Hello, everyone!
BCDs seem simple in theory, but I am having difficulty getting them to work in practice. I'm not sure if I have a bad batch of ICs, or if I've overlooked something, or I am doing something wrong.
I have a K511ID1 Nixie BCDs which I'm breadboarding. I am trying to get a LED to light using the truth table listed in the datasheet but the desired LED won't light. The only LED to light is the output 0, and that isn't by choice. The datasheet says that digit 0 is enabled when all inputs are set to LOW, so I am suspecting that my problem is the inputs.
The setup I have done is supplying 5V and GND to the breadboard power rails using a bench power supply. I hooked up VCC and GND of the IC to the proper rails. I then jumpered the 5V and GND power rails to the A, B, C, D inputs for the digit (LED) I want to enable and the expected LED doesn't light.
My troubleshooting attempts were:
- Verified the voltage
- Verified the wiring
- Verified polarity of the LED to the IC (The LED has a current limiting resistor)
- Swapped ICs (I have five chips).
- Swapped breadboards
- Wrote an Arduino sketch testing the the inputs (a simple blink program)
- Verified that the datasheet I was using (TI's SN74141) was correct by looking at other related datasheets
The chips are NOS with identical date codes. The likelihood of all five ICs being FUBAR out of the box seems slim (unless I did something unintentionally dumb).
I can't figure what else I could overlook, so now I am stuck. Please advise. Thanks!