Mysterious components

Thread Starter

foshi81

Joined Jun 18, 2020
4
Hello,

I am new to this forum, so forgive me if I placed this thread under wrong category.
I came accross some mistery electronic components that I can't find any info about.
They look as some kind of phototransistors, when measured with multimeter they act as photoresistors.
There is no text marking of any kind on devices. Only color marks. Company from box label probably doesn't exist anymore.
I wouldn't waste my time to find info about these parts if they weren't packed like this. As you can see on the attached photos, every element is in its own case, and almost 200 elements packed in big high quality case.
So if anyone has seen something like this or knows the logo or industry that could find this interesting please let me know.
The last resort is that this ends up in scrap for gold salvage, but it looks too nice to end up that way :)
 

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AlbertHall

Joined Jun 4, 2014
10,026
The ones with a window in the top (and three legs) are almost certainly photo-transistors.
Are the ones that don't have obvious windows completely cased in metal? If so then they are clearly not opto devices.
 

Thread Starter

foshi81

Joined Jun 18, 2020
4
I forgot to mention these without window in post...yes, I agree they are not opto devices. But they came in same box so I took a picture of them too.
I didn't take any measurment of these without window, but these with window are strange. Some don't have any resistance, neither forward voltage (like they are burned out), and some have variable resistance between only two legs, depending on the amount of light coming in.
This is why I wrote they look like photo transistors but act like resistors.
Maybe I am measuring something wrong, but I have some skills in checking regular transistors :)
 

AlbertHall

Joined Jun 4, 2014
10,026
If they are transistors, photo or otherwise, you should be able to measure the two 'diode' junctions.
If you measure between emiitter and colector, with the correct polarity, then they should show a resistance which varies with light.
 

MrChips

Joined Oct 2, 2009
21,329
They are probably the same phototransistor, one with the window and one without.
They are used as a pair in a differential circuit to compensate for temperature changes.

1592489043939.png
 

Thread Starter

foshi81

Joined Jun 18, 2020
4
I have done some measuring and arranging these devices.
First, I haven't found two of them with same color code (some samples in attached photo, divided in rows by first color).
Second, they are definetly not transistors, not a single one of over 70 samples had a two diode juctions as AlbertHall mentioned.
I haven't found any resistance from pin 1 to other pins. Resistance is found on half of devices between pins 2 and 3 in range from 100Kohm to 25Mohm. Usualy resistance is for example 300k in one direction, 400k in reverse. Very strange.
Where I found large impedance (>5M), it is in one direction, in reverse I get some pulses but not a constant value (I use digital multimieter UNI-T UT71D). On other half of samples, no resistance at all (or my multimeter couldn't find it)
All resistance measurmens were taken in dark and in light conditions. I even tried measuring capacity, but nothing found.
As for the MrChips comment, I made a temperature test and yes, the one without window change resistance. 300k device heated to ~100C goes down to 100k.
To be more interesting, I have found 3 of them (without window) in this bunch of samples that act as a diode between pins 2 and 3 only.
So the mystery continues, and even gets more interesting :)
 

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