Ever seen this???

[Bernardduur]

Hey all! I was scavanging this old beaten up, empty Dynacord head (I think) and I found this unit:

Pic 1
Pic 2

The person I got it from said it was a germanium diode; I measured it through and it is a diode

Will check in a D+ like circuit

[Sir H C]

Looks more like a Selenium diode.  Those were much poorer semiconductors so they needed to be bigger to lower the resistance.

[Bernardduur]

Thanks!

Can it be used in such a device? Will it sound?

[jrc4558]

Yes, it is a selenium rectifier. It will sound.

[Paul Perry (Frostwave)]

Selenium diode drop is about 2V.
Another one to look out for, is the copper oxide rectifier. (hint: if you have a broken analog AC voltmeter from the 50s... look inside).

[marlin]

It looks a bit like this:



Is it a selen rectifier also?

[Ronsonic]

Yep. More selenium.

Don't be surprised if you find them dead. They always leaked more than silicon and most have failed by now. For a pedal application it isn't that big a deal, but there's lots of old tube gear that used these in the bias supplies. Those should just be replaced on GPs.

Ron

[zachomega]

As everybody is kind of hinting, the selenium rectifiers were junk...even when they were brand new.  Nothing worth keeping onto in my opinion.  I have some brand new ones in boxes that I'm half tempted to chuck in a box of other more useful crap just to get rid of them.

-Zach Omega

[marlin]

So it sounds, but it sounds like crap? 

[Paul Perry (Frostwave)]

I never met a diode I didn't like...... come on, give it a go!! I bet it's going to have a really soft knee.
Back in the 60s I had some from a drone target plane avionics system power supply that consisted of stacks of disks (the individual disks are only good for about 60v from memory, maybe less). I disassembled them & cleaned them (they were potted with bitumen for weatherproofing). I can still remember the smell of the selenium.... didn't realise quite how poisonous it is, but I'm still here

[marlin]

So it's poisonous, sounds like crap and so big it'll hardly fit in a D box 

I have to try it....

[gez]

I love the smell of burning Selenium in the morning...smells like....well, burning Selenium.

[Ronsonic]

So it's poisonous, sounds like crap and so big it'll hardly fit in a D box 

I have to try it....

That's the spirit. Be sorta interesting to see a couple stacks sticking out of a pedal with Borg-wires going to the terminals. They might actually sound good in a pedal. And it's an application where their failure won't do serious harm.

Ron

[Bernardduur]

The sound is kinda weird; I never got a diode in that cut all the treble in the sound.

I measured the diodes; as germanium gives around 200 (??) and silicium around 800 (??) this one gave 400 (??)

the sound was muffled and fuzzy; louder then germanium diodes, more fuzzy then silicium diodes. And, as stated above, it cut treble.