6P1 "NuTube"

Somewone here (me, actually) once conjectured about using a VF display as a gain element.

Terrible as a tube, especially for $50. Probably a good 60 Hz magnetic field sensor.

Sort of a small, poor-quality thyratron. Not too practical, but a fun way to kill an afternoon in my retirement (circa 2040 hopefully).

Yeah, those plate curves would give small children nightmares, if they knew what they were looking at.

And they're schlooow.

Cheers

Phil Hobbs

When I turn 100 ;-)

Typical for triodes.

...Jim Thompson

Naturally

Yep, it's been done. You can build a ring modulator with 'em too

I'm guessing $50 is the "middleman makes his cut" price, not if one were to order direct from the factory in quantity, fortunately.

They're probably designed to be used in the "classic" "tube-harmonic-exciter" circuit for beatboxes and stuff: run the same signal 180 degrees out of phase into two tube grids (grid resistor strapped between the sections), take output from plats into a differential amplifier, sum into another diff amp with the original signal so you only get the difference between what went into the toobs and what came out, mix into original signal with a variable "Warm" control

The plate curves would be very linear in the region between 40 and 80 volts Va and 1.0 -> -1.0 volts on the grid. Sadly the anode can barely handle any power dissipation.

This is for the tube-sound audio people?

Pretty much the only reason you'd bring any kind of new vacuum tube product to market these days I suppose...;-)

I'm thinking about microphonics, especially from that long suspended filament.

it works well enough

mad price, mad specs, obsolote tech.

NT

VFDs are lousy for that. Hopefully they've at least added more than the usual display supports.

What I don't understand is why 1.7mW anode dissipation? I suppose it keeps heater current low for battery use. If it were meatier it could work as a headphone amp too.

But really you don't need to pay 50 notes for a dual triode. Unless you want very low heater power.

NT

Tube warm machine idea:

Adjust the grid resistor for best warm.

(the pot on the last opamp should be on the input resistor not the feedback resistor)

Also connections on diffamps should be swapped to work "right" I believe...:-)

you only need to connect the filament just ignore the rest

for added reliability just shine an amber led though the bottom ;)

I have to check the feedback connections again; it should be sum the out of phase signals to get 2x with commmon mode noise from the tubes rejected, then take the difference of that with an appropriate scaled "dry" signal to leave a "distortion residue" signal, then sum that in some proportion with the dry signal.

With the right component values it will certainly be...audible, though I don't know if it would be pleasing

"There I Fixed It"

What's the gain of a triode that has a current sink in the cathode?

What's the polarity of the gain?

The toob is not drawn right; it's a direct-heat filament. And that circuit will need a floating filament supply.

Here it's just shorthand for "some kind of cathode bias network for DC the particulars don't matter"

use a resistor bypassed with a capacitor. Or an LED

Since the filament doesn't draw much current I think you could feed a voltage regulator from the B+ for the direct heat filament voltage, and bootstrap the "ADJ" pin from the cathode follower's output.

"There I Fixed It"