Vacuum gauge

Estimate reading time: < 1 minute

For the rough measuring we can use a common manometer, for more exact measurement at lower pressures, it is necessary to use a gauge for high vacuum. As expected, such a thing is pretty expensive, so I look for some diy solution and I found 😉 It is called Pirani gauge, it consists of one perforated bulb and some simple electronic. The electronics I chose was Sooty’s one. It is simple, cheap and easy to build.. I took a 24v/1.2W, cold resistance 46 Ω. I wasted 3 of 4 I have at home 🙁 I perforated the bulb using a tungsten wire (0.6 mm) by heating it up in flame and pricking it into the bulb. Don’t heat the bulb (at least not much) otherwise it deflate because of its lower pressure.

I tried to melt the bulb and tube together, but it cracked during cooling, probably because of different thermal expansion coefficient of glass tube and the bulb. So the next try (with another bulb) was to seal it into tube by hot glue. I hope it won’t evaporate any vapours when evacuated. It is just some kind of plastics, so who know..