ID unmarked diodes by metering

[Reeltarded]

I have some overbuilt industrial bridges with unmarked diodes on them. They read .475 on my meter.

How do you identify these things? I'd like to use a quad of them as a tube replacement but I am unsure how to evaluate what can work. I am used to usng 4007 series, but apparently I'm all out of those. (and chewing gum.. )

They are massive. Back with a pic.

[Reeltarded]

Shown with a pair of 1N4007 I used in a clipping circuit.

[sluckey]

The only way to determine if those diodes will work in your application is to examine the circuit they came from. You can't just look at the physical size and determine voltage/current ratings. You can probably say that the larger diode has a larger current capacity, but size will tell you nothing about the voltage rating. Those diodes could be rated for 1000V but they may only be rated for 50Vpiv. Need to see the circuit they belong to in order to determine if they are rated sufficiently for your intended use.

[Reeltarded]

Fine. I'll hook them up to the pole across the street before the transformer and lick them to see if I taste at least 1000v.



These 1000v 10As measure .492.. a pair of these per side works?

[R.G.]

Physical size in a diode has more to do with current rating than voltage rating, which is a big deal for what you say you're going to do (quad as a tube replacement), That's because silicon diodes have a slightly variable voltage when conducting, from 0.5V at really low currents up to a volt or so at high currents. The actual standoff voltage may be anything, and you can't tell without a data sheet until you actually break the diode with reverse voltage.

Also, those may be Schottky diodes. Same comments, but they tend to have half the voltage of normal silicon diodes for the same current, and that's why they're used. Germanium didoes are lower yet, but rare as hen's teeth in high currents, and not in those packages.

Bottom line? If the circuit you're going to use them in would be damaged if the diodes couldn't handle the voltage, bite the bullet and order high voltage ones, or prepare to see smoke. Sorry, devining voltage rating isn't easy.

[Reeltarded]

damn y'all stop pooping on my parade

These look like NASA sercret project diodes. Marked MIOA MIC. I bet aliens.

[pompeiisneaks]

If you have plenty to spare, you could put em in a circuit with a super high watt resistor and see how long it takes to burn em up (Nothing else in the circuit of course) FIRE FIRE

~Phil

[Reeltarded]

If you have plenty to spare, you could put em in a circuit with a super high watt resistor and see how long it takes to burn em up (Nothing else in the circuit of course) FIRE FIRE

~Phil

This is serious and dangerous. This is not the time to be joking around.

[pompeiisneaks]

I was only joking about the fire fire part. The rest is a test that people do on a regular basis with controlled environments to see the failure mode of things. You obviously expect it to burn up, and need to have precautions set to avoid fire and easily shut down the circuit etc. Yes it is dangerous, but not more dangerous that most things we deal with on amps running at 500 to 600 V.

You know a X resistance Y wattage resistor can handle the current easily, but don't know how well the diodes will, and you test. Check heat, etc.

Not sure how you thought I was telling you to do something dangerous if you're already sticking things in a tube amp circuit on a regular basis, I already assumed you know how to be safe with electronics.

~Phil

[pompeiisneaks]

Case in point, a youtube channel I watch regularly, he shows failure modes of diodes in this video. He's intentionally over current/voltage etc to see how they fail.




~Phil

[Reeltarded]

I was only joking about the fire fire part. The rest is a test that people do on a regular basis with controlled environments to see the failure mode of things. You obviously expect it to burn up, and need to have precautions set to avoid fire and easily shut down the circuit etc. Yes it is dangerous, but not more dangerous that most things we deal with on amps running at 500 to 600 V.

You know a X resistance Y wattage resistor can handle the current easily, but don't know how well the diodes will, and you test. Check heat, etc.

Not sure how you thought I was telling you to do something dangerous if you're already sticking things in a tube amp circuit on a regular basis, I already assumed you know how to be safe with electronics.

~Phil

roflmao :p