Best if any way to identify random diodes?

rwgast_logicdesign

So this part trade I just did was very cool, got alot of neat stuff! Most of it is either packaged or labled with part #s. But I got this bag of glass diodes

There are a few different looking ones, I took a few to a meter and they all had random Vf voltages anything from .2 on both leads and out of range or 0 on both leads to .5 on the anode only, obviously this is a mix of zeners and other stuff, im really hoping to find some fast switching 1n4148s in here as I seem to need those the most. Is there any way to figure out what these are so I can use them, there is no code stamped on any of them checked under a magnifier

LoopyByteloose

First of all, sort everything by similar package.

I suppose you could check forward and reverse voltages for each and every one and group the ones that are alike together. At some point, it may become very clear what is what.

Have you tried a 20x jewelers loupe to read labels? A magnifying glass may not be adequate.

Frankly, 1n4148 diodes are cheap, so are 1n914s. All this is seems to be very low wattage if they are zeners, 1n4148, or 1n914. Do you really need to put that much effort into them? After all, if they end up being a pile of various zeners, how often do you need zeners? And are these the right zeners in both voltage and wattage?

If they are 1n4148 or 1n914, they should effectively have no conduction in one direction to (Vf between 0.62 and 0.72, while Vr is 75 volts or more). They do have bands on them that should tell you if you are measuring Vf or Vr. Those bands should easily help clarify if they are zeners or regular diodes.

Some 1n914s do have colored bands.

I strongly suspect that they are either 1n4148s or 1n914s as the zeners are more likely to have actual numbers labeled on them.

Sorting glass zeners by Vf and Vr is likely to drive you nuts (see reference material below). These may have a 47 on them as they are 1N47xx zeners.

http://www.vishay.com/diodes/zener-stabilizers/do41-package/

kwinn

Here is a simple tester you can wire up in a few minutes to check the diodes. Measure the voltage across the diode in both orientations. A signal or rectifier diode will usually read the same voltage as your DC supply when connected one way and 0.2 to 0.7 volts the other way. A glass encased diode usually means it is a signal diode and 0.2 to 0.4 is typically a germanium diode, 0.5 to 0.7 a silicon diode.