Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

[SOLVED] Transistor doesn't reach CUTOFF region.

Status
Not open for further replies.
M

Mo_Sh

Newbie level 2
Joined
Aug 19, 2013
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
15
Hi,

I am doing a simple circuit, a PN2222A transistor is switched on by a 5v and a 11v on the collector.
The problem is that when I ground the base I don't get 11 volts on Vout instead I get 7.5 volts.
Why this is happening?!
The circuit is as follows (I am connecting the base to the ground as this is the case that has the problem)
9812841200_1376898797.jpg
 

It should be 11V because the transistor shouldn't be conducting. Either the transistor is bad, you have it wired incorrectly or your voltmeter is drawing a lot of current!
7.5V is a likely value you might see if two of the transistor pins are crossed over, it is the kind of voltage you expect from a PN junction in it's breakdown region.

Brian.
 
  • Like
Reactions: Mo_Sh

    M

    Mo_Sh

    Points: 2
    Helpful Answer Positive Rating
I guess you have connected it incorrectly. 7.5V would be a typical reverse Vbe breakdown. Check your connections

Keith.
 
  • Like
Reactions: Mo_Sh

    M

    Mo_Sh

    Points: 2
    Helpful Answer Positive Rating
May be source direction changed ?? or change in transistor connection....
 
  • Like
Reactions: Mo_Sh

    M

    Mo_Sh

    Points: 2
    Helpful Answer Positive Rating
Yup it's inverted, I inverted the transistor and it works okay now, however this connection is the opposite to what is mentioned by the datasheet .... weird.
Thanks all.
 

Be careful - some pictures of transistors show the view from the bottom, some the view from the top.

Keith
 
  • Like
Reactions: Mo_Sh

    M

    Mo_Sh

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top