When I was in high school (many decades ago now) we had a vacuum tube tester with a switch that allowed you to select the heater voltage. We quickly discovered, devils that we were, that if you stuck a simple diode with a 1.5 V heater in the tester and cranked the voltage to max it would launch like a little rocket. Eye protection recommended.
"We quickly discovered, devils that we were, that if you stuck a simple diode with a 1.5 V heater in the tester and cranked the voltage to max it would launch like a little rocket."
Where I once worked we had several AVO Mk III valve testers† which we used in a nice little "demo" (for want of a better word) for both new employees and non-electronics types who'd occasionally wander into the engineering/electronics department.
We'd take a 7 or 9-pin miniature valve (preferability 9-pin) and place it under water and break the evacuating seal on its top, being evacuated the valve would instantly fill with water. Now with suitable settings on the AVO we'd get the water to boil with steam bubbling out of its top. This all happened whilst we nonchalantly went about our business pretending that nothing unusual was happening.
Sometimes the reaction from the newcomers/visitors was so funny that those of us who couldn't keep a straight face would quickly exit the lab and burst into hysterical laughter.
That was party trick number one, there were more: half fill a CRT with water by the same process and put it back into the monitor for some poor unsuspecting tech to discover. Another was our famous CO2-powered valve gun which we'd use to shoot 7-pin and 9-pin valves at high speed across the carpark aimed at the door of the electricians' department with whom we were continually at war. The valves would embed themselves in the wooden door up to the full length of their pins and rarely would the glass break. Electricians would come in next morning to find our little gifts awaiting them.
Yet another was the exploding electrolytic capacitor under one's seat. And there are many more to tell.
Believe it or not, we were quite a professional outfit and our work output was excellent. But it was the funniest and most enjoyable place I've ever worked at.
