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Stabistor diode STB523 - anybody got a datasheet?
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david77:
I've been looking online all day to find some info on a stabistor diode STB523. Had no luck so far.
Has anybody got any info on this part? It's used in a HP power supply.
HP part no. 1901-0460

free_electron:
If memory serves me well that's a diode stack: a bunch of diodes in forward mode ( not a zener ! ) 15 volts made by General Electric.  looooong gone ...

the difference with a zener is that it does not conduct in reverse.
 a zener in reverse acts like a diode : 0.7 volts drop . stabistors don't do this. i homebrew these using a simple 1n4007 and a 14.3 volts zener. works fine


--- Code: ---  Z14.3v     1n4001
---|<|---------|>|---
    \


--- End code ---
Fixing a 6236A ?  ;D

david77:

--- Quote from: free_electron on June 24, 2012, 11:22:33 pm ---Fixing a 6236A ?  ;D

--- End quote ---

Not exactly. I am thinking about building one from scratch.

So you just put the 14,3V Zener and the 1N4007 in series, anode to anode? Which side represents the anode and kathode of the original STB then?
No, hang on I think I can answer that myself: Kathode is kathode side of 1N4007, anode is anode of 1N4007, too. Right?
The dash in the second line is not important, I take it?

Thanks for your help, much appreciated.
Shuggsy:
Sorry to dig this up from the grave, but I think this just became relevant to me as I am indeed fixing an HP 6236B!

I'm hoping you can help me understand the STB523 diode a little more free_electron (or anyone else feeling the need to comment... ;)). If I have things straight, it's merely a stack of diodes that has a threshold of 15V before it begins conducting when forward biased? This opposed to the 0.7V like a 1n4007 or similar?

I pulled one of these out of my supply because the current limiting behavior started at a lower output current that it should have on my supply and one of this is in the circuit. Testing it on my bench, it started conducting around 1.8V when forward biased... so if it's supposed to have a threshold/forward voltage around 15V then this one is definitely headed to the trash bin and I'll be taking free_electron's advice on how to home brew one! 8)

Any help is appreciated!
poorchava:
I think this is simply 21 diodes in series. For a current to pass through these, the voltage has to exceed the sum of forward voltage drops. Stabistors are supposed to be better for low voltage references. One example of such device is BAS17 (google for datasheet). I think that hacking up 21 1n4148's in series won't necessarily do the trick, because stabistor is optimized to have the voltage drop varying very slightly when current changes.


EDIT:
googled that one up:
http://www.circuitsonline.net/forum/view/76899
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