Need some help identifying old electronic component

Discussion in 'General Electronics Chat' started by Bluebarntrading, Jan 10, 2012.

  1. Bluebarntrading

    Thread Starter New Member

    Jan 10, 2012
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    I was hoping someone could help to identify this electronic component. I found a pile of them abandoned by a military electronics contractor. Some of the other capacitors and resistors there turned out to have some value but I am having trouble figuring out what this set up is. It consists of a Sangamd 1000 MFD Capacitor, a piece with what appear to be cooling fins marked IBM 310890, and another piece that I am not sure what it is and there are no markings. I have posted a couple of pictures. Any help would be appreciated.
     
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  2. jimkeith

    Active Member

    Oct 26, 2011
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    This is a selenium bridge rectifier that is part of a low voltage DC power supply--perhaps 24V @ 1A. It carries an IBM part # because it was manufactured to IBM specifications as was the 1000uf 50V Sangamo capacitor. Part of an old IBM system of some type--perhaps punch card processing unit--Circa 1955.
     
  3. Bluebarntrading

    Thread Starter New Member

    Jan 10, 2012
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    Thank you very much. Never could have gotten there on my own!
     
  4. crutschow

    Expert

    Mar 14, 2008
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    The device with fins looks like an old selenium rectifier. It was one of the first solid-state power rectifiers but had a high junction forward voltage drop of about 1V and each junction had a reverse voltage rating of only 25V (requiring many junctions in series to achieve higher voltage ratings as shown by the numerous plates of the one you have), so they became obsolete as soon as silicon rectifiers became available.

    The third piece appears to be a very cruddy looking transformer.

    Edit: Bluebarntrading beat me to the punch.:)
     
  5. jimkeith

    Active Member

    Oct 26, 2011
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    Those old enough may recall the 50's & 60's TV series "Dragnet" with Jack Webb starring as Sgt. Joe Friday of the LA Police Dept. Well they had an IBM or RCA punch card system that searched for crime suspects--a detailed punch card had been created for all known criminals, so when they were looking for a certain profile (age/physical description/race/crime type etc.) they would do a "run-down" which involved running perhaps 100,000 cards through their IBM computer /sorter that they filmed in process with cards flashing by and being dumped into various stacks. When done, Sgt. Friday and his sidekick Bruce, would always grab a dozen cards or so out of the last bin and go to work--the remainder of the show involved investigating each of the persons indicated--the true crime perpetrator was always one of these and the show often ended with a shootout... Typical scenario.
    Check out this episode--after watching previews:
    http://www.hulu.com/watch/55148/dragnet-frauds-dr-28
     
    Last edited: Jan 10, 2012
  6. Adjuster

    Well-Known Member

    Dec 26, 2010
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    Those selenium contraptions have some significant disadvantages compared to modern devices. They are pretty inefficient, and not very reliable, but the worst thing in my opinion is that they can fail in a way which produces stinking poisonous fumes.
    I would say the smell is something between rotting garlic and sewage.

    Collectors of vintage electronic equipment quite often disconnect such devices, possibly leaving them in place for show while the real work is done by a modern rectifier hidden away somewhere. A series resistor is often required to simulate the extra loss of the old device, to avoid excessive output voltage.

    My advice would be to regard such things as ornaments only. You really don't want that smell getting loose!
     
  7. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    As a former Dragnet fan, I agree with most of your post. However, there really wasn't much gun play in the show. In the episode you linked to for example, the bad guy gave up without any violence whatsoever. By today's standards, the show seems tame and Joe Friday seems like a square (yeah, I know that "square" is an old fashioned word), but in some ways things were better when the good guys were easy to identify. Thanks for the memory jog. :)
     
  8. jimkeith

    Active Member

    Oct 26, 2011
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    How well I remember the odor! Don't remind me...

    Before MOVs came into existence, selenium stacks were also used as transient protectors as they had considerable energy absorption capacity.
     
  9. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I immediately recognized that rectifier. I ran across one last year in an old (50's) machine and couldn't figure out what the heck it was. I thought it was a high wattage resistor but that didn't make sense the way it was in the circuit, and wires terminated to the middle of it. I was getting all sorts of weird resistance readings across it. I had to trace out & draw out the circuit with a question mark and then think "what would make sense there". It was pretty obvious then, and I felt pretty silly.
     
  10. BillB3857

    Senior Member

    Feb 28, 2009
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    If I recall, the smoke that came out of these rectifiers not only smelled bad, but was RED. Correct me if I'm wrong since memory is one of the first things to go. I can't remember what's next.
     
  11. jimkeith

    Active Member

    Oct 26, 2011
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    Yes--not much gun play as they are based upon real cases--Joe didn't have to whip out his .38 snub nose--grossly inaccurate weapon. Today, they would have a swat team with sub-machine guns pointed at the criminal (victim) as they smash him to the floor. My, how things have changed!

    It is hard to believe that a modern handheld has far more power than the entire room of computing equipment shown in the video clip.
     
    Last edited: Jan 10, 2012
  12. Lundwall_Paul

    Member

    Oct 18, 2011
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    This is a rectifier. I saw many of these in 300 volt power supplies while I worked on an old radar in the AF. The radar was dated around 1943
    decommissioned in 1990. I have the Technical orders and can redraw the schematic and see what else I can find on it.
     
  13. Lundwall_Paul

    Member

    Oct 18, 2011
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    selenium rectifiers. I saw some of these in the service in an old radar. Configured as a bridge rectifier in a 36 volt supply.
     
  14. rogs

    Active Member

    Aug 28, 2009
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    I tended to think of that smell more like dead rat!
    Brings back some memories of repairing electronic organs....
    In the early 70's, there were still quite lot of selenium rectifiers, in the early electronic organs that had been fitted into churches during, the 50's and 60's.
    Here in the UK, following WW2, we didn't (couldn't?) import Hammond organs from the US, as we had before th war, and a number of UK manufacturers started up, often using war surplus ex military parts. Including selenium rectifiers.

    That smell would greet you as soon as you went into the empty church, midweek. You knew straight away that either the rectifier had gone, or that a rat had eaten through, a cable loom, and was rotting away deep inside the machine.
    I preferred the rectifier failures, naturally. :)

    Happy days.......
     
  15. Adjuster

    Well-Known Member

    Dec 26, 2010
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    One of the later uses for selenium rectifiers was in voltage triplers used in CRT final anode supplies of TV sets, particularly colour sets made a few decades ago.

    Apparently a visiting repair technician would often make a provisional diagnosis on entering the building, to be greeted by the stench of rotting rectifier.
     
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