My first lesson in "capacitors store electricity" when I was a kid was when I took the battery out of a disposable camera... and then managed to shock myself with the flash discharge anyways.
I shocked myself a few times with these too, in the process of disassembling the cameras. I needed components (capacitors and the flash circuit) for the ignition system for the rocket engines we were building with a friend, so I went to a local photo store and asked nicely for used cameras with flash. They gave me a bag with some 20 of them.
(The shocks I got were through carelessness; I used a kitchen knife to discharge the caps after ripping off the plastic shell of the camera, but sometimes I touched the wrong thing while disassembling. Roughly half the cameras I got had the caps charged to the point they'd spark brightly on discharge, and one of them damaged the knife.)
Context for those too young to remember: back before digital cameras were available and affordable, you could buy disposable cameras in kiosks and stores cheaply. These would come pre-loaded with a single roll of film, and after you used it up (~30 photos), you'd take the whole camera to a photo store. The photo store people would rip the roll out of the camera, develop your photos, and throw the camera away. Some models came with flash, so if you could get the used ones from the store (or their trash), you got a free source of high-voltage capacitors.)
I used to work at radio shack. The rug behind the counter was very efficient at providing static electricity and whenever we touched the barcode scanning wand - zap. So I got a package of 2kv high voltage capacitors and held one lead while touching the other lead to the wand while rubbing my shoes on the carpet, thereby charging the capacitor. I left the charged capacitor on the POS terminal keyboard for the asshole I worked with to discover. Of course he fell right into my trap and picked up the capacitor. It was pretty funny to me, but not to him. This jerk would often steal my sales and talk down to me, he had it coming.
I did it by sticking a screwdriver where I shouldn't have and touching the flyback cap on an old (CRT) TV that was only recently unplugged. Luckily I wasn't well-grounded and the part of the screwdriver shunted the current turned to slag.
Did the same at a school trip, after taking off the film I thought I could tear the camera apart, thus exposing the cap connection. Left hand fingers would lean peeerfectly on these metallic parts when playing with the flash.
It became a game between kids. The shock was more intense than harmful, although I saw two white dots on my nail that I assumed was due to the shock.
Today I rip microwave ovens, but I carry gloves and remove caps before anything else.
We used a 5kV (DC) power supply for an A-Level physics experiment, and we quickly discovered that could give you a pretty unpleasant zap (peak current was ~3mA IIRC, so not particularly dangerous - one of our teachers initially insisted on us wearing latex gloves, until we demonstrated it arcing holes in them so it just gave you a false sense of safety). We also destroyed a fair number of multimeters that were allegedly rated for the voltage[1] - they started displayed obviously erroneous values.
I also discovered that accidentally holding a charged plate (thinking the supply was turned off) for a while could let you pick up tin foil just by holding your hand above it, which was pretty neat.
[1] IIRC we used a voltage divider to keep the maximum voltage around 500V, and the meters were rated for 1000VDC.
ocdtrekkie|5 years ago
TeMPOraL|5 years ago
(The shocks I got were through carelessness; I used a kitchen knife to discharge the caps after ripping off the plastic shell of the camera, but sometimes I touched the wrong thing while disassembling. Roughly half the cameras I got had the caps charged to the point they'd spark brightly on discharge, and one of them damaged the knife.)
Context for those too young to remember: back before digital cameras were available and affordable, you could buy disposable cameras in kiosks and stores cheaply. These would come pre-loaded with a single roll of film, and after you used it up (~30 photos), you'd take the whole camera to a photo store. The photo store people would rip the roll out of the camera, develop your photos, and throw the camera away. Some models came with flash, so if you could get the used ones from the store (or their trash), you got a free source of high-voltage capacitors.)
leptons|5 years ago
thelazydogsback|5 years ago
agumonkey|5 years ago
It became a game between kids. The shock was more intense than harmful, although I saw two white dots on my nail that I assumed was due to the shock.
Today I rip microwave ovens, but I carry gloves and remove caps before anything else.
stordoff|5 years ago
I also discovered that accidentally holding a charged plate (thinking the supply was turned off) for a while could let you pick up tin foil just by holding your hand above it, which was pretty neat.
[1] IIRC we used a voltage divider to keep the maximum voltage around 500V, and the meters were rated for 1000VDC.