evostars wrote:I understand the opamp that makes the 5.333 V &12 V needs 2v headroom. So 14V should be enough. Actually the tr303 had 12 V feeding the opamp i believe. Correct me if I'm wrong....
So with the modded bridge rectifier, the opamp gets powered like the TR303. That's another plus. Anybody like warble?
It's not the opamp that makes the 5.333v. the 5.333v is put onto the input of the left opamp. the left opamp is set to follow the input voltage. IC22 is responcible for the 5.333v. IC22 is an adjustible zener-diode with a 0.5v range. the resistors and potmeter on the right is the circuit responcible to tune to the 5.333v.
With the 12V you are correct, that one is generated by the op-amp, due to the way the output of the right op-amp is fed back to it's input via the resistors on the right of the right op-amp (still follow me? )
To be able to get to the 12V output, the op-amp needs to be fed with a voltage that is at least 14V, due to the power that is lost in the op-amp circuitry (an op-amp is made out of many transistors as you might know) I got the 2V power drop from the specs of the op-amp.