2N3773, fake or not

Discussion in 'General Electronics Chat' started by R!f@@, Jan 23, 2016.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    I bought these. Number is coming off.
    I read one member pointed out how to test these.
    Like to know how.
    I got 1 PSU, 0 - 60 V 6A, CV and CC.
    and another one 0-20V with no CC.
    Tell me how to blow these transistors.
    PS. I already opened a dispute.
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The 2N3773 should be capable of more voltage and power as the 2N3055:
    2N3055 NPN TO3 60 Volts, 15 Amps, Hfe 20min, 115 Watt
    2N3773 NPN TO3 140 Volts, 16 Amps, Hfe 5-60, 150 Watt

    Did you already blew one?

    Bertus
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Bear in mind that the Wattage ratings are for specific conditions (pulse duration, heatsinking) as per the datasheet.
     
  4. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    I dumped 3 Amps into BE junction of one, CE open and so far it is testing OK.
     
  5. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Here is the datasheet from ON.
    There is given a max base current of 4 A.

    Bertus
     
  6. Lestraveled

    Well-Known Member

    May 19, 2014
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    Hfe can vary over a wide range so gain is not a good test.

    I would measure break down voltage. Put a 100K - 150K resistor in series with the collector. Base connected to the emitter. Measure collector-emitter voltage while increasing the voltage to >150 volts.
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    Your power supply can only provide enough current to damage BE junction.

    You have to test all of the parameters if you want to determine if they are counterfeit.
     
  8. ISB123

    Well-Known Member

    May 21, 2014
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    Why don't you just open the case and look at the die.
     
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  9. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    I guess I will open the one that I wiped the number off with paint thinner.

    @Lestraveled
    I cannot provide any voltage above 60V
     
  10. Lestraveled

    Well-Known Member

    May 19, 2014
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    What will you do after you open it?? Do you a "good" transistor to compare it to??

    Send me one and I will put it on my curve tracer. I can not load it at more than about .2 amps but I can supply over 200 volts.......oops it does not look like you are in the US.
     
  11. recklessrog

    Member

    May 23, 2013
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    Be very careful if you start sawing the thing open, if they are "New old stock" they may contain Beryllium (Beryllium Copper) This material is EXTREMELY hazardous and can cause death if inhaled. At the very least wear a good face mask and latex gloves and do it in a location where the dust cannot escape and get into the air. Also beware of Vacuuming the dust up as you may expose yourself to it when you empty the container.
    When I worked at one establishment, people working with this material were made to wear hazard suits and were de-contaminated before they could leave the work area.

    Maybe someone will correct me on this as it was 40 years ago that i was working at that establishment, but i believe that Beryllium Oxide is used as an insulating material in some power transistors, especially power R.F types, and it is the Oxide that is lethal in even very small quantities. (Only a few micro grams)
     
    Last edited: Jan 23, 2016
  12. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    I was afraid of that. The chemical part.
    Don't think I am willing to take the risk for a mere 10 bucks.

    I will load it to 6A @ 60V and dump 3A into base and see what happens.
     
  13. recklessrog

    Member

    May 23, 2013
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    That's good sense, Please take care.
     
  14. absf

    Senior Member

    Dec 29, 2010
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    10 bucks for how many pieces? Are they from eBay China?

    You can get them from Element 14 for about 2.50 to 3.00 USD per piece.

    My friend gave me 10 pieces 10 years ago for making 12V DC - 230V AC inverter. But we never use them to their max rating.

    Allen
     
  15. Lestraveled

    Well-Known Member

    May 19, 2014
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    At these parameters (6A @ 60V) they could be 2n3055s and you could not tell the difference.
    The distinguishing parameter is the collector voltage. Test that.
     
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  16. Lestraveled

    Well-Known Member

    May 19, 2014
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    You a steely eyed, no BS, man of electronics. You can figure out how to make 150Vdc with the parts you have on hand in 5 minutes. You only need a few milli-amps. (If you wait too long you will have ten people telling you ten different ways how to do it.)
     
  17. R!f@@

    Thread Starter AAC Fanatic!

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  18. R!f@@

    Thread Starter AAC Fanatic!

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    @Lestraveled
    OK....I have a Variac, a 220V to 110V 100W step down (isolated) transformer.
    I can get 150VDC I believe.
    So, show me the works
     
  19. Lestraveled

    Well-Known Member

    May 19, 2014
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    @R!f@@
    OK, Perfect!

    This is a basic circuit to measure Collector Emitter break down voltage.

    [​IMG]
    The part values are not critical. The cap value can be any value over say 1 uF that will handle the voltage.

    Look at the transistor as a zener diode in this circuit. At some voltage it will start to conduct. Measure the current by looking at the voltage across R1. As the voltage increases, you should see almost no voltage across R1 until you get close to the breakdown voltage. Then the voltage across R1 (EC current) will increase very rapidly. Find the point where the current just starts to rise and then measure the voltage across the transistor. This will be the Collector Emitter breakdown voltage. If it is a good 2N3773 then that voltage will be about 140 volts.

    Oh yea, Be careful
     
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  20. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    If the insulation on the secondary of your step-down transformer can handle 120V, flip it and feed about 55 vac from variac to the secondary of your step down transformer. The primary (connected as secondary in this case) will output about 110VAC. With about 300VAC peak to peak. That is about 150 DC after rectification and filtering caps are added. Adjust variac as needed to dial-in exactly 150VDC. Make sure you have some small (1k to 10k resistors on the filter caps to ground to allow draining caps if you need to turn down the voltage, otherwise, the caps will lock in the higher voltage with the rectifier diodes.

    Cheers.
     
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