about BJT

Discussion in 'General Electronics Chat' started by CantataAndAria, Nov 24, 2014.

  1. CantataAndAria

    Thread Starter New Member

    Nov 14, 2014
    What is the maximum voltage Vcc (on Collector side) applied on BC547 BJT? in our lecture notes it's usually 12V, but when I try this value it just burns.
  2. Papabravo


    Feb 24, 2006
    What does the datasheet say?
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
    Welcome Cantata you are now a full member of the select electronics community since you have passed the initiation ceremony - burning a transistor.


    The BC 547 should be guaranteed to 45 volts at the collector.

    However you need to include a resistor in the circuit to limit the current and stop the transistor frying.
    Last edited: Nov 25, 2014
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Integrated circuits can be connected directly to power supplies but transistors MUST have a resistor or some other load to limit the current passing through it. Loads can be light bulbs, motors, heaters, ...

  5. BobTPH

    Active Member

    Jun 5, 2013
    It is not the 12V on the collector that caused the problem, it is the current that flowed though the transistor. With the base grounded, the transistor would easily withstand 12V because no current would flow.

  6. WBahn


    Mar 31, 2012
    Can you sketch a circuit diagram of how you were using the transistor when you smoked it? There are a few ways of destroying a transistor. Perhaps the three most common are asking it to dissipate more power than it can handle, asking it to withstand more voltage than it can handle (even if little or no current is flowing), or asking it to withstand more current than it can handle (even if little or no voltage appears across it). By far the most common is the first and that is almost certainly what you have done, but it is hard to tell unless we know more about how you were using it.
    KJ6EAD and absf like this.