Fake 1n34a germanium diodes on tayda?

[Intense_wizardry]

Just ordered in a bunch of 1n34a diodes and ran across a few people online saying the ones on tayda are fake. I'm confused on this because tayda advertise them as DO7 size, which is now only used for germanium diodes, I have no idea what to belive but this has got me worried. If any of you could shed some light on this I'd be really grateful

[GibsonGM]

You can tell for sure when they arrive by finding the voltage drop across them...that should be about .3V.  Typical silicon diode would drop about .5v or a little more.  If your meter has a 'diode test' function, that is what it is for. 

I haven't heard anything about fake Ge's from them.  I'd think that due to the ease of identifying them this way, they'd avoid that, LOL...

[Intense_wizardry]

Thanks for the quick reply, I'll be sure to check the drop. I thought that them being fake was a bit off from the fact that they're in do7 casing but some guys on another forum were badmouthing them, but as you said, it would be pretty bold for a company like tayda to sell counterfeits

[armdnrdy]

If I recall correctly...there was a problem with Tayda selling 1N60s listed as germanium.

The diodes Tayda was offering were a D0-35 package.

It turned out that there are two 1N60s. One is a germanium, (D0-7 package) and the other in the
DO-35 package is a schottky.

Honest mistake.

[Intense_wizardry]

If I recall correctly...there was a problem with Tayda selling 1N60s listed as germanium.

The diodes Tayda was offering were a D0-35 package.

It turned out that there are two 1N60s. One is a germanium, (D0-7 package) and the other in the
DO-35 package is a schottky.

Honest mistake.

thanks for clearing that up, are the DO7 diodes that I ordered likely to be 1n60s instead of 1n34a? And will that make a difference for use as a clipping diode?

[armdnrdy]

The diodes you have are germanium.
If they are actual 1N34As.....that's difficult to tell but...it doesn't really matter.
Germanium diodes should have a similar forward voltage drop.

[Intense_wizardry]

Right, thanks for the info. Glad to hear I haven't wasted my money!

[Fast Pistoleros]

Tayda is legit - their engineers pull stuff out of stock or will refund if you have any fake parts.

[Scruffie]

I've read they're legit (the proper way to test will be if the fV changes with temperature from a finger or lightbulb or something) but that they're very brittle so take extra care bending the legs.

[Mark Hammer]

Why on earth would anyone "fake" 1N34 diodes?   That's like counterfeiting pennies.

My own experience with germaniums is that their Vf can be all over the place, from 200mv up to 350mv.

[teemuk]

My own experience with germaniums is that their Vf can be all over the place, from 200mv up to 350mv.

Basically their entire forward characteristics can be "all over the place".   

This is what we generally assume of silicon vs. germanium:

Basically germanium has forward voltage of about 300 mV and "softer" transition to forward bias than a silicon diode that has forward voltage of about 600 mV.

Here is a sample of reality:

Both OA5, 1N34A and AA112 are germanium diodes. 1N34A has forward voltage of about 300 mV but it's characteristic curve isn't actually much different than that of a generic silicon diode. OA5 has about similar transfer characteristics, yet forward conduction at about 100 mV lower voltage threshold. The AA112 is entirely different: Characteristic curve slopes more gradually and while forward conduction starts around 200 mV the forward voltage spans much higher than with generic silicon diodes. It's actually the only "soft clipping" germanium diode portrayed in the graph.

The graph doesn't portray many examples of silicon diodes but simply a quick glance shows that forward characteristics in each category - whether germanium, silicon, schottky, or selenium - actually vary quite a lot in practice. Both in forward voltage and overall "slope" of the characteristic curve.

[blackieNYC]

Hey, let's be careful with those subject lines!

[Bill Mountain]

I have purchased them and while I can't confirm if they are fake, I can confirm some of them didn't sound right in a distortion circuit and the forward voltage on some was as high as .6V.

Test them yourself.  I know for myself I will try and buy NOS in the future so I can compare.

[Mark Hammer]

Well Teemuk's post suggests that, to some extent, one can massage the performance of Ge diodes (at least those going to ground) via the series resistance setting the current they are being fed with.  Is that a reasonable assumption?  That is, normally see something like 10k in series with the signal and a pair of Ge diodes to ground after the 10k.  And if it doesn't sound "right" we assume that the problem is the diodes.  Maybe the problem is the mismatch between specific diodes and the specific current-setting resistance value?

[pinkjimiphoton]

The diodes you have are germanium.
If they are actual 1N34As.....that's difficult to tell but...it doesn't really matter.
Germanium diodes should have a similar forward voltage drop.

if you have a jeweler's loupe, they actually say 1n34a on them

[Mark Hammer]

Some will, some won't.  Same thing with Si diodes.  Some will have a component number printed on them and some will be so small that there's no room.  A friend brought me back some of those 1S5558 or whatever Si diodes that Boss uses, from Japan.  And I'll be damned if I can find them in my parts drawer because they have nothing printed on them.