Germanium Diode Data sheets

OK, that makes sense....

Is there any reason to choose 1N34 versus 1N60, or will both work equally? Of the schematics I have, both were used.

I have to buy some either way, but they are cheap on ebay, like 10 of them for around $2.50 so it's no big cost. I just need to determine which one to buy. (Or the 1N270 are also quite available too).

Because germanium diodes have a lower voltage drop and are more sensitive.

The 1N34 series is very often used in crystal radios - that should indicate the 'why' as compared to silicon diodes. It has to do with sensitivity at very low voltages.

There are silicon-based probes today, but germanium for the sensitivity is still preferred.

Peter Wieck Melrose Park, PA

ate the 'why' as

ltages.

is still preferred.

As I understand it, a 1N34(a) is a bit more rugged than a 60 and has a bit more voltage headroom before it clips (drops off) - but that in 80% of most applications, either will be fine. That is 100% second hand, and not from experience. I use the 34-series almost exclusively for this sort of thing a nd have at least 20 on hand at any one time, they are so cheap.

Peter Wieck Melrose Park, PA

That's why there are spec sheets - you need to figure out which one fits your application best. If it doesn't really matter then just get the convenient one.

John :-#)#

Thanks for the info. 1N34 is one of those numbers I never forgot. Even though I was pretty much out of electronics for near 40 years. Just like tubes, I remembered certain ones, like 6L6 6V6 5U4 6SN7 12AU7 12AX7, and the ones in the "american five" radios like 50C5 35W4 etc. So, when someone says Germanium diode, 1N34 comes to mind first....

I guess from what you said, they were used more than I thought.

I have never used a Schottky diode, but I heard of them.

If I could view that chart I downloaded (PDF) showing all the germanium diode numbers and characteristics, I'd see which of them had the higher PIV (between the 34 and the 60). But my PDF reader is broken, and will probably take a few hours to download again on dialup.... But I do think the 34 was the higher one, and if thats the case, that is what I will buy and use. I think they are a few cents cheaper too, but it's so small amount that it really dont matter.

The 1N34 was available to hobbyists early, probably because Rufus P. Turner was connected to its development.

Realistically, what's being referenced is a germanium diode. The part number was a descriptor, when you saw it you knew it was a germanium diode, and that was really all that mattered. The number kept being used because it had been used, and diodes with that number were available through hobby outlets. I have no idea if they were all 1N34s, but they would have all been germanium small signal diodes.

For the hobbyist, it didn't matter. They'd be used for "crystal radios", field strength meters, rf probes, and maybe diodes in the detectors of superhet receivers. It was never a fussy thing, except that they be germanium. I guess the 1N82 was germanium, seen in UHF tuners as a mixer, and used in such hobby projects where a high frequency diode was needed, like crystal radios intended for the aircraft band. So I guess a lot of UHF tuners in the old days had a germanium diode in them. I found a bunch in the FM detectors of various FM broadcast radios, at a time when I would have though silicon had taken over, indeed transistors in the same radios were silicon.

Because the germanium diode has a lower forward voltage drop.

Schottky diodes have lower forward voltage drop than silicon, though I can't remember if it's lower than germanium. A DMM with a diode function will easily separate them, all three diodes have a distinct voltage.

I went through a bunch of boards at one point, and uncovered a lot of germanium diodes this way, certainly more than I expected.

Michael

Schottky diodes have lower forward voltage drop than silicon, though I can't remember if it's lower than germanium. "

I think they go lower in forward drop, but I am not sure how they are with RF. They were used quite a bit in SMPSes but that doesn't mean you can ju st hook them up to an antenna and pick up WKRP in Cincinnati. But it does s eem logical they could. I think the capacitance is an issue, an SMPS can pu nch though that no problem, a long wire antenna not so much.

Germanium has alot of problems, and one of them is temperature. They can on ly go to 100C whereas silicon can go to 200C. That is a whole different der ating factor there, only half. So some silicon diodes are much better despi te the voltage drop.

All this shit is only useful in very low level stuff. Nobody with half a br ain would use a germanium diode or transistor in a modern design unless the re was good reason. The last time I heard about it was Phase Linear, Bob Ca rver used germanium transistors in the current limiting circuit. I know bec ause I had to deal with it a few years ago.

Also, there is a guy on here that wants to fix a bench power supply that us es germanium a transistor for current regulator. I would like to help but I am not quite sure what to do. There is a diode in the circuit which would have to be replaced, and then the circuit must be redesigned for the silico n transistor. I only saw a partial print of it, ad really though I can get the current limiting and whatever working, it would not be calibrated. Germ anium is funny stuff. I is much different to what I am used to these days.

And, then there was the 1N21 -- a germaniun diode built in a form factor to facilitate its use in microwave tubing. Handled a lot of them maontaining the MG-10 radar system on the USAF F-102 Fighter Interceptor in the 1960's.

Jonesy

Sounds good to me!

Go with the 1n34A as it has about 3 times the voltage break down as the

The germanium has a junction voltage of about .3 volts and the silicon .7 volts. Better sensitivity at low voltages.

(Mumble) years ago, I needed some germanium diodes for an amplifier I was designing (it was the conduction drop over temperature I specifically needed, for thermal compensation). Found some 1N34s in a catalog, and ordered a few. Which didn't work.

Took a while, but I finally got data sheets and (by that time) was not very surprised to find specs of 0.7V forward drop and tempco matching silicon, not germanium.

So in answer to your question, I'd say some of them do.

Isaac

AAZ15 Ge 0.11V @ 50uA

BAT46 Schottky 0.15V @ 50uA

MBR745 Schottky 0.12V @ 50uA.

That last diode is rated at 7.5A, the other are all small signal types.

.... Phil