Monday, August 12, 2019

DF97 electron tube as battery powered microphone preamplifier


At your risk. Take all safety precautions. Any voltage or current can be dangerous. A fuse should always be used in series with a battery for fire hazard protection.


Here is the datasheet:
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf


The direct filament cathode power consumption is only 25mA at 1.4V, biiingoooo!!!


It is vari μ which can be a very good thing as it is remote cutoff by definition.


Past experience with the electron tube was bit impressive but it had been tried with only 12V at anode and Pleiades bias. It should work great with say 24V and Pleiades bias or just a higher anode potential and more conventional bias.


A pocket size battery powered electron tube microphone moister amplifier of very low power consumption should be possible. Just one AA battery could supply filament cathode. 2 for example garage remote control 12V batteries could supply anode. An output transformer could be directly connected to anode.


A possible schematic can be the Pleiades V6 with a few adaptations for direct filament and a little higher anode potential.


There is no reason why ultra low noise perforce should not be achieved with such an electron tube and a good capacitor coupled to grid microphone input transformer.















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