My IC chip isn’t working properly

[AnauNaga]

I have a 4070B I.C. Chip, along with a breadboard, that is a quad 2-input chip and It was working fine when I first got it. Ground was hooked up to it and all the inputs affected the output. Now what is happening is only the right side of it works and the left side inputs all go directly to ground for some reason. I put a resistor on ground that was about 21k ohms and that was when it was somewhat functional which wasnt needed when I first used it. Is there something that I may have been doing wrong?

Also, I’ve used the chip for a while, using it multiple times in adders and pulling it in and out of the breadboard, which was a softer pull so I didn’t ruin it if I could.

 

[AnauNaga]

I should also mention that I’m running off a 5v power supply

 

[WHONOES]

You may have damaged it with a static discharge from you body removing and replacing it in your breadboard.

 

[kellys_eye]

It also costs (about) 50c - it can't be fixed but it can be replaced......

 

[(*steve*)]

Also remember that all cmos inputs net to be connected to a valid logic level. You can't leave them floating (disconnected).

 

[AnauNaga]

Thanks. I thought about static so I hooked up a budget anti static mat By getting aluminum foil and hooking a wire from it to my ground on my breadboard.
I also realized that some inputs need to be connected to ground or powered.

If the chip I’m working with has a ground pin hooked up, could I keep a pin floating, such as a quad 2-input xor gate?

 

[davenn]

could I keep a pin floating, such as a quad 2-input xor gate?

NO, all unused input gates must be tied to either 0V rail or +V rail. Doesn't matter what the digital chip eg ... CD4000 series, 7400 series
I prefer to do that via a 1k resistor to +V or direct to ground ....

 

[hevans1944]

Doesn't matter what the digital chip eg ... CD4000 series, 7400 series

The 7400 series TTL ICs are a little more tolerant of open-circuited pins, which generally will float to a logic-high level for inputs. However, that's not guaranteed and poor design practice to depend on it happening. I too prefer to pull unused TTL inputs to the +5 V Vcc rail through a 1 kΩ resistor, or connect them directly to ground.

CMOS (CD4000 series) MUST have their unused inputs pulled high or low, NEVER left open-circuited. It is easy to forget to do this when bread-boarding, so double check before applying power.

 

[WHONOES]

The 7400 series TTL ICs are a little more tolerant of open-circuited pins, which generally will float to a logic-high level for inputs. However, that's not guaranteed and poor design practice to depend on it happening. I too prefer to pull unused TTL inputs to the +5 V Vcc rail through a 1 kΩ resistor, or connect them directly to ground.

CMOS (CD4000 series) MUST have their unused inputs pulled high or low, NEVER left open-circuited. It is easy to forget to do this when bread-boarding, so double check before applying power.

Totally agree.

 

[AnauNaga]

Thanks, that really helped