Using 2N3055 and transformer to switch 220volt

[jacquesl]

And if it’s possible to use a transformer like example if I don’t have that 250v smart transistors I only have 2N3055 and MJ2955 capable to switch high current 15A max @ 60v
So in the specs it say 115w but 15A x 60V = 900wat
So how does that work?

Will be possible to use a 2N3055 or 2 to switch 220volt using a transformer to convert your high current to high voltage like say 220volt and a transformer

[cliffforrest]

You had better explain EXACTLY what you are trying to do:

eg is this AC or DC??

If AC you are not even in the ball-park as BJTs are not suitable at all!

What do you want to do?

[-=terran=-]

The specs work like this: At any time, the voltage and current must not exceed either of their maximum limits (I < 15A and Vce < 60V). However, the total power dissipated must also be below the max (So, Vce * I < 115 W, roughly).

As a general rule, it's not normal to use multiple transistors in some configuration to achieve a higher Vce rating. You can certainly do it though (see your thread in Solid State). I'm not sure exactly what you are looking to do here, more detail is needed. Like cliffforrest said, if you want to use a transformer, AC is required. If you are looking to merely switch voltage to some device on and off (not very quickly), a relay may be better considering the voltage. Otherwise, what you are asking is a form of switching supply - if this is the case, see the Power Supply forum for more details. This produces nothing like household AC though. I hope this helps, or maybe it confuses more

[jacquesl]

Ok, the purpose is to use a step-down transformer as an isolator and the Low voltage, High current transistors all combined to do all the work or a high voltage transistor