Hello,
ok, this is my situation:
here are the players
U1: 4 to 16 Line Decoder/DeMux SN74HC154
U2: An 8-Input NAND gate SN74HC30
an LED
a switch
now, this is what I'm trying to do. I would like,
State 1: open switch
I don't care what the Decoder is doing, LED is on and NAND spits out a 0
State 2: closed switch
when my Decoder spits out a 1 my LED should turn off and my NAND gate spits out a 1
State 3: closed switch
when my Decoder spits out a 0 (low) my LED should light up and my NAND gate should spit out a 1 (high)
I've sketched this out, in the sketch I replace the NAND gate with an inverter for simplicity. My question is, I faith that the way I've sketched it State 1 is good, State 2 makes me feel funny... but I think it would work, state 3... might not be so great because I'd be relying on the voltage drop across the LED to pull down my NAND gate's input (inverter in the sketch)
can anyone comment on my thoughts, or tell me if there's a better way to wire this to accomplish the three states I'm trying to get.
![untitled.JPG untitled.JPG](https://www.electro-tech-online.com/data/attachments/32/32131-b6a29efb7586f800d81b049e185ac490.jpg)
much thanks!
(sorry about the dark pic)
ok, this is my situation:
here are the players
U1: 4 to 16 Line Decoder/DeMux SN74HC154
U2: An 8-Input NAND gate SN74HC30
an LED
a switch
now, this is what I'm trying to do. I would like,
State 1: open switch
I don't care what the Decoder is doing, LED is on and NAND spits out a 0
State 2: closed switch
when my Decoder spits out a 1 my LED should turn off and my NAND gate spits out a 1
State 3: closed switch
when my Decoder spits out a 0 (low) my LED should light up and my NAND gate should spit out a 1 (high)
I've sketched this out, in the sketch I replace the NAND gate with an inverter for simplicity. My question is, I faith that the way I've sketched it State 1 is good, State 2 makes me feel funny... but I think it would work, state 3... might not be so great because I'd be relying on the voltage drop across the LED to pull down my NAND gate's input (inverter in the sketch)
can anyone comment on my thoughts, or tell me if there's a better way to wire this to accomplish the three states I'm trying to get.
![untitled.JPG untitled.JPG](https://www.electro-tech-online.com/data/attachments/32/32131-b6a29efb7586f800d81b049e185ac490.jpg)
much thanks!
(sorry about the dark pic)
Last edited: