually occurs with normal transistors (BJT's) as well but it doesn't get such a big plug marketing-wise.

You have to be careful whether the name is a marketing name or a real semiconductor structure.

There's things called MESFETs which are sort of JFETs but the difference is enough to warrant a new name.

[Paul Marossy]

FET is a loosely used term, but it seems that when most people say "FET", they are referring to a JFET.

MOSFETs are usually referred to as a MOSFET.

[Brett Clark]

yes,
but they R *rectangular* not round.
the old *oval* ones went away with the old waffle irons.
though i still have one on my Conn Strobotuner.

What I'm looking for are DEFINITELY ROUND. Marshall didn't change to the rectangular type (IEC) until much later. And they never used the little oval ones ("waffle iron" type, as you say) at all, that I'm aware of.

Sorry to get this topic so far astray - it's just that there were some UK folks following this topic, and I thought they might be able to help

[smoguzbenjamin]

Hah, try makin my dad read this. When he studied electronics he got taught that FETs were useless and that tubes and bipolars were the bee's knees. Lol he still believes that today :lol:

[Sic]

bee's knees...

LOL haven't heard that one in a while.

I'm from england but live in the USA...

My dad loves saying "The bee's knee's" and "The dog's bollucks"


Gotta love having so many backrounds and cultures around here... helps keep things in perspective.

[Sic]

Btw


Bee's Knees and Dog's bollucks means: the best, bad ass, awesome, etc etc.