For an experiment with an Arduino I want to put some helium in a balloon, and I want to be able to put more gas in it, electronically. My idea was to do this with the help of a small gastube, ( < 1 L) and connect this gastube, with pressurized Helium in it to the balloon, with a valve in between, which I then again can control with the arduino. However, I can't find such a gas tube/ gas cylinder. Any help or comments on how or where to find such a cylinder?
Thanks!