Transistor switching issue

[Murugesh_89]

Hi,
I am detecting a wave with ON time of 2.4ms and OFF time of 0.1ms with amplitude 4V. I want to switch this with equivalent 5V. So i connected a 2.2k at the base and 22K at the collector with the other terminal to 5V and the output taken from collector of transistor 2N3904.

In the normal ON state i am getting 0V at the collector with reference to ground. but in the off time i did not get complete 5V state instead i get around 2.5v. some time not even switching. i think the lower 100us duration causes this problem.

So what is the exact problem and how should i overcome this...

Thanks,
Murugesh

 

[chuckey]

It looks like the transistor is leaky. What you are saying that with no volts on the base, the collector current is 2.5/22 mA ~ .1 mA. Try returning the base to earth via a 10 K and reducing the 22K to 4K7.
Frank