Diode identification

[Chillums]

Hey everybody... I'm new to the site so I'm not sure if I'm posting in the right place but I got a handful of these diodes from my grandfather's house and they have no markings on them... Just black and blue.  Anybody know what these are?  Ill try and post a picture because I know black and blue is very vague.  Thanks in Advance

[GibsonGM]

If you take a magnifying glass and look closely...can you see any numbers on them?

Welcome to the site, you're absolutely posting in the right place

[arkatom]

Yeah without any markings it's going to be hard to tell what's what.


Sent from my iPhone using Tapatalk

[antonis]

Black & Blue mostly indicates Zener diodes..
(Black is Cathode, as usually..)

They should have a 500 - 700 mV forward voltage drop (as for ordinary silicon diodes) but you can't verify their reverse brakdown voltage with a multimeter because of instrument's very low current..

If you have an adjustable power supply up to 25V, at least, to cover the commercially used zener range, place in series with PS (+) out a current limiting resistor of, say 100R, with zener cathode facing to resistor and anode to (-)..

With Voltage knob initially ALL THE WAY DOWN (a PS adjustable to 0 Volts with a multi-turn Voltage pot should be desirable..) start VERY SLOWLY to increase PS out voltage, continuously monitoring voltage drop between zener's cathode and anode..
(multimeter's Red lead on cathode & Black lead on anode/PS(-))..

When zener voltage drop is stabilized (no more rise for, say 1V or 2V, PS Voltage increase) stop and lower back PS out voltage, to avoid any zener/resistor overheat due to possible over-power dissipation, and mark that voltage for respective zener..

P.S.
A variable Voltage PS with precise Current limiting should be ideal for that job but the possesion of such a benchtop instrument assumes some degree of involvement with electronics and consequently knowledge of zener diode function & testing.. 

[Kipper4]

Didn't mr Lyman have some caps that looked a bit like that?

[Cozybuilder]

I have some BAT 41's that look like that.

[Ice-9]

There are lots of black and blue diodes around. for example I have plenty 1N914 and even 1N4148's can be this colour, lots of BATxx are this colour as are many zeners, this colour does not mean it IS a zener although it could be. They should have a number on them so have a look at this first as the clue is usually there.

Although they are a little unusual in having the colour marking 50/50. Is there any lettering on them at all ?

[Chillums]

Hey everyone... Thanks for all the input.... I've been looking under the micoscope and can't seem to find any numbers or letters on it... The forward voltage is  around .575 if that helps any.... Would be cool if they were bat41's.  Thanks again for all the help.... I'll try and get a variable PS to test if it's a zener later this week.  Maybe by then someone will have a  better idea..... Love this site!!!

[bluebunny]

Does it matter what they're called?  Just breadboard something that has diode clippers (for example) and tweak yourself a circuit where they sound good.  Then call it the Black'n'Blue overdrive.   

[Chillums]

I like how you think