Germanium SMD ?

[60 oldjohn]

Are Germanium diodes available in SMD ?

John.

[G6Tanuki]

Not that I'm aware of; Germanium diodes have - irrespective of encapsulation - almost entirely been replaced by silicon Schottky diodes.

[Nickthedentist]

Are there any germanium diodes currently made?

[60 oldjohn]

Originally Posted by G6Tanuki

Not that I'm aware of; Germanium diodes have - irrespective of encapsulation - almost entirely been replaced by silicon Schottky diodes.

Thank you, looks like I will have to form J leads on a TH device and mount on copper side of PCB.

John.

[60 oldjohn]

Originally Posted by Nickthedentist

Are there any germanium diodes currently made?

I don't know, but SMD have been around for 35 years or so, maybe ONS part?

John.

[ppalped]

Originally Posted by Nickthedentist

Are there any germanium diodes currently made?

The 1N34A was still being manufactured until a year or so ago by NTE but it seems that is no longer available, at least for the time being.

It seems that NTE is still manufacturing some Germanium diodes (but none of them are in a SMD package):

https://www.nteinc.com/diodes/general-purpose.php

Alex

[David G4EBT]

Originally Posted by ppalped

The 1N34A was still being manufactured until a year or so ago by NTE but it seems that is no longer available, at least for the time being.

Alex

1N34As are plentiful from reputable UK suppliers on eBay - typically £2.95 for ten or £4.99 for 20 post free. (not SMD of course).

I’ve used them for years as standard replacements for OAxx on radios such as Roberts.

[factory]

Aren't NTE parts just relabelled old stock, for the obsolete parts?
Someone elsewhere commented most new parts advertised as Ge diodes are just relabelled Si parts.

As for Ge parts still just about available, there is a strange hybrid of Si/Ge in these SMD diodes from Mouser; https://www.mouser.co.uk/c/?q=germanium%20diode

David

[ppalped]

Originally Posted by factory

Aren't NTE parts just relabelled old stock, for the obsolete parts?
Someone elsewhere commented most new parts advertised as Ge diodes are just relabelled Si parts.

As for Ge parts still just about available, there is a strange hybrid of Si/Ge in these SMD diodes from Mouser; https://www.mouser.co.uk/c/?q=germanium%20diode

David

Can't confirm or deny this, but for the supposedly Ge parts I used so far from NTE, they trace identically or extremely close to the originals. I doubt they manage to get Silicon parts to behave like that, but if they do, then it really doesn't matter as long as the in-circuit behavior is identical to the original.

PS: The biggest downside of NTE is that the components are usually very expensive, so I tend to use it as a last resort.

Alex

[David G4EBT]

My Hameg 203-7 'scope has a built-in component tester which - among other things, identifies whether a diode is silicon, germanium, zener etc. Something of a luxury perhaps, but handy, nevertheless.

Pic 1: Germanium.
Pic 2: Silicon.
Pic 3: Zener.

[factory]

How do Schottky compare with Ge on the Hameg? Leakage current seems to be another way to check.

Originally Posted by Nickthedentist

Are there any germanium diodes currently made?

Farnell have a 1N270 which claims to be Ge, Mouser claim it's obsolete.

https://uk.farnell.com/solid-state/1...o-7/dp/1862942

David

[60 oldjohn]

Originally Posted by David G4EBT

My Hameg 203-7 'scope has a built-in component tester which - among other things, identifies whether a diode is silicon, germanium, zener etc. Something of a luxury perhaps, but handy, nevertheless.

Pic 1: Germanium.
Pic 2: Silicon.
Pic 3: Zener.

Hi David, That is one way to test, I look for a 0.3v voltage drop against 0.7 for silicon, I have plenty of diodes with rubbed markings. If I do get it wrong the circuit wont work as it is supposed to, it is not going to blow anything up in this low powered circuit.

John.

[Radio Wrangler]

You'll find SiGe silicon-germanium compound diodes in SMT. Also transistors. They're a sort of halfway house to Gallium-Arsenic semiconductors, more speed for not much more price. Specialist RF devices cheaper than GaAs.

David

[Maarten]

It seems SiGe diodes have the same high voltage drop as silicium diodes.

[Keith956]

Originally Posted by Maarten

It seems SiGe diodes have the same high voltage drop as silicium diodes.

Actually they have a Vf typically ~0.15V less than silicon; the bands of a SiGe junction is tuneable according to the Si - Ge ratio. They are found in power supplies (although only relatively recently) where lower Vf equals less drop, and hence higher efficiency. Compared to schottky diodes they have much better reverses characteristics e.g breakdown voltage and leakage.

[Maarten]

That makes sense. I always thought they were going the siliciumcarbide route for improving the breakdown voltage of Schottky diodes, but it never hurts to have some alternatives.