Polarity Errors in Vallidate ERC

[mbrandonisio]

Hello,

I'm running in to an issue drawing a schematic from https://www.circuitstoday.com/simple-10w-audio-amplifier for a 10Watt amp. I drew the schematic paying careful attention pins 2 and 3 being in different order from the F360 component compared to the schematic I was copying from for the LF351 Op Amp.

I get 4 errors that I'm not sure how to address. Looking at the original schematic all looks in order. Even Looking at the data sheet for the LF351 I have the schematic correct yet I get a Polarity error saying I have Pins 4 and 7 on wrong Vcc and Vee.

Additionally, I've added power jack that is my understanding that the T is for tip and should be positive while R is the external barrel. I also get a polarity error.

Any thoughts what I've don wrong? I'm new to electronic and wanted to learn schematic drawing.

See attached items for details.

[mbrandonisio]

These are the errors in the screenshots.

• Warnings (4)
A POWER pin IC1 V- connected to N$7
A POWER pin IC1 V+ connected to N$4
A POWER pin CONN1 RING connected to - 12V

A POWER pin CONN1 PIN connected to +12V

[jorge_garcia · Accepted solution]

Hi @mbrandonisio ,

I hope you're doing well. What makes you think these are polarity errors?

These ERC warnings are just the electronics environment letting you know that the POWER pin is connected to a net, instead of a supply pin which is what is normally expected. Your schematic is correct and you can ignore these warnings.

PS. The schematic on that website doesn't look correct to me. I could be wrong, but I wouldnt expect this circuit to perform very well. For one, the output stage is outside of the op amp's feedback loop so the non-linearities of the transistors are not compensated for. More concerning still is the fact that the transistors are not being fed any output signal from the op amp. It reminds me of a current-dumping amplifier but the architecture is not correct. I haven't built it so I could be totally off here but it gives me a bad feeling. Just thought I should mention it.

Let me know if there's anything else I can do for you.

Best Regards,

[mbrandonisio]

Hello,

Ah, yes. It is a warning. I'm still learning what is important and what is not.

So you are saying that best practice is to place a power pins to connect power to the net? I'll try this. My aim is to create clean schematics since a warning is still telling me I did something out of line.

I do appreciate your comments on the circuit. I was using it as a sample to practice creating schematics with and routing traces on the board. Making the boards it are a lot like a puzzle trying to route without collisions or via's.

I'll try adding power pins to the net then power to the power pins. Thanks.

[mbrandonisio]

Hello,

I added supply symbols and labeled them Vcc and Vee. Then connected the jack to the Vcc and Vee net.

I get same warning with supply symbols. I'll ignore them and move on to another schematic for practice.

Thanks again,

[mbrandonisio]

Oh, Wait. I just figured out what you went.

I renamed the Vcc and Vee to PIN and RING and then renamed the N$7 and N$4 to V+ and V- and now no warnings.

I get it now, at least the naming.

I want to look more in to your comments on the circuit.