Need help about my traffic light project

Thread Starter


Joined May 26, 2012
Im doing a two way traffic light project, i have build the circuit in multisim and its run perfectly like one way red and the another way green and so on, but when i build the circuit in breadboard the two red led are keeping 'ON'. I had tried figure out by dismantle the circuit and rebuild again many time, changing the IC, testing the IC part by part but the problem still the same, anyone can help me? The project based are using 555timer, CD4017BE counter, and 74HC4072( 4 input OR gate), 74LS32 ( 2 input OR gate). The schematic are in the attach file.



Joined Nov 23, 2012
A CD4072 (0-18 v supply allowed) used in your simulation is not EXACTLY the same as the 74HC4072 that you are using in your circuit (absolute max supply voltage 7 volts).

Your chips has likely been damaged by your 9V battery.

Read Datasheets.