tubes

27 Articles

Rebuilding A 1940s TV

October 18, 2013 by 30 Comments

TV

There’s a lot of cool stuff to be found under piles of trash in an antique store. [dijt] discovered this when he found a tiny 7″ Motorola television from the 1940s under a stack of trinkets from earlier eras. We can understand [dijt]’s impulse buy, and the trials of rebuilding this ancient TV more than qualifies it as a hack.

If you know where to look, there are hundreds of resources available for old televisions, Hi-Fis, and radio equipment from the dawn of the electrical era to the modern day. After consulting with a few forums, [dijt] got his hands on a schematic for his television set and began work on diagnosing what was wrong with it.

It turned out the original ballast tube in this set had long since given up the ghost. Luckily, this is a common problem in old TVs, and after consulting some forums [dijt] had a schematic to replace this ballast tube with some newer caps and resistors.

After constructing the circuit and testing it out, [dijt] mounted it in the old ballast tube to replicate the original look and feel of the 1949 television. Interestingly, this is the second time this TV had been restored; the 1960s-era caps and resistors told [djit] this TV had once went into a television repair shop. Let’s just hope [djit] remembered to glue the schematics to the inside of the chassis this time.

High Voltage Hacks: A 1000 Watt Tube Amp

August 26, 2011 by 26 Comments

Normally when we hear of a Champ guitar amp, we think of a sweet-sounding rig that puts out 6 Watts through an 8-inch speaker. [John Chambers] of Champ Electronics wanted to build a true champion for the field of battle and came up with The Champ 1000 Watt Tube Amp, an amplifier that probably puts out enough heat to keep an igloo warm.

The amp is based on 807 valves. With some clever engineering [John] managed to coax 100 watts out of a pair of 807s, so the entire amp “only” requires 20 power tubes. The build log shows some pretty impressive examples of electrical prowess. We can’t recall the last time we featured a build with point-to-point wiring on tagboard, and [John]’s work is some of the best we’ve ever seen.

[John] has been working on this amp off and on for a few years now, but he should be wrapping up the build sometime soon. We haven’t seen this amp in action, but we imagine it would look something like this 36×10 monstrosity. Send us a message or post a comment if you can find a video and we’ll put it up.

Tube Amp Monitor

June 23, 2008 by 5 Comments


Sparkfun contributor [Pete] really loves tube amps, but he’s a very safety-conscious guy who doesn’t like being electrocuted. This is a problem, since tube amps are usually very high voltage, and a small mistake can be fatal. To deal with this voltage issue, he built a tube amp with a control system built around a 6DOF v3 controller board. The control system is there mainly in case of a failure, automatically shutting off the high voltage transformer in any such event. It has the added benefit of filtering any 60Hz noise from getting into the audio, which happened before he installed the control system.

In addition to regulating power, the controller board also monitors bias points in the output tubes and displays its diagnostics on an LCD. Aside from getting great sound from the tube amp, [Pete] made it look great too, installing colored LEDs under the tubes. We love his design: just because safety comes first it doesn’t mean cool-factor can’t come in a close second.

Multiband Nixie VU Meter

June 13, 2008 by 4 Comments


This VU meter project by [Daniel Naito] is a great piece of Russian electrocouture. It’s made up of 14 Nixie tubes that display seven frequency bands for the two audio channels. He found this similar project, but wanted to keep the cost low by avoiding such exotic ICs. First, the two input channels are amplified and then split using seven bandpass filters covering 60, 150, 400, 1000, 2500, 6000, and 15000Hz. Then, the AC audio is converted to DC. The final stage converts the logarithmic scale to a linear output. Besides the semirare Nixie tubes, the majority of the parts are just cheap opamps and comparators. The post is an excellent read and you can see it in action in the video below.

UPDATE: Yep, it’s a repost. I’m awesome like that. The True RMS Plasma Vu-meter seems to be new to us though.

Continue reading “Multiband Nixie VU Meter” →

Nixie Tube VU Meter

March 27, 2008 by 15 Comments


[Daniel] sent in his Nixie tube VU meter. It uses 14 Russian IN-13 Nixie bar-graph tubes. He built a custom circuit to amplify, filter, smooth and feed a voltage divider to assign signal levels to segments and finally some high voltage transistors to drive the tubes. The circuit looks pretty big, but it’s repeated for each tube – so he worked hard to keep the cost down as much as possible. Now this just needs to live on the front of a massive tube amplifier.