Shocking!


I had built an amp with a 60hz notch filter to try and measure my brainwaves. I wired up two copper pennies as probes and used a mixture of Jergens and salt as a conducting medium. I was using an AC power supply with a 15vdc output to drive the op-amps. I had a meter, an led, and a speaker connected to the output (I did not have an oscilloscope).

I plugged the wires from my temples into the op-amp inputs. At first all I heard was a very low 60hz buzz which I thought was coming from the speaker, but I also thought it strange I was not seeing anything on the led or meter.

"Damn, I thought I had that pesky 60hz filtered out. Oh well," I thought, "Perhaps a better contact between those pennies and my temples would help." So I pushed lightly on my temples. What happened next was really scary. I "heard" 60Hz coming from all directions, and "saw" brilliant blue flashes superimposed over my bedroom, and felt a slight tingling in my temples. I jumped up while ripping out the pennies with wires attached and sat there for about 30 minutes trying to see if I had any holes in my memory, or if I had lost any of my faculties.

After I had recovered, I examined the circuit and discovered that I had miswired it. Instead of connecting the pennies to the input, I had connected them across the power supply! The 60hz component was probably caused by the low impedance of my salted skull loading down the power supply.

Shocking!


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