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Replace LM2931 by Using 78L05


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I'm building a project where I get the PCB + panel to buy my own parts. It needs a clock buffered by cd40106 and runs a cd4017. The sequential output of CD4017 produces a programmable voltage sequence that enters the output stage based on lm358. The complete sketch can be seen here. I just realized that I didn't supply power to lm2931, which constitutes the + 5V line of digital integrated circuits. I looked at the data sheet and it looked like it was just a low voltage drop 5V regulator with a rated current of 100 mA. Should a good 78L05 voltage regulator be a good substitute for driving only 4xxx logic? I'm almost sure I'll be okay, but I think I'll say hello. Below is the relevant part of the sketch:


Likewise, I want to use TL072 instead of LM358, because I have many such devices.

I tried to contact the PCB manufacturer and he gave me an extra past task, but I didn't get the answer, so I think I can handle everything faster by simply asking here and making some modifications alone.

PS: LM358 stage is only a typical 100K/100K mixer for CD4017 production. Then it supports 100K/100K by 15PF and 330R by output jack.

Thank you in advantage~

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  • 9 months later...

I would be careful in making a substitution of the LM358.  Although it is a very old part, it has some desirable performance characteristics that make it superior, especially at voltages near ground in a single supply application.  
Be careful of the product selector guide at Digikey when it comes to operational amplifiers.  The supply voltage numbers in the selector guide do not always line up with the data sheet.


If you post the whole circuit with the  op-amp, I might try and simulate it for you.  A complete schematic please.

Edited by Clyde
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