Playing with Electrons

It could be a nice book title.


It is nice playing with electrons while making microphone, guitar, record player cartridge preamplifiers. Or other top quality headphone amplifiers, or power amplifiers. Or radio telescope or radio front end amplifiers. Or tape recorder or magnetic tape saturation simulating amplifiers.
Or oscillators, electrons moving back and forth.


Now it can be done much more easily without the bulk, danger, complexity, hum, noise and weight and expense of a high tension power supply.


If a high Megohm resistor is connected from anode to grid the electron tube is still negatively biased but less so and can operate with a battery of less than 12V.


The heaters can be supplied with the same battery.


Very low secondary emission effects ensure unheard off low noise.


And the sound quality is amazing as the circuits you can make are operating in class A meaning electrons are flowing all the time.


A very suitable tube is the EF183 high transcondutanc variable amplification factor electron tube.


In the Pleiades circuits the tube is usually triode connected, meaning the anode connected to all grids except the control grid. The cathode is normally connected to minus battery or ground.


The signal from your mic or guitar or whatever is coupled to the control grid through a coupling capacitor.


The output signal can again be taken through a capacitor out of the anode.


A load resistor is connected to the anode as usual, between anode and battery plus so that the amplified current can be converted to output voltage.


It is important that a fuse is connected in series with the battery for safety.


References:


Operating features of the Audion - Edwin Armstrong


Pleiadss amplifier schematics - euroelectron blogspot


On preserving the transconuctance of an electron tube at an anode potential as low as 3.6 volts