1N4148 - Anything better?

[JimB]

Come on you old codgers, get with the programme!

12AT7 = ECC81
12AU7 = ECC82
12AX7 = ECC83

Having said that for most applications any one of the three (six ?) will work at a push.

JimB

 

[mvs sarma]

Hi, Sorry for asking unrelated thing, but why you match set of 6 and manage 14 sets? Confused what you were saying.

And from were you bought part from ebay and from where they delivered to you there in India? Maybe was expensive.

i was making few antenna analyzer test instrument. the circuit demands the diodes to be matched.

 

[MaxHeadRoom78]

Because it's only ever American members here who make such suggestions - ).

I was born British and spent the 1st 35yrs there, now Canadian, so not sure what bracket I am in?
BTW I have been using the 2n7000 since its introduction by Siliconix in the 80's.'
Maybe something from the neighbor has rubbed off!
Max.

 

[Tony Stewart]

This one is the gold standard for small signal general purpose silicon diodes. Special purpose diodes will enhance one parameter at the expense of another. By comparing every variation (suffix) and OEM specs, you can discover a lot of rules of thumb , common to all diodes and unique variations between packages and OEM within the 1N4148 family.

Variations of 1N4148

• Lower current ratings more like the 1n4448, now a suffix variation of 1N41418, the junction capacitance @1MHz drops from 4pF max to ~2pF max and is 0.56 pF typ. @ 0V
• Each vendor, specs the Imax continuous from 100mA to 300mA depending thermal resistance to ambient. In some cases Diodes Inc spec. 300mA with 4 sq.in. of 3 Oz double sided copper.

Common parameters not shown in datasheets

• The dynamic resistance , becomes fairly flat (ESR) , when the diode is saturated, often limited by the current and thus thermal limitations of the tiny insulated whisker anode wire and junction conductor size. This is true for all diodes and there is a point near the end of curve where the incremental Λ V/I , resistance or ESR is equal to the inverse continuous power consumption in Watts. In this case at 25C 400mW => 2.5 Ω going down to 1 Ω at 1V. This is only a straight line on log-log or lin-lin (linear) graphs of V vs I when the diode is saturated.
• The pF value @0V and ESR @ Imax continuous are inverse related so the product is called a figure of merit FOM , just as it is for MOSFETs.
• All semiconductors can be used as varicaps using Reverse bias, but special purpose varicaps are processed for tighter tolerances like 25% and wider C ratios at V1/V2 and one company bought by Delphi for over a billion$ for its RF technology and hundreds of patents one of which (patented before Y2K) use this feature for tuning resonant antenna in its RF remote controls for cars used in garage door openers in the VHF range. With inhouse custom binning, we brought this tolerance down to 1% for using varicap properties at 1 GHz for TC-VCXO use at 1ppm using standard 50ppm Xtals sorted by a 15 second test at 40 to 70'C ppm linear offset on a 3rd order characteristic.

All wirebond bonds are made of micron sized gold wires to prevent metal diffusion contamination of the semiconductor. But Diodes Inc have adopted the use of copper since 2008 in this part, perhaps with improved passivation or wire Au microplating.

At any time you can expect over 1 million devices in stock at Digikey, of all 1N4148 types, more than any other diode and cost less than a penny in OEM volume agreements.



The 1N4148 is also known as (aka) the BAV16, better known to our European friends. Each suffix denotes family and package variations. Keep this in mind when multi sourcing and relying on parameters discussed above.

 

[Nigel Goodwin]

Come on you old codgers, get with the programme!

12AT7 = ECC81
12AU7 = ECC82
12AX7 = ECC83

Having said that for most applications any one of the three (six ?) will work at a push.

JimB

To be honest I've never been bothered enough to remember which was equivalent to which

But they are pin compatible, and you can drop any in (at a pinch), and while not optimum it can often get you out of a hole.

However, and rather sadly, I can still remember the pin connections - a, g, k, h, h, a, g, k, h-ct

 

[crutschow]

And 2N3904's and 2N3906's... but curse the fact that people still want to use LM741s and 2N3055s.

An what's wrong with the 2N3055?
It's a tough old bird that's still good for some DC and low frequency power applications.

 

[MikeMl]

Certainly wouldn't be - as a 12AX7 is an American valve

If you'd said ECC82 or similar, you might be closer.

The Brits are so self-centered that they had to put their own numbers on common parts...

 

[MikeMl]

Come on you old codgers, get with the programme!
...
JimB

And they cant even spell.

btw- this is written by some whose native language is not English (or American), who is married to a Canadian...

 

[MaxHeadRoom78]

And they cant even spell.

.

Programme.
Maybe aimed at the French Canadians?
Max.

 

[Tony Stewart]

2N3055' are cheap 100W+ linear active loads that can be used with heatsinks for active load testing for a buck (~1$us) in volume and much cheaper than fixed R power resistors of same rating.

But then 100x worse for conductance Rce vs RdsOn than a 10mΩ MOSFET of same cost as a switch.

I was often fascinated by the modulating blue plasma from the 12AX7's of my BOGAN stereo. But then spare parts were stocked at a nearby drugstore with tube tester. Circa late 70's. now the only testers there are for blood pressure.

 

[Tony Stewart]

Programme.
Maybe aimed at the French Canadians?
Max.

Max , do you live near the N.American geocentric St Boniface of Winnipeg, my home town where J&J's was like a little version of Fry's , a silicon valley store famous for parts and surplus.

 

[JimB]

Program is programme in English, except when it is a computer program, then it is program.
I think my brain just exploded.

JimB

 

[MaxHeadRoom78]

Max , do you live near the N.American geocentric St Boniface of Winnipeg, my home town where J&J's was like a little version of Fry's , a silicon valley store famous for parts and surplus.

Yes.
The only local parts store now is Tip Top Electronics.
Max.

 

[Tony Stewart]

Program is programme in English, except when it is a computer program, then it is program.
I think my brain just exploded.

JimB

Aye laddie, it's good we don't use Gaelic or Cantonese for programming and html.

Thanks to the lowly silicon diode CPU's can measure and report its own core temp's.

 

[MaxHeadRoom78]

, my home town where J&J's was like a little version of Fry's , .

You may be interested in this.
http://www.marionharding.net/id14.html

J. & J. Electronics founded in Winnipeg Canada and London, England in 1964 was one of Canada's pioneering electronic companies. It sold to individuals, institutions and the armed forces across North America until the 1980's and maintained excellent working relationships with companies including Fairchild Semiconductors. The company was named after its founders Antony John Harding and Joshua Raphael the latter who had come from a long line of Jewish Egyptian silk merchants whose entire family John Harding was legal counsel for in England. John and Joshua set up the company when John moved to Canada with Marion as he had a sound grounding in electronics as a result of his Royal Air Force training in radar. John Harding initially worked as Business Administrator for the Winnipeg Art Gallery in 1964. As can be seen from the 1976 catalogue cover Marion not only worked for the company but was responsible for its aesthetic image and public relations.
Max.

 

[Tony Stewart]

Fascinating. I now see the connections now between RAF Radar, Legal expertise, software and electronic parts

Funny...... What you need to know about ...Tax and other nasty things...

 

[MaxHeadRoom78]

Funny...... What you need to know about ...Tax and other nasty things...

The funny looking black square in the centre may puzzle some!
Max.

 

[gophert]

The funny looking black square in the centre may puzzle some!
Max.

... And the black rectangles above them and the weird things between the keyboard and monitor and the things on the bottom that look like tissue boxes with paper popping out of the top.

 

[maicael]

Interesting conversations.
Well I wanted to clarify something about protecting MOSFETs from back EMFs generated when switching inductive loads.
Now I know that a MOSFET has an internal body diode by design but I want to know if I can add an external diode from source to drain and if so my questions is this
1) is it source to anode and drain to cathode?
2) can I use an ordinary diode in place of of a zener?

 

[Tony Stewart]

1. No, unless it is push pull.. the diode goes across the inductive load in reverse of normal direction, rated for same current and forms a smaller current loop.
2. No, unless just used at low rates as all diodes have capacitance.

Depending on speed diode must be a fast recovery type Schottky. The normal Body diode unless a zener does not protect for overvoltage because the diode is in reverse connected to Drain instead of V+ for low side switch.