Category Archives: vacuum tubes

Hackaday Prize Entry: Hot Logic

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A few weeks ago, [Yann] was dumpster diving and found something of interest. Two vacuum tubes, an ECC83S and an EL84. This was obviously the droppings of a local guitarist, but [Yann] wanted to know if he could build something useful out of them. An amplifier is far too pedestrian, so he settled on a vacuum tube computer.

The normal pentodes and triodes you’ll find in a tube amp require a lot of support components like output transformers, tube sockets, and high voltage power supplies. This was a little too complicated for a tube computer, but after a little bit …read more

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Resurrection — Pressing WW2 Radio Equipment Back into Service

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Mass production was key to survival during the Second World War. So much stuff was made that there continues to be volumes of new unpacked stuff left over and tons of used equipment for sale at reasonable prices. Availability of this war surplus provided experimenters in the mid 20th century with access to high performance test equipment, radio equipment, and high quality components for the first time.

Even today this old stuff continues to motivate and inspire the young generations because of its high build quality, unique electro-mechanical approaches, and overall innovative designs which continue to be relevant into the …read more

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Flying Close To The Flame: Designing Past Specified Limits

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A very good question came up on The EEVBlog forum that I thought deserved an in depth answer. The poster asked why would amplifier companies in the heyday of tube technology operate tubes in mass produced circuits well in excess of their published manufacturers recommended limits. The simple answer is: because the could get away with it. So the real question worth exploring is how did they get away with operating outside of their own published limitations? Let’s jump in and take a look at the collection of reasons.

Materials-Based Tube Performance

First a brief discussion of what the limiting …read more

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