74hc138 ic simple little circuit


Senior Member
I bought a bunch of these 74hc138 IC's from a auction and searched on the forms (searched probably wrong forums) but couldn't find any schematic of using the 74hc138 with a picaxe
so after reading the 74hc138 schematic and looking around the web I was able to make a small led display just in a row
its not nothing perfect but if anyone had some of these IC's laying around
here is how I got mine to work.

74HC138 SCH.jpgView attachment 74hc138 working code1.bas


Hi Newplumber,

Well done on your 74HC138 project.

Yes, there are only a few past threads discussing the use of the 74HC138.
I guess that the 74HC595 (8-bit serial in to parallel out shift register) has typically been promoted here for simple LED control. The 74HC595 does take more code to drive the LEDs but only needs 3 PICAXE outputs and can be cascaded for multiples of 8 outputs.


Senior Member
Thanks Westaust55
yes and thanks from all your codes/schematics for the 74hc595 I was able to make them work too which is my favorite ic to run leds
so I bought a ton of 74hc595 since you don't have to multiplex if choose not to
Here is a COOL sign I made using seven 74hc595 no multiplexing I made it cool cause even if you don't like it ..its still cool :)


Well-known member
newplumber, that is a "COOL" sign. Perhaps post your construction details somewhere. Others will be interested.


Senior Member
thanks texasclodhopper but my code for it is messy and I cheated by just using i think westaust55's forum for running two 74hc595 so I used almost all the pins on my picaxe 20m2 by
using 3 pins per two 74hc595 ics lol but now I know how to use 8 or more using 3 pins so I will give a schematic and code when I build my "WELCOME" sign.
I would build a "GARAGE SALE" sign but i think people would rip it off .. unless i come up with some tazer anti theft system


Senior Member
Even though it is may -or may not- be messy, you still achieved a nice piece of DIY hardware. And we can all still learn a bit or two from it.
So I would also encourage you to publish the complete details.