Electronics > Eagle

ERC Errors complaining



I have built up this diagram

The ERC Error checker is complaining that

--- Quote ---No Supply for implicit POWER pin IC2P V+
--- End quote ---

Now I get why as the op-amp needs a V+ and V- but where are these pins? or how do I connect to them when I can't see them? The part is a LM324N which is in the default libraries

Any ideas?

Those pins are invisible and thus global. Place two power symbols in the schematic named V+ and V-. Then connect V+ to +12V power and V- to ground.

Thanks I changed the V12+ to V+ and 0V to V- and it keep it all happy thanks for that.

As for the rest of the circuit does it look alright as far as conventions and stuff go?

You left the on-inverting inputs of 3 op-amps floating. This will cause unnecessary power consumption. Put 2 10K (or any value) resistors in series to make +6V and connect all the unused non-inverting inputs to there. You don't connect them to ground because that saturates the transistors inside the op-amp, increasing the power consumption. Leave the inverting inputs as they are right now to make a voltage follower. You can also find a use for them (buffers can be useful and sometimes, adding a separate op-amp just to amplify a signal that was supposed to be amplified on the previous or following stage can correct oscillation problems. Personally, I like to use them as comparators, along with some LED's to indicate some status regardless of it's relevance  ::)).

Is that a VU meter?


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