Wednesday, August 1, 2018

The fewest components electron tube pre amplifier?


1 9V battery in series with a fuse holder for safety


2 a 13CW4 Nuvistor electron tube


Perhaps this must be it.


It is derived from the Pleiades V6 amplifier with further component reduction.


Pleiades V6 schematic



The pull up bias resistor may not be needed as the anode supply is 9V and there would possibly be anode current when the grid is floating (at its negative value) or at space potential. The same battery would supply the heaters and would underheat them thereby making the grid not so negative.


A coupling capacitor would not be needed if the previous stage has a series capacitor and no terminating resistor.


An output transformer would not be normally needed if the following stage in the signal path has a terminating resistor which will play the part of anode resistor.


If needed to have the load impedance in the pre amp itself then impedance coupling can be used. For example an inductor at the anode circuit. A coupling capacitor may not be needed if the following stage has an input capacitor and no input terminating resistor.


Acknowledgement to Panos for bringing awareness to least component count.





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