My brain or my chip which is defective?

D

desperate one

New Member

• Feb 23, 2011

• #1

i am a newbie with a question regarding a 74ls14 Hex Schmitt Trigger Inverter. i have connected 5volts to pin 14 and hooked pin 7 to ground. what do i have to do to pin 1 to get a high 5volt signal out of pin 2 for that matter same scenario pin 2 high to low? i think i have tried everything. is my chip possibly fried or is my brain. thanks for any help

 

MikeMl

Well-Known Member

Most Helpful Member

• Feb 23, 2011

• #2

If you have applied both a high and low to pin 1 with no change at pin 2, then your chip is defective. What is the voltage at pin 2 while you alternatively connect pin 1 to pin 7 or pin 14?

 

ronv

Well-Known Member

Most Helpful Member

• Feb 23, 2011

• #3

If you ground pin 1 pin 2 should be high. If you put +5 on pin 1 pin 2 should be low. If you leave pin 1 open who knows.

 

J

Jaguarjoe

Member

• Feb 23, 2011

• #4

Logically all that this chip does is invert so that when the input is low, the output is high and vice-versa. Did you accidentally put more than 5v on pin 14? Is the chip backwards? Can you try another chip?

 

D

desperate one

New Member

• Feb 23, 2011

• #5

Thanks for the help at least its not my brain (this time)

thanks for the help that sounds right to me

 

K

KeepItSimpleStupid

Well-Known Member

Most Helpful Member

• Feb 23, 2011

• #6

TTL inputs usually float high.

 

B

BrownOut

Banned

• Feb 24, 2011

• #7

I agree your chip is probably bad. But just for a sanity check, connect all unsued inputs to ground and repeat your experiment.

 

Mr RB

Well-Known Member

• Feb 26, 2011

• #8

Yep it's probably latched up. Ground all inputs apart from the one you are driving.