Born well into the transistor era of the late 80s, [Fernando] missed out on all the fun you can have with high voltage and vacuum tubes. He wanted to experience this very cool tech, but since you won’t find a tube checker down at the five and dime anymore, where exactly do you get a vacuum tube to play around with? [Fernando]’s solution was to rip apart the vacuum fluorescent display from an old radio (Google Translate) and use that as a triode.
Inside every VFD is a filament, grid, and cathode – three simple elements also found in the triodes of just about every tube amp ever made. By applying a small voltage to the filament, a larger voltage to the cathode, and sending an audio signal to the grid, this triode amplifies the electrical signal coming from a stereo or guitar.
[Fernando] built his circuit on a breadboard, and with a little tweaking managed to get a fairly respectable amount of gain from parts salvaged from a radio. While using VFDs as amplifiers is nothing new – we’ve seen it a few times before, tube builds are always great to see, and bodged up electronics even more so.
[Claude Paillard] is truly talented. He makes triodes by hand. This is a long and arduous process that has many steps, each of which could be messed up pretty easily. [Claude] makes it look easy though.
You might recognize this from way back in 2009 when we covered it on hackaday.com
[thanks for the tip David]
We’ve seen homemade x-ray devices and we’ve seen people making vacuum tubes at home. We’ve never seen anyone make their own x-ray tube, though, and it’s doubtful we’ll ever see the skill and craftsmanship that went into this build again.
An x-ray tube is a simple device; a cathode emits electrons that strike a tungsten anode that emits x-rays. Most x-ray tubes, though, are relatively large with low-power mammography tubes being a few inches in diameter and about 6 inches long. In his amazing 45-minute-long video, [glasslinger] shows us how to make a miniature vacuum tube, a half-inch in diameter and only about four inches long.
For those of you who love glass lathes, tiny handheld spot welders and induction heaters, but don’t want your workshop bathed in x-rays, [glasslinger] has also built a few other vacuum tubes, including a winking cat Nixie tube. This alternate cat’s eye tube was actually sealed with JB Weld, an interesting technique if you’d ever like to make a real home made tube amp.
This AM radio looks a bit like it did coming out of the factory. But there are a lot of changes under the hood and that faceplate is a completely new addition. The project really is a restoration with some augmentation and [Michael Ross] did a great job of documenting the project.
The Kenyon radio was built in 1946 and uses vacuum tubes for the amplifier. Considering its age this was in relatively good shape and the first thing that [Michael] set out to do was to get the electronics working again. It involved replacing the messy collection of capacitors inside. He then cleaned up the tubes, checking for any problems, and put the electronics back together to find they work great!
He cleaned up the chassis and gave it a new coat of finish. The original dial plate was missing so he built a wood frame to match a dial scale he ordered. The bell-shaped brass cover hides the light that illuminates the dial.
He could have stopped there but how much do people really listen to AM radio these days? To make sure he would actually use the thing he added an Arduino with an MP3 shield. It patches into the antenna port via a relay, injecting modern tunes into the old amplifier circuit. Catch a glimpse of the final project in the video after the break.
Continue reading “AM tube radio restored and given MP3 playback too”
[Craig] did a great job of restoring the case of his antique console radio. But he wanted to bring the guts up to modern standards. The fix ended up being rather easy when it comes to hardware. He based his internet radio retrofit around a wireless router.
We laughed when we heard that he removed about eighty pounds of original electronics from this beast. He then cut a piece of MDF to serve as a mounting platform for the replacement hardware. The WiFi router takes care of audio playback from several sources and offers him the ability to control the stereo from a smart phone or a computer. It has a USB port to which he connected a hub to make room for the USB sound card and a thumb drive which holds his music library. The black box in the upper right is an amp which feeds the NHT stereo speakers housed in the lower half of the cabinet.
It doesn’t make use of the original knobs like the recent tube-amp conversion we looked at. But [Craig] did add some LEDs which illuminate the dial to help keep that stock look.
[James Glanville] wrote in to show of his latest tube project. It’s a clock using six IV-3 VFD tubes. In addition to the tube displays the project prominently features a blue 3D printed case which hides away all the guts of the build including the Stellaris Launchpad which drives the clock.
Speaking of guts, you’ll want to look through a few of [James’] other posts on the project. His first write-up on this clock shows off the protoboard and point-to-point soldering that makes the tubes work. To help simplify things he went with a MAX6921 VFD driver chip. He mounted it dead-bug style on its own piece of protoboard and then soldered all of the necessary connections to the larger hunk hosting the tubes. There’s also an interesting post that details the switch mode power supply which ramps the USB 5V power all the way up to the 50V used to drive the displays.
If you like this you should check out the first VFD clock he built. We featured it a while back in a links post.
While you won’t catch us in an argument with an audiophile regarding the sound quality of tube vs. solid state amps, there is a general consensus that tube amplifiers sound much better than their transistorized brethren. Actually building an all-tube amplifier, though, is a bit harder than one built around common ICs – there are transformers to deal with and of course very high voltages. One solution to get the sound of tubes easily but still retaining the simplicity of integrated circuits is a hybrid amp, or a tube preamplifier combined with a solid state power section. They’re easy enough to build as [Danilo] shows us with his hybrid tube amp design (Italian, translation).
[Danilo]’s design uses two ECC86 for the left and right channels powered by a 12 Volt supply. Each channel is sent through a tube and then amplified by a TDA2005 20 Watt power amplifier. After plugging in a CD player, the result is a clear, warm sound that can put a whole lot of power through a speaker.