What’s the deal with V.Bias

A

ac30irons

Active member
So looking at this schematic I am confused with the whole V.Bias thing. I am likely wrong, but I would normally see ground where they are on this schematic. Do they just all link together through pin 6 and 7 of IC1 ?

It’s got me all twisted as it’s not what a schematic would normally look like, including the power section.
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Yes, they all link together. Some designers throw their signals to ground and others to Vref (or V Bias in this case). There is a voltage divider cutting the voltage in half along with a filtering cap before going into opamp buffer configuration.
 
BuddytheReow said:
Yes, they all link together. Some designers throw their signals to ground and others to Vref (or V Bias in this case). There is a voltage divider cutting the voltage in half along with a filtering cap before going into opamp buffer configuration.
Click to expand...
Thanks dude - I was really confused as to why there like be a mix of that, and a few grounds kicking about. Iv knocked up a PCB layout for it. I would normally flood both sides for ground, but I have done one side ground and the other V.Bias. Every day really is a learning day.
 
Op-amps typically want to see a bipolar power supply - something like +/-9v (with reference to ground). Just using a 9v battery you only have a unipolar supply (+9v/0, or -9v/0 if you flip the battery), so by using a equal resistive divider you get +9/+4.5/0.

If instead of the ground/zero reference you connected that to 4.5v, the op-amp would see a quasi-bipolar supply - of course you then need to use capacitors to block the DC reference from other parts of the circuit that are referenced to ground.
 
I see a lot of unnecessary AC coupling in circuits. You can save components and board space by continuously referencing to virtual rather than true gnd. The kicker is ensuring that there is nowhere for DC to go to create DC drops. Pots only generate thump when there is DC DIFFERENCE ACROSS them. So if your opamp output is at 4.5v and there is no DC path to GND, then the following stage will remain at 4.5 as well.
 
Well - mine officially blow - I would love to say I have been educated but it’s all PHD to my primitive brain - thanks so much all !!!
 
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