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Questions tagged [vacuum-tube]

Any device that incorporates an evacuated chamber in which free-floating electrons are manipulated.

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how do tube filament resistors work on this Type 10?

picture source: "Building a 1929 style TNT Transmitter", The VE7SL Radio Notebook, 2009 https://qsl.net/ve7sl/tnt.html, originally referenced from the 1929 ARRL Handbook I don't know how ...
DeWitt2967's user avatar
2 votes
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186 views

Tube AM transmitter question

I designed an AM tube transmitter based on a crystal oscillator. Can you please tell me if this would work, or what I could improve?
George Chita's user avatar
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Vacuum tube emission (anode current, transconductance) percentage that is considered GOOD

Russian vacuum tube datasheets almost always specifies anode current like Ia = 100 mA +/-20mA at some conditions. The same with transconductance. But western tube datasheets specifies only one ...
Ernestas Gruodis's user avatar
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Fuzzy digits when driving with TPIC6B595

I designed a schematic and PCB of a simple Nixie clock and I hope that someone will be able to explain what's happening. The problem is that when I'm driving the cathodes with TPIC6B595 shift ...
Adam's user avatar
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What is happening to this vacuum tube?

I’m trying to repair a 63 year old record player. Opening it up, all of the electronics have aged badly, except for the drive motor, which is basic enough that it operates properly. I know enough ...
ToastHouse's user avatar
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making a DF96 pentode crystal oscillator

I want to make a crystal oscillator using DF96 vacuum tube. The tube is a small RF/IF amplifier for battery operated systems. This tube is unique in the sense that it only takes 25ma of filament ...
Ashok Das's user avatar
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What is this device? (from historical photo)

Anybody know what this might be? It's from an old photo with my grandfather as a teenager who went on to work on radar during the war and later for "His Masters Voice" repairing televisions. ...
Brad Robinson's user avatar
1 vote
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407 views

Guitar Amp Power Supply Issues

I have a B-52 AT100 guitar amp on my bench (naturally, it wouldn't let me attach the .pdf I have of the schematic, so I had to attach it as two .jpegs. The schematic can easily be found online though, ...
JE61's user avatar
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Vacuum tube voltage regulator - capacitor on the output

I'm thinking about building a tube-based voltage regulator to provide the power for the screen grids of the output tubes. I have seen multiple designs of this and am currently thinking of doing it ...
Pentium100's user avatar
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Magic Eye Tuning Tube Variable Negative Voltage

I am thinking about several applications of magic eye tuning tubes as display pieces and had a question about their operation. I have attached a sample circuit from a datasheet for an EM84 tube. I ...
Efram Goldberg's user avatar
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Solid State Output Tube Driver for a SE guitar amp

I'm learning as I go once again. Consider this output stage segment from a guitar amplifier I physically built: The LND150 is an "depletion mode" MOSFET, whereas the IRF820 is a normal "enhacement ...
Jonathan S. Fisher's user avatar
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Microwave magnetron connections reversable F, FA?

The two connections on a microwave magnetron are labeled F (filament) and FA (filament anode), both being either ends of a heated filament powered by a 3V AC supply, and the FA connection being ...
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How to identify an old oscilloscope tube?

I have this tube: There is no manufacturer or part number written on it, only the numbers 50321. The first 5 I'm not sure. Any idea what can it be and what voltages are needed to operate it? It's ...
vjalle's user avatar
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Reverse Transformer For Smooth High Voltage

So I want to make a valve audio preamp, but need a way to generate clean high voltage DC for the plates of my tubes. I started with rolling my own boost converter which worked well, but was unable to ...
G Frank's user avatar
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2 answers
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Troubleshooting thermionic emission

I am attempting to make an electron beam device work. The setup is very basic - a wehnelt in a vacuum chamber connected to an AC filament heater source and a DC high voltage source as pictured below. ...
Magemathician's user avatar
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MNA matrix of a vacuum tube

I've been working on a project involving a digital model of a vacuum tube. We're currently experimenting with a Wave Digital Filter approach. Now I've been reading Kurt Wegner's fascinating work and I ...
João Vaz's user avatar
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How to find the total gain for a particular gain stage

Can someone help me how to calculate the total voltage gain for this particular gain stage? As you can see, there are five resistors. They are R3, R4, R5, R6 and R7. R4(100k) is the load resistor and ...
SnoopyKid's user avatar
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Powering nixie tube from negative voltage?

I've built a photomultiplier tube supply; it takes +100VDC from a boost converter, which then goes through an inverting (in the sense of postive->negative rather than DC->AC) charge pump to give ...
T.S's user avatar
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Doubt about high voltage measurement from amp chassis to earth ground

I built a tube amp (Fender 5f1 replica) and it works perfectly with a 3 prong power cord plugged into a properly earth grounded outlet. Any voltage on chassis and practically no "hum". I did ...
Cristiano Sarmento's user avatar
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I have a carvin v3m 50watt tube amp head, red plating/bias help

The amp has 4 el84 tubes and 4 12ax7 pre amp tubes, the amp lost about half of its volume and the power tubes are red plating, is there any thing other than the tubes that I should be looking out for ...
Joe Cortez's user avatar
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600V DC Switch method question

I am making a linear PSU capable of O/P 600v @ 300mA. This is for vacuum tube experiments. I need to connect/disconnect the load from the PSU using a switch. I will not turn OFF the PSU itself. I ...
Ashok Das's user avatar
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Designing a hybrid RF ampilifier with tube and transistors

I have an 807 vacuum tube and I want to design a RF power amplifier with it. Since I have only one tube so I want to use transistors for the rest of the power amplifier circuit. The 807 tube will be ...
Ashok Das's user avatar
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153 views

Drive an older VFD tube via an Arduino et. al

I have a beautiful old itron DP95A4 tube that I would like to use as a small display to visualize some data. I suppose I'd need a driver and some sort of multiplexer, preferably used with an Arduino ...
zantafio's user avatar
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How to detect if vacuum tube is overdriven?

I want to somehow indicate(with LED diode for example) to user when vacuum tube is overdriven (When grid voltage is greater or equal than cathode voltage). My first idea was to connect a LED diode ...
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How close can an output transformer be to a preamp tube?

Imagine a layout for a tube amplifier. The power transformer is on one side, and the output transformer, input jack, and preamp tubes are on the other side. (Take a look at the Soldano SLO for example)...
cat pants's user avatar
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Ascertaining Valve Part Numbers

Old valves (vacuum tubes) sometimes do not come in their original boxes. Sometimes the part numbers seem impossible to read. Is there an easy way to read an apparently illegible part number? Would UV ...
Autistic's user avatar
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-1 votes
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Little Bear T11 tube phono pre-amp VACUUM TUBE upgrading

I have a Little Bear T11 vacuum tube phonograph pre-amp. It has three Shuguang 6N2-J "Military Grade" vacuum tubes which I want to upgrade. The pre-amp also has a Chinese made 6z4-J Rectifier. The amp ...
Scott D. Ruby's user avatar