There you are at the surplus store, staring into the bin of faded orange, yellow, red, and black, boxes–a treasure trove of vintage vacuum tubes—dreaming about building a tube amp for your guitar or a phonograph preamp for your DIY hi-fi sound system. But, if you are not already in possession of a vintage, purpose-built tube testing device, how would you test them to know whether they are working properly? How would you test out your designs before committing to them? Or maybe your goal is simply to play around and learn more about how tubes work.
One approach is to build yourself a breadboard for tubes, like [MarceloG19] has done. Working mostly with what was laying around, [MarceloG19] built a shallow metal box to serve as a platform for a variety of tube sockets and screw terminals. Connecting the terminals to the socket leads beneath the outer surface of the box made for a tidy and firm base on which to connect other components. The built-in on/off switch, fuse and power socket are a nice touch.
[MarceloG19’s] inaugural design is a simple Class A amplifier, tested with a sine wave and recorded music. Then it’s on to some manual curve tracing, to test a tube that turns out to be fairly worn-out but serviceable for certain use cases.
If you’re dipping your toes into tube-based electronics, you’re going to want a piece of equipment like this prototyping board and [MarceloG19’s] documentation and discussion are a good read to help get you started.
Once you have your board ready, it’s time to move on to building a stereo amplifier , a tube-based headphone preamp, or take things in a different direction with this CRT-driven audio amplifier.
“surplus store”?! Where is this mythical beast?
Here in Germany it’s that shop where you can order 1 kg of random parts for 7.99€. They’ll send you 10 random tubes for 1.95€.
I expect that most Western cities have at least one electronics surplus shop of some description, with flats of unsorted, untested tubes. Tube lots can occasionally be found in the local online classified ads, after someone’s reclusive uncle passes away. And of course tubes are found on fleaBay. And amateur radio (“ham”) groups periodically have flea markets at which tubes are usually available.
Several years ago, new old-stock mil-spec Soviet tubes were very cheap on eBay, so I stocked up. Great for audio and radio projects. They’re still available, but not as cheap. The very small pencil tubes with leads are still inexpensive.
My approach was to take cut leads from diodes that were either used in projects or no longer identifiable and solder those unto Sockets. These could be bent to fit in a regular breadboard. It isn’t remotely elegant or proper, but it is good enough for experiments like running tubes at lower than intended voltages and so called “Hybrid” amplifier circuits.
i use flexibe wire and a pin header for that. the tube lies flat down besides the breadboard.
“tubes” as in not CRT’s, are known in English as valves 😉
Who here is old enough to remember the origins of the term “breadboard”?
Also, I was thinking those terminal blocks could be replaced by springs, like those in a RadioShack 100-in-1 kit.
I am, and that’s why mine was made with an old wooden clipboard. Banana jacks for power input, several terminal blocks, a long solid copper bus bar (for tack soldering to), and octal relay sockets with screw terminals.
I just use tagboard
i have something similar. in general I’ll avoid metal for the base I’ll prefer something more ‘isolated’ (i had one made with wood probably plexiglass would be better)
I see the word bread board… But no bread 🤔
Probably better than metal. Vacuum tube (9 pin) prototyping board enclosure by simplyflipflops – Thingiverse https://share.google/kndBfJvHosC5bSKJ7