Electronics > Projects, Designs, and Technical Stuff
Can a diode amplify sound?
ELS122:
Well if an cathode is positively positively charged than it stops emoting electrons, and if it’s negative it emits electrons. I guess it would probably only weaken the signal but theoretically I think it is possible to drive an audio signal in the cathode as an grid.
Berni:
The problem with your amplifier is that any current pulled down from the output also flows back into the input. Since a diode is a 2 terminal device there is nowhere else that it can go.
Your grid and cathode are basically the same terminal in your diode (heater is not a terminal because the cathode is solid and not a grid). What gives the triode tube its amplification abilities is that the grid and emitter are two separate terminals. When current flows trough a triode it mostly flows between the cathode and plate, very little current makes it to the grid where the input is connected. Its the cathode that is intruding the extra current into the circuit in order to provide more current into the output and amplify power. If your cathode and grid are the same terminal then all the current must come from the input and hence all the power comes from there.
ejeffrey:
--- Quote from: ELS122 on December 12, 2019, 05:21:19 am ---Well if an cathode is positively positively charged than it stops emoting electrons, and if it’s negative it emits electrons. I guess it would probably only weaken the signal but theoretically I think it is possible to drive an audio signal in the cathode as an grid.
--- End quote ---
Positively charged relative to what? This sounds like confusion about "absolute" voltage which doesn't mean anything. All that matters is the voltage difference between the cathode and anode. The cathode is always emitting electrons. If the anode is more positive than the cathode it will attract those thermally emitted electrons, if not it won't. i.e., it will rectify the signal. However, it won't add any extra energy. If you try to bias the anode as you do in a triode, it will then just capture all of the cathode current regardless of small variations in the cathode voltage.
strawberry:
does he mean diode as triode with direct heated cathode and cathode plate as a grid?
Ysjoelfir:
--- Quote from: strawberry on December 12, 2019, 08:57:04 am ---does he mean diode as triode with direct heated cathode and cathode plate as a grid?
--- End quote ---
could be, but that would be a pretty awfull triode i assume, since... well... how should the cathode tube that encapsules the heater regulate the flow of electrons, if those pesky little beasts don't even get out of the cathode tube?
despite the cathode material emitting the most electrons being on the outside of the cathode tube...
so we would have a "grid" that is emitting electrons. "grid" current would definitely flow - which won't be a huge problem since the cathode used as the grid will be much tougher than a thin grid, but that thing wouldn't be controllable in a normal way at all.
And we would have a grid made of solid sheet metal. no electrons from the "cathode" (=heater) could pass to the anode, besides from the few that go outside the cathode tube where the heater enters.
but those wouldn't be very regulated from the potential of the cathode at all I assume, but a little bit of influencing coule be possible.
But - I am intrigued now and would love to try this idea at home. maybe this weekend...
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