Quick transistor question.

goodpickles

New Member

• Sep 23, 2004

• #1

When I hook up a 2n3905 transistor to the output off 555 timer it does not operate...Do I need a FET? Does the 555 issolate the power supply?

 

williB

New Member

• Sep 23, 2004

• #2

the 3905 is a pnp so i hope you are expecting something to happen when the 555 output is low..

https://www.fairchildsemi.com/ds/2N/2N3905.pdf

 

goodpickles

New Member

• Sep 23, 2004

• #3

yes I am. I tryed a fcouple thing and I did get it working. I removed a pullup resistor

 

Exo

Active Member

• Sep 24, 2004

• #4

Can you post a circuit so we can see the entire setup?

 

V

VISHOK

New Member

• Sep 25, 2004

• #5

what is the Frequency and the amplitude of the 555 output.

 

Oznog

Active Member

• Sep 25, 2004

• #6

Did you put a resistor on the base to the transisor? Otherwise it's almost shorting the TTL output of the 555, which could have adverse effects on the 555's operation.

 

goodpickles

New Member

• Sep 27, 2004

• #7

no I did not put in a resistor. As I said is does work, but doing this may extend the 555's life