Whenever you do any divination like this, it is probably worthwhile being extra vigilent with regards to your spiritual self-defense and protection procedures.
In my experience, there is no doubt that a pendulum works and can be pretty much reliable "most" of the time. My wife uses one occasionally. We also use Angel card decks from time to time.
Would it not be better to cultivate your inner-dialogue and get your answers that way? It is much faster
A..