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78xx series are vulnerable to input voltage above 35V.
Excellent AG, you have spotted the obvious shortcoming- it is only an outline design and I couldn't be bothered to sort the startingI do not see how the zener diode-opamp-transistor power supply in post #81 starts. When power is applied then the (+) input and output are at 0V so they might stay like that. I know that the LM358 uses PNP input transistors that try to pull the inputs positive a little but both inputs will go positive a little. But the (+) input has a higher resistor value but again if the input offset voltage is the wrong polarity then it will not work.
Sorry I am WAY to busy to go around deleting your nonsense , say pretty please LOLWould admin please delete
Your circuit look pretty like basic of what inside a LM431 and the circuit in my friendy's guitar preamp use 8V2 zenner and LM741 opamp.
Yes, like my think, I have many EI small transformers, usually dual 5-18V, very well.Nikolai,
It would be much better if you could power the preamp from a separate winding on the main PSU transformer or, better still, from a separate small transformer.
Yes, like my think, I have many EI small transformers, usually dual 5-18V, very well.
It is amazing the number of times you see servicing aspects completely ignored, or worse still made impossible for no good reason. I don't know about American cars (autos) anymore but European cars are now especially bad, leading to unnecessarily high servicing costs. On the first Ford Escorts you could change the gearbox in an hour with no hassle. Just try that on the modern equivalent, the Ford Focus. Mind you, the Austin/Morris Mini was always a pig to work on.And connectorize your I/O for easy board removal.
No, I mean fan for power amp sections.Rolls Royce preamp
Although it will do no harm, it will not be necessary to shield any wires except those carrying high voltage AC.
No, a fan would not be necessary for the low power dissipated in a pre amp.
As a general point, always design and build equipment with development/servicing/maintenance in mind so that no item is inaccessible. There is an unwritten law that says that, the more inaccessible an item is, the more likely it is to give trouble. For example, with the case design that I proposed for the power amp in the Transistor Equivalent thread, you will notice that all items are accessible, including the underside of the power amp PCBs.
spec
No, I mean fan for power amp sections.
My construct right?
Mate you so need to move!! Life without a fully stocked parts bin is just existing and not living, build a raft