Please Help, Problem with Project.


Joined Apr 16, 2011
Each of those integrated circuits requires 0 volts on pin 7 and +5 volts on pin 14

Neither the schematic nor the breadboard picture show power to pins 7 and 14

Decoupling capacitors would be nice too - but one thing at a time

100 Ohm resistor is too low for standard LED. Change to 330 Ohms

Thread Starter


Joined Mar 10, 2022
hi levy,
Welcome to AAC,
You have to tell us what is the problem with project.?
it doesn't light the Led when I turn on the switches I don't know cause I've connect every thing correctly , maybe I have a problem analyzing schematic diagram can u help me, please


Joined Apr 16, 2011
Look at the small line above column 30. This might suggest that the top two power lines are broken half way along.
Same for lower two power lines.

Move the power supply and the LED to the left half of the breadboard, or provide four short links to connect left power lines to right.


Joined Aug 1, 2013
Each of the three ICs has unused gates. All of the inputs to all of the unused gates must be connected to either Vcc or GND. They do not all have to be the same, but they must be tied to something.

All of the outputs of the unused gates must be left unconnected to anything.