who knows this transistor?

[sethiyadav]

I have a scr dc drive ,after testing i found a transistor is open,but there are no number on it ,sir, how to find it .[I m too weak in english,plz ignore]

 

[Mooly]

Looks like you have tried to copy the circuit from the components.
I'm guessing here... something like a 2n5551 NPN although the pinouts are different

Your ground connection that goes through the tranny to the Emmiter as I labeled it... that would mean an NPN device...
If the circuit wasn't quite right as drawn then a PNP device would have the Collector connected to that point... which then leaves two legs... enny meeny miny mo
Official definition here
Eeny, meeny, miny, moe - Wikipedia, the free encyclopedia

Sorry can't be more specific but without seeing for real it "could" be a PNP or an NPN. You are just going to have to try it and see. That tranny connection driven to ground is the starting point NPN... emmiter goes there as drawn, and PNP and the Collector goes there.

 

[sethiyadav]

you are right sir,this is npn,i have another one in same circuit,but the manufacturer scratched on it to remove the number ,e c b are same as u have shown.

 

[megajocke]

It is probably a PUT (thyristor with anode-referenced negative-triggering gate). Something like this:
http://www.onsemi.com/pub_link/Collateral/2N6027-D.PDF

It won't measure the same as a BJT.

 

[Mooly]

Those two transistors actually form a "discrete" unijunction like this,

 

[megajocke]

That is not what is shown in the schematic. Considering the placement of the capacitor, a PUT seems the most likely alternative.

 

[sethiyadav]

thank you sir megajocke,2n6027 is working properly.thanks again for youir guidance.