Issue with a hex inverter (sn74ls04n)

[gjkrenik]

Hi guys I am currently taking a digital systems class and have run into some issues with operating a hex inverter, sn74ls04n. I have read the datasheet and this is what I have come up with: Pin 7 is connected to the ground, pin 14 is connected to a +5V power source, pin 1 is connected to a 0 to 5v square wave function. When I check the square wave on an oscilloscope it appears as it should oscillating in a square wave like fashion from 0 to 5V.

My issue is when I check the output of pin 2 on the oscilloscope I expect the square wave to look the same but inverted but instead it looks like a square wave that oscillates from like 4V to 5V.

I have tried a few different 74ls04n chips but no luck. Is there something I'm doing wrong? Thanks for the help!

 

[MikeMl]

Are yours in the J or the W package?

 

[PCBWING]

It sounds like the ground problem. You can compare your circuit to the datasheet.

 

[Mikebits]

Looks like only the 54 series came in the W package but I see what you were thinking. Maybe he has a real small value pullup resistor on the output, or two outputs are shorted? Hard to say without a schematic.

 

[audioguru]

The output of a TTL 74LSxxxx IC has a low of 0.1V to 0.4V and a high of 2.7V to 3.5V.

 

[tkbits]

At what frequency?

 

[audioguru]

The frequency does not affect the output swing of a logic IC much until its slew rate can no nonger produce a square-wave.

 

[Roff]

Do you have the negative terminal of the 5V supply, the ground on the signal source, and the scope ground all connected together?