74HC08N doesnt latch ?

Thread Starter

Kandy Boy

Joined Jun 24, 2021
1
I am using the 74HC08N chip. Why doesn't the first AND gate latch itself ?

I have connected the output of the first AND gate to its own input.

I have used two resistors, the one on top is a pull-up and the one in the bottom is the pull-down

After I release the button, the diode should take care by feeding the current from the output back into the input, why this doesn't happen, the LED is not always turned on after I press the button once.

fce4b145-6b52-47ed-b9e7-bcb56ca6d222.jpg
 
Last edited by a moderator:

ericgibbs

Joined Jan 29, 2010
13,634
hi KB,
A circuit diagram would make the circuit easier to follow, also I assume 5V Vcc.?
E

Update. [Corrected my 1st image]
Drawn the circuit, check for accuracy,
Note: a 74HC08 is an AND Gate.

Hint: What is the operating voltage of a RED LED,? , so what will pin #3 pull up too.?
E
ESP_ 516 Jun. 24 08.56.png
 

Attachments

Last edited:

MrChips

Joined Oct 2, 2009
24,198
It is generally not a good idea to drive an LED and use the output of the gate for a logic signal both at the same time.
Use another section of the 74HC08 to drive the LED (using a 330-1kΩ series resistor).
 
Top