Best way of connecting a 2N3055..

Discussion in 'General Electronics Chat' started by JohnnyD, Sep 3, 2006.

  1. JohnnyD

    Thread Starter Well-Known Member

    Aug 29, 2006
    79
    0
    Hi,

    I am making a circuit that uses a 2N3055 where the base and emitter have their own pins but the collector is the chassis of the transistor itself.

    I'm having trouble deciding on how best to connect the collector. I don't really want to solder directly onto the chassis, but what other way is there?
     
  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    A solder tag, a bolt, a nut and lock washers.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    The convention with TO-3 transistors was to get a socket. This took care of insulation problems. It's also possible to get a TO-3 mounting kit that has an insulating washer to go under the transistor body, as well as insulators for the mounting screws. That way, only the case of the transistor is electrically hot.
     
  4. JohnnyD

    Thread Starter Well-Known Member

    Aug 29, 2006
    79
    0
    That's what i've got at the moment. The 2n3055 then a TO3 silicone insulating strip, then the heatsink. The mounting holes are insulated with plastic bushes so the heatsink is electrically dead too. This is the actual product I'm using.

    But it means the mounting screws are electrically dead too so I'd have to use a solder tag on on the topside of the transistor to make a connection with the collector.

    Right? bah, i don't know!
     
  5. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    The bushes go on the bottom side, one for each screw. The screw then is electrically connected to the collector. The solder tag can be placed on either one of the screw, top or bottom side. Unless you want to double insulate the screws and put two bushes each, then you have to have the tag on the topside under the bush.
     
  6. JohnnyD

    Thread Starter Well-Known Member

    Aug 29, 2006
    79
    0
    D'oh yeah! I just measured the continuity and both mounting screws are electrically connected to the collector. Brilliant!

    The only problem now is getting hold of a small number of solder tags. The place i get my components from only sells bags of 100 :(

    Thanks for everyone's help on this, sorry it was a bit trivial!
     
  7. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    You can make a solder lug out of sheet copper. You can make sheet copper by taking a 'real' US penny made prior to 1982 and hammering it flat then cutting it with tin snips then drilling a large hole and a small hole. It helps if you have some solder flux but you can tin it with rosin core solder, tin throughly then bolt on and solder your wire on. You should be able to make a few of these.

    I've even done this without tin snips or drill, just a knife.

    Yes I'm cheap.
     
  8. JohnnyD

    Thread Starter Well-Known Member

    Aug 29, 2006
    79
    0
    lol I'll see what happens. I might just have to use a TIP3055 instead but they take up more room with the size of heatsink i need.
     
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