The basis for this tube preamplifier started out as a post in the Super simple single stage tube preamp thread on the website Forum. One of the members (see Mark’s 4S Universal Valve Preamps) had suggested building a Super Simple Single Stage Preamp (“4S” Preamp for short) and there was much discussion concerning various tubes, gain, noise, etc. and several designs were presented using various dual triode tubes. Then the proverbial gauntlet was thrown down with the phrase “switch from 12AU7 to 12AX7″. My answer was to design a universal line stage preamplifier that would work well with an entire range of tubes. Thus was the 4S Universal tube preamplifier born.
4S Universal Preamplifier for 12A*7 Tubes - [Link]
I’ve recently become interested in Nixie tubes. Nixie tubes are neon filled glass tubes that contain cathodes in various shapes, numbers being the most common, and a mesh anode. Passing a current through the cathode causes the neon gas to ionize which makes it light up.
The problem with these tubes is that they voltages of around 170V in order to ionize the gas. Fortunately, most tubes only need a few mA which makes the supply design simpler and easy to run off a wall wart.
A low cost Nixie Tube Power Supply - [Link]
In this mini tutorial we introduce a quick and cheap way to make your own Nixie Tube sockets to use them on your next Nixie project. A socket enables you to change a damaged Nixie Tube quickly and with minimum effort.
- plastic stand-off bases that comes with many of the Nixies
- universal IC socket header
- glue (optional)
- common tools
Haris Andrianakis writes:
This is a project i designed a year ago but never built, because of not enough spare time. This month i found some free time so i started building it and i send the pcb layout for manufacturing.
All started when i received some IV-11 vfd tubes from an ebay seller i ordered from and i started testing and prototyping by first trying to simple light up the VFD tube.
A VFD tube works like a 7-segment led display with some small differences.
A) The Filaments. The Filaments exists to power the tube. We have to supply these two pins with 1.2Volt and nothing more (polarity doesn’t matter).
B) The Grid. The Grid is like the common anode of a 7-Segment LED display. So the Grid has to be pushed high at 60Volt (in these tubes) in order the segments to be able to light up.
C) The Segments. The Segments light’s up simple by pushing them high at 60Volt.
IV-11 VFD Tube Clock Final Design - [Link]
Ante Vukorepa draws our attention to this video of Claude Paillard, a French radio amateur (F2FO), making his own tubes (also known as thermionic valves) from scratch. “The video depicts the whole process, from winding the filament through making the glassware, assembly and vacuuming, to testing. Pretty awesome!”
For more information on Claude’s activities as well as links to articles on vintage radio topics, go to Claude’s website. (In French; if English is needed, click on the Google translate link at the top of Claude’s webpage.)
Homebrew electronic tubes - [Link]
This is a PDF in English published in 1947 and features 45 complete schemes of tube amps, including diagram drawing material list and description of operation. Ideal for anyone interested in old amplifiers (Vintage) and the supporters as well as a modern valve amplifier. The power of the circuits presented in the book ranges from 1 to 75 Watts.
Practical Amplifier Diagrams – Tubes Audio Power Amplifiers - [Link]
The excellent book on transmitters that offer contains 467 pages of information in English about transmitters. Radio Transmitters was published in 1961 by engineers at the laboratory of ITT radio transmission.
Here’s a whole book dedicated to transmitters! Targeted at professional engineers rather than hams, this covers it all from oscillators through power amps, modulators, power supplies, and antenna matching.
Radio Transmitters – Tube power RF Circuits - [Link]
This is a project for a Russian IN-13 bargraph Nixie tube to use it as an indoor room thermometer. It is named “NixieTherm” and is also available as a fully complete kit incl. enclosure as shown at www.Nixiekits.eu
The IN-13 is a special construct of a gas discharge Neon display and works similar to the well know Neon bulb in illuminated mains power switches or as Nixie tubes. But this bargraph has a current depending length of the glow. As all other cold discharge tubes also the IN-13 needs a “little bit more” high voltage to work; at least 120VDC. The current through the tube must be limited, normally with a resistor. In the NixieTherm this is done with a high voltage transistor, as we need a variable current from 0….4.5mA.
Analog IN-13 bargraph Nixie tube thermometer - [Link]
Matt Renaud writes:
It’s time for a little confession: I don’t always spend as much time on my power supply designs as I should. Sometimes I get excited about my latest circuit and after looking for just the right tubes, output transformers, coupling caps, and low noise resistors, the power supply design becomes almost an after thought. Sometimes things turn out ok and there are no problems. Other times I end up with bad voltages, unacceptable power supply sag, channel crosstalk, or worst of all, a hum that I just can’t seem to eliminate. It’s at these times that I always wish I had taken a little more time to get it right.
The truth is, there is no reason to suffer power supply set backs like this. The design of basic tube power supplies is actually very straight forward. And, if we rely on the excellent work of those who’ve come before us (O. H. Schade, N. H. Roberts, D. L Waidelich, H. J. Reich), we don’t even need to tackle any advanced math or taxing mental gyrations to arrive at some truly excellent power supply designs.
Power Supply Design for Vacuum Tube Amplifiers - [Link]
Bruce Heran writes:
This is a project that I always wanted to do, but managed to put off for a long time. It has been over a year in the doing. Partly because there are so many good phono preamps in existence and I was slightly concerned that it was beyond my design skills. It took over a year to get it up to my satisfaction. There were several iterations and lots of frustration along the way. My goal was to make a preamp that would not embarrass the builder with inferior performance. I used a number of commercial products for comparison. My thought was why bother to design and build something that was already available for a lower cost. As it turns out, it was not as inexpensive nor un-complicated as I first hoped.
The Groovewatt Tube (Valve) RIAA Phono Preamp Project - [Link]