Looks like the mechanical engineers trumped the EEs this time...
In the summer of 1965 while I was a student at Georgia Tech in Atlanta, I was living with several fraternity brothers near the Tech campus. One of our roommates, an electrical engineer major, had spent several weeks building an AM/FM stereo from a kit on the dining table. When he finally got the stereo working, he hooked it up to his big two cabinet speakers and was testing it by listening to a local FM radio station. After enjoying the music for a while, he discovered that he was missing something and left the house to go to Radio Shack and left the stereo playing.
We, Civil Engineering students and knowing nothing about electronics, decided to play a prank on him. While he was gone, we took the back off of one of the big cabinet speakers and put a small portable FM radio inside and replaced the back. The portable radio was tuned to the same FM station as his stereo and at about the same volume.
Later, when he came back and turned off the stereo to work on it, the one speaker kept on speaking. He stood there speechless, in his head he must have been going over all the technical possible causes of the speaker continuing to play. Thinking that the stereo must still be getting power, he immediately unplugged the power cord from the wall outlet but was surprised that the speaker kept speaking. Next he disconnected the speaker wires from the back of his stereo thinking this would surely fix the problem but the speaker still kept speaking. He then must have begun to conjecture about how some radio signal being induced into the speaker wires causing it to play. So he disconnected the speaker wires from the back of the speaker and was completely baffled when it kept speaking.
We knew the game was finally over when he went to his tool box and returned with a Phillips screw driver and began removing the back of the speaker. He was a little mad when found the portable radio blaring inside and knew that he had been the victim of our simple prank.
This is probably one of the simplest yet smartest pranks I have ever heard of. It is simple because of its execution, yet smart because it plays on the engineer's own knowledge of electronics to baffle him. I had a good chuckle thanks to this. The speakers that won't stop playing will be a good story to tell my other friends.
Daniel - http://taylormadeleadership.com
Reminds me of a story passed along from my grandfather, in the days when radio (like many today) meant crystal radio with headphones. He started working on it, and noticed that the sound didn't change. Removing the crystal, disconnecting the headphone wire, and finally removing the headphones. He then found his neighbor had just bought a brand-new (at the time) radio with loudspeaker.
A lovely scientific magic comedy. If i would have been there i would not have opened the cover. I just would have touched the cone paper of the speaker to feel the vibrations and identify or simple put my hear near the speaker grill and checked the direction of the sound coming.This would have given me an easy idea of what is in there.
The old adage - electronic engineers build weapons. Civil engineers build targets...
But you must concede that he found the problem in the usual manner of troubleshooting prowess. Be careful, his future bridges may shoot back...
This reminds me of another hidden object inside a radio. My now EX-wife was snooping through my collection of electronic goodies. She found a small multi-band radio that rattled when shaken. I suggested it probably had a broken ferrite rod antenna piece from being dropped at some time in its past history. Her suspicious detective instincts insisted that she had found where I kept my alleged hash stash hidden from her inside this radio.
I gave her the screwdriver and told her which way to twist the screws to open it up. Imagine her disappointment when the rattling object really was a piece of broken ferrite antenna rod.
The alleged hash stash was never found.
Soft starter technology has become a way to mitigate startup stressors by moderating a motor's voltage supply during the machine start-up phase, slowly ramping it up and effectively adjusting the machine's load behavior to protect mechanical components.
Products that fall under a CE marking Directive cannot be imported into the EU unless they show the CE marking, which is simply a manufacturer's self-declaration that the product complies with the relevant European legislation.