We were doing a school project, attempting to create binary data storage. In the process of putting the circuit together, we discovered that moving closer or farther from the circuit affects the brightness of the LED. When we disconnected the button from the nor integrated circuit, the circuit got extremely hot and burnt out. We also recreated this same circuit on another separate bread board, and the same exact thing happened. If anyone has any idea what is happening, please let us know!

 

I don't see a schematic. Without that, it is impossible to see what you intended for the circuit to do. Also, the photo does not show all circuit connections.

There is no current limiting resistor in series with the LED. This can cause the chip to burn up even with no other circuit errors.

All of the unused inputs to the device are unconnected. This can cause the chip to fail even with no other circuit errors.

One of the inputs to the one gate you are using is unconnected. This probably is the cause of the strange behavior, but without a schematic it is impossible to say.

There is no power supply decoupling near the chip. This can cause the circuit not to operate properly even with no other circuit errors.

Again - without a schematic, all answers are just semi-random guessing.

ak

 

I don't see a schematic. Without that, it is impossible to see what you intended for the circuit to do.

ak

we will add one! thanks

 

I don't see a schematic. Without that, it is impossible to see what you intended for the circuit to do. Also, the photo does not show all circuit connections.

There is no current limiting resistor in series with the LED. This can cause the chip to burn up even with no other circuit errors.

All of the unused inputs to the device are unconnected. This can cause the chip to fail even with no other circuit errors.

One of the inputs to the one gate you are using is unconnected. This probably is the cause of the strange behavior, but without a schematic it is impossible to say.

There is no power supply decoupling near the chip. This can cause the circuit not to operate properly even with no other circuit errors.

Again - without a schematic, all answers are just semi-random guessing.

ak

Do you know of any easy ways to create a schematic?
Or why an effect like this could be created without using any sensors?

 

You can draw a tidy annotated schematic with pen and paper then upload a clear sharp photo of it (file size <300k preferably).
What AK says about unconnected inputs is of particular importance with CMOS circuits, such as the 74HC02 (which is what your IC seems to be if I'm reading its markings correctly). Be aware too that CMOS chips can be damged by static electricity so require appropriate handling. Your body is both a good antenna (which caused the effect you noticed) and a good source of static!

 

I don't see a schematic. Without that, it is impossible to see what you intended for the circuit to do. Also, the photo does not show all circuit connections.

There is no current limiting resistor in series with the LED. This can cause the chip to burn up even with no other circuit errors.

All of the unused inputs to the device are unconnected. This can cause the chip to fail even with no other circuit errors.

One of the inputs to the one gate you are using is unconnected. This probably is the cause of the strange behavior, but without a schematic it is impossible to say.

There is no power supply decoupling near the chip. This can cause the circuit not to operate properly even with no other circuit errors.

Again - without a schematic, all answers are just semi-random guessing.

ak

 

That's good. Now address the points AK made in post #2.

 

Speaking of being technically pedantic - Vcc should be labeled Vdd.

General rules for all IC circuit design, analog, digital, whatever:

1. ALL inputs must be addressed: tied to something directly, tied through a resistor, determined to have internal resistors or circuits so no external parts are needed - whatever. Your circuit has nine problems, and this is eight of them.

2. Read the datasheet for each component.

In this case, read the datasheet for the LED. If it does not state explicitly that the device has current limiting built-in, you need to add it externally.
Read the datasheet for the IC to learn its max safe output current.
Read the datasheet for the LED to learn its forward voltage drop.
Use Ohm's Law to calculate what is needed to protect the chip.

If this was covered in class, review the material. If it was not, your instructor can contact me here.

ak