Ferroucious writes –
In this instructable I’ll give you a simple way to collect Hydrogen gas and if you want also, to collect Oxygen. Depending on the voltage and current that you use for the project this could be hazardous. I used a 14.4 volt power drill battery pack for the process but don’t recommend it, I only used it to achieve a noticeable effect in a short time period (about 20 minutes).
instructables : Collecting Hydrogen and Oxygen – Link.