Author Topic: Kicad 5.0 is not recognizing a global power net  (Read 182 times)

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Offline hummusdude

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Kicad 5.0 is not recognizing a global power net
« on: April 13, 2021, 04:13:55 am »
I have an audio pre-amp with active tone controls and digital volume control via a dPot. The power to the board is +- 25VDC from a power supply board for a power amp...I plan to put the pre-amp board in the case with the power amp. VDC in goes to an L7815/L7915 pair of linear voltage regulators for the op amps in the analog side. But to power the digital components I used an L7805 that was supplied from the output of the L7815. I know I could drive it right from the +25 VDC line but I thought it might dissipate less power if I used +15VDC.

But in tweaking the circuit I decided to use a small wall wart to power the digital components. I've read different things about potential problems with noise so I wasn't convinced that it would be a problem. It solved the problem of the 7805 getting warm and I couldn't see much noise on the power rails.

I decided to go back to the L7805 out of prudence. I do have form fitting heat sink for the L7805 so probably I can use it and the heat won't be too much. But when I put it back in the schematic KiCad now thinks that the output of the  L7805 and the L7815 are connected and they are both at +15VDC! The global nets on the outputs of each are clearly not the same...or am I missing something?
 

Offline twospoons

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Re: Kicad 5.0 is not recognizing a global power net
« Reply #1 on: April 13, 2021, 04:21:16 am »
or am I missing something?

Yeah - the green line through U7 thats connecting 15V to 5V.  Looks like Kicad is doing precisely what you asked it to do.
 

Offline hummusdude

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Re: Kicad 5.0 is not recognizing a global power net
« Reply #2 on: April 13, 2021, 04:53:24 am »
Doh!
 


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