Dim LED's on and off

Hello, I’m new to the forum. I haven’t touched electronics for almost 10 years. I took about 1 years worth of electronics classes in high school.

I am currently working on a custom built computer case. I would like to have the bottom of the case lit up by some LED’s but I would like for the LED’s to “pulsate.” So I would like to build a circuit that is powered by one of the standard computer power supply 4 pin molex connectors. I want the circuit to dim some LED’s on and off. I have found plenty of “how to’s” to get the LED’s to flash but what I want, is to have the LED’s slowly increase in brightness and then slowly decrease in brightness, and to continue to do this in a loop.

Any kind of help would be greatly appreciated.

Thank you

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Thanks for the reply. I was wondering what the second un-marked amplifier is, is it just another 1458? The drawing shows a power supply of 9v, I think a computer power supply 4pin molex is 12v, will this hurt the circuit?

Thanks

Yes, they're both the 1458 which is a dual op-amp IC, you could just as easily use the LM358.

The circuit should also work with 12V.