That's about the opposite of what you want to do. Applying 8.75 V to a dead cold filament will cause a lot of current to run in the filament, thus, causing a thermal chock. That's not nice...
I wonder if it has to do with the fact that you have two control loops in your circuit. One that controls the voltage across the filament, the other controls the current. I would eliminate the voltage control loop and just program the current to 1.4 A. You could make it adjustable so that you can adjust for 5.0 V across a hot filament.
~Tom
I wonder if it has to do with the fact that you have two control loops in your circuit. One that controls the voltage across the filament, the other controls the current. I would eliminate the voltage control loop and just program the current to 1.4 A. You could make it adjustable so that you can adjust for 5.0 V across a hot filament.
~Tom
The schematic says a maximum of 7 volts input and you get 8.75 out? Perhaps you are overloading it?
It looks very strange. You should have slowly increased voltage between + and - signs for filament connection, as drawn.
Why not taking a dead simple regulator/pass transistor ? The PSU in the pic is over engineered in many ways. There are so many parts, I could build another amplifier from that 😀
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