As of May 31, 2023, we have updated our Code of Conduct.

Questions tagged [vacuum-tube]

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

23 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
5 votes
1 answer

Amplify Raspberry Pi Zero's audio with '60s tube amplifier circuit

I have been restoring some old '50s and '60s tube amplified radios, fitting them with Bluetooth while maintaining the original electronics and functionalities. I achieved this by connecting the ...
Sander Voss's user avatar
2 votes
0 answers

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
2 votes
0 answers

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
2 votes
0 answers

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
  • 135
2 votes
0 answers

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
1 vote
0 answers

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
  • 23
1 vote
0 answers

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
  • 6,520
1 vote
0 answers

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
1 vote
0 answers

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
0 votes
0 answers

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
0 votes
0 answers

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
  • 215
0 votes
0 answers

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
0 votes
1 answer

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
  • 109
0 votes
0 answers

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
0 votes
0 answers

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
0 votes
0 answers

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
0 votes
0 answers

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
0 votes
0 answers

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
  • 101
0 votes
0 answers

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 ...
J K's user avatar
  • 167
0 votes
0 answers

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
  • 423
0 votes
1 answer

Calculating voltage, current, and impedance values on an old transformer

I'm working on an old valve amplifier, with the intention of reusing the transformers in a new project. I've used what I know of transformers to calculate the ratio of each winding the corresponding ...
Josh Taylor's user avatar
0 votes
0 answers

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
  • 13.8k
-1 votes
1 answer

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