Problems using 4000 ic

Thread Starter

Twiggy12345

Joined Oct 24, 2014
2
I am trying to make a circuit that is using a ldr with a 9v battery to power 3 4000 ic. A 4001, 4081, and a 4071. The outputs are connected up to transistors. Everything works fine for two of the outputs, but, the last ic is putting out a flashing Led rather than a solid signal.
I tried swapping the ic over like musical ic, but the new ic I put into the original spot has flashing and the ic I pulled out of that spot is now fine, a solid light.

Are the 4000 series gates supposed to flash or do I not have enough amps going in or something?
 

Papabravo

Joined Feb 24, 2006
21,157
A 4000 series chip can do either. It can flash or output a solid signal. In order to do what you want it to do it absolutely must be wired correctly. Post a schematic and any pictures you might have.
 

Papabravo

Joined Feb 24, 2006
21,157
You asked in a private conversation about how to make the chips do various functions. I prefer that questions be asked and answered in the open forum. I'll explain how I would use a 4001, which is a quad 2-input NOR gate to do the three functions.

Using DeMorgan's law we can think of this gate as performing 2 identical functions described this way:

1. A high .OR. a high is a low
2. A low .AND. a low is a high​

Let us say that when the output is high the LED will be on and when the output is low the LED will be off.

To make the LED be on, we need both inputs to be low all the time.
To make the LED be off, we need either input to be high all the time
To make the LED flash, we need one input to be low, and the other input to be alternately high, then low, then high again and so on.​

Have you got it now? Can you work out the details for the remaining parts?
 
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