EEVblog Electronics Community Forum
Electronics => PCB/EDA/CAD => Eagle => Topic started by: ashley.hughes on October 01, 2011, 10:52:18 am
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Hi,
I have built up this diagram
(https://files.me.com/ashley.hughes/gt766s)
The ERC Error checker is complaining that
No Supply for implicit POWER pin IC2P V+
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?
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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.
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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?
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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?