OT: Vacuum Tube Projects?

[SWISSNIXIE - Jonathan F.]

Hello Folks,

Being relatively young, i clearly missed the vacuum tube age by a lot of years :-) Still vacuum tubes and especially nixies became my hobby and i'm very interested in them.

The internet is full of audio vacuum tube projects like amplifiers. But i don't want to do audio projects for a buch of different reasons. But i really would like to do a project with vacuum tubes (other than nixies..) that is usesfull to, and shows the beauty of these devices.
The only audio device i would build is a radio, but since AM/FM gets less supported i don't know if its a good idea.

Can anyone here make suggestions what useful* project could be made with vacuum tubes other than an amplifier?

Thanks for your suggestions



* by useful i mean something you could use for a purpose and not just a construction to decorate a shelf.

[J Forbes]

Television sets were a major use of vacuum tubes from the late 1940s till the mid 1970s. They are quite tricky to build, but I've found several old ones to play with, over the years.

Old tube based test equipment is also interesting, I even made a sort of functional clock using an old counter.

https://www.youtube.com/watch?v=VM9TW6GcCQE

I have an tube based Tek scope from the early 60s that I can use to keep my shop warm, since it dissipates about 500 watts just sitting there!

Short wave radio also used tubes, I have a BC-348/Q radio receiver in my office, so I can tune in WWV.

[Dan Harboe Burer]

Useful vacuum tube based instruments could be e.g. a regulated power supply, with various outputs, for tube experiments, an electrometer..a voltmeter.. a Geiger counter with a photomultiplier tube, maybe? :) ..a Theremin.. or what about something as crazy as a stroboscope tachometer? :)

Dan

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[John Rehwinkel]

Useful vacuum tube based instruments could be e.g. a regulated power supply, with various outputs, for tube experiments, an electrometer..a voltmeter.. a Geiger counter with a photomultiplier tube, maybe? :) ..a Theremin..

or what about something as crazy as a stroboscope tachometer? :)

There's a guitar tuner that works like a stroboscope tachometer, built out of vacuum tubes, it's pretty nifty.

I was also going to suggest a theremin (there's a picture out there that's Bob Moog's sketch of the schematic of Clara Rockmore's original theremin, built byy Theremin himself).

I'm currently building an art project that's a vacuum tube visual theremin, that uses a pair of antenna-controlled oscillators to draw Lissajous figures on a CRT.  I'm also playing with notions of using other kinds of oscillators to draw other shapes.

Another one I'm toying with is a hybrid project using a pair of sawtooth oscillators to scan characters in a monoscope and paint them on a CRT (the bits that choose which characters to draw are solid state).

Yeah, I'm fond of CRTs.

There are lots of vacuum tube sound projects out there, like using multiple plate tubes as complex wave generators, growly thyratron oscillators to make distinctive tones, all kinds of effects (sheet beam tubes make great ring modulators, as do

the quadruple diodes available in huge numbers because they were used in color TVs).  Gated beam discriminators were made in large numbers for FM receivers, they make cool sounding distortion.

I'd probably start small, maybe an Eccles-Jordon multivibrator (I've breadboarded one of these in an afternoon), they're fun to play with.  Then you can hook them up in series as counters, with neon bulbs showing the count.

Amazingly, there are vacuum tube breadboards still made by a few companies (Modul-Bus, Lectron, etc.).

- John

[Terry S]

Radio is far from dead....

Here's one of my vacuum tube projects.... Restoration of a Drug Store tube tester. The full story can be read over at rec.antiques.radio+phono

https://www.flickr.com/photos/32165280@N02/sets/72157674341385913/with/9325619978/

It's an emissions-only tester, so only marginally useful, but fun and cool. And if you want to play with tubes you may want a tube tester.

Terry

[threeneurons]

* by useful i mean something you could use for a purpose and not just a construction to decorate a shelf.

You mean functioning ?  I have a tube project, in the queue, that's visual, so its decorative, yet the tubes are functioning as designed. Its a tube color organ.

I've been bothered about the old SCR based color organ circuit that's been floating around since the 60's. It has NO true amplitude-to-phase-angle control. I actually make a TRIAC kit, that does the job properly, and I plan to make a tube version shortly. It will be using both vacuum tubes, and thyratrons.

Here's a timing diagram showing true phase control for TRIACs:

It will utilize single vacuum triode stages as voltage comparators, much like I'm doing here, with a transistor:

And here's an old tube color organ kit, that does NOT have decent phase control, even though the author believes it does, and is probably the bad example that continued over to solid state SCRs:

https://threeneurons.files.wordpress.com/2017/11/radio-news_color-organ.pdf

[HuggerMugger]

A tube-based synthesizer.

 

Some ideas to be picked up here: http://cgs.synth.net/tube/index.html or here: http://www.synthtopia.com/content/2013/01/10/the-knifonium-vacuum-tube-synthesizer/ or here: http://cdm.link/2016/04/this-is-what-a-steampunk-synth-with-25-tubes-sounds-like/

 

Unfortunately, tubes are slightly linear and doesn’t automatically give the nice exponential curve that is esential in making athe octaves.

 

Another cool project would be, still the the musical domain, a Theremin:

 

https://antiqueradio.org/BuildingATubeTheremin.htm

 

http://www.channelroadamps.com/articles/theremin/

 

http://www.theremin.us/126/126revised.html

 

http://www.thereminworld.com/schematics?tag=tube%20theremins

 

Whatever you decide to build, the chances to make a steampunk design increases when using tubes.

 

 

/Magnus K

Sweden

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Virusfritt. www.avast.com

[Dekatron42]

Here's a nice organ to build a copy of: https://www.vintage-radio.net/forum/showthread.php?t=121108 , but maybe nothing for the beginner though....

/Martin

[orange_glow_fan]

 Pick up an old tube based radio (I prefer the wood cabinet versions from the 30's and 40's) Take some time and do a bit of restoration. Then build a one or two tube AM transmitter and transmit your own old ,time radio programming..!

Kerry