Body Detector

I have been designing a "body detector". This uses two high-frequency oscillators, so I needed to hard-wire (almost) everything. Which is risky. It takes only one slip to destroy everything. I thought, therefore, when I was done -- and it failed to work -- that I had in fact ruined it. It wasn't my circuit, though, that had failed. First, the clips to the battery failed. Second, the piezo buzzer failed. That's two manufactured items which didn't make the grade. Then, the (next) piezo buzzer went click-click instead of beeping. I double-checked. My theory was correct. My wiring looked perfect. It was the buzzer which needed special conditions to sound. OBSERVATION: Which shows just how much can go wrong without it being due to design or construction. I expect to make a video to demonstrate the body detector here.