I have a 555 timer outputting a pulsed signal with an amplitude of 4.6V. I am then inputting the signal into a transistor to pulse the LED but when I do this the amplitude drops to .8V. How do I keep the maximum amplitude??

 

Schematic?

 

I have a 555 timer outputting a pulsed signal with an amplitude of 4.6V. I am then inputting the signal into a transistor to pulse the LED but when I do this the amplitude drops to .8V. How do I keep the maximum amplitude??

Sounds like you are putting the signal directly into a BJT without a series resistor, which is a no-no.
The base-emitter junction of a BJT looks like a forward biased diode so it requires a resistor in series with base to limit the base current to the desired value (typically about 1/10th of the maximum collector current for it to act as a switch).

 

I agree with crutschow in that you are probably trying to drive a transistor base without a means of absorbing the rest of the voltage -- but whether this is done via a base resistor or an emitter resistor or some other means depends on the circuit. How do you expect people to tell you what is wrong with a circuit when you don't provide the circuit?

 

Did somebody tell you to do that, or did you just figure you'd try it out to see what happens? Inquiring minds want to know.