There have been a lot of half-baked or just plain cockeyed schemes proposed here lately. With most of them, I try to offer patient explanation or at least thought-provoking kibitzing. I figure I owe that as payback. One afternoon when I was around eight years old, I made a telegraph sounder. I drove a nail into one side of half a broken yoyo, cut a Z-shaped piece of iron from a tin-can lid and tacked it opposite so that the nail -- my electromagnet -- would pull it down and make a click. Then I wrapped maybe two dozen turns of bell wire around the nail, bared the ends, and shoved them into a 110V outlet. It actually did click as the lights went out. All the lights. I has blown the main fuse (30A service, single phase). I didn't know there was a main fuse, but fortunately, my uncle came over to get a tool and he replaced it before it got dark out. Then he took the time to sit me down and explain about impedance and such, adding to what I knew about circuits. When I built an electric-arc furnace, I used an electric iron as ballast. I blew the main fuse again anyway (how?), but I knew how to replace it. Every little bit helps. I try to do my bit. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
sorta OT: A little knowledge is a dangerous thing.
Started by ●June 3, 2008
Reply by ●June 3, 20082008-06-03
Jerry Avins wrote:> There have been a lot of half-baked or just plain cockeyed schemes > proposed here lately. With most of them, I try to offer patient > explanation or at least thought-provoking kibitzing. I figure I owe that > as payback. > > One afternoon when I was around eight years old, I made a telegraph > sounder. I drove a nail into one side of half a broken yoyo, cut a > Z-shaped piece of iron from a tin-can lid and tacked it opposite so that > the nail -- my electromagnet -- would pull it down and make a click. > Then I wrapped maybe two dozen turns of bell wire around the nail, bared > the ends, and shoved them into a 110V outlet.Y'know, when I took the house power down it was because I _knew_ that a short circuit was going to create a big ball of fire -- so I had the twisted-together end of the lamp cord in a coffee can for safety. Boy was I surprised when the lights in the room went out quietly. And boy did I have that "uh oh" feeling when I realized that I'd turned off half the house.> It actually did click as the lights went out. All the lights. I has > blown the main fuse (30A service, single phase). I didn't know there was > a main fuse, but fortunately, my uncle came over to get a tool and he > replaced it before it got dark out.For me it was my dad. Kids live to be engineers by the grace of their older relations.> Then he took the time to sit me down and explain about impedance and > such, adding to what I knew about circuits. When I built an electric-arc > furnace, I used an electric iron as ballast. I blew the main fuse again > anyway (how?), but I knew how to replace it. >Now, I can't figure that one out unless you had it on the other end of a step-up transformer, or if it wasn't warming up enough to really limit the current. So, I'll bite -- how? -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
Reply by ●June 3, 20082008-06-03
Tim Wescott wrote:> Jerry Avins wrote: >> There have been a lot of half-baked or just plain cockeyed schemes >> proposed here lately. With most of them, I try to offer patient >> explanation or at least thought-provoking kibitzing. I figure I owe >> that as payback. >> >> One afternoon when I was around eight years old, I made a telegraph >> sounder. I drove a nail into one side of half a broken yoyo, cut a >> Z-shaped piece of iron from a tin-can lid and tacked it opposite so >> that the nail -- my electromagnet -- would pull it down and make a >> click. Then I wrapped maybe two dozen turns of bell wire around the >> nail, bared the ends, and shoved them into a 110V outlet. > > Y'know, when I took the house power down it was because I _knew_ that a > short circuit was going to create a big ball of fire -- so I had the > twisted-together end of the lamp cord in a coffee can for safety. > > Boy was I surprised when the lights in the room went out quietly. And > boy did I have that "uh oh" feeling when I realized that I'd turned off > half the house. > >> It actually did click as the lights went out. All the lights. I has >> blown the main fuse (30A service, single phase). I didn't know there >> was a main fuse, but fortunately, my uncle came over to get a tool and >> he replaced it before it got dark out. > > For me it was my dad. Kids live to be engineers by the grace of their > older relations.I learned enough to make the sounder from my father. That was the dangerous little bit of knowledge. My uncle was an EE who moonlightes rewiring houses. I was often his assistant. Trouble was, he had leather fingers and acted as if everyone else did too. He would test a lamp socket by sticking his finger in it. If he wasn't sure, he would wet the finger.>> Then he took the time to sit me down and explain about impedance and >> such, adding to what I knew about circuits. When I built an >> electric-arc furnace, I used an electric iron as ballast. I blew the >> main fuse again anyway (how?), but I knew how to replace it. >> > Now, I can't figure that one out unless you had it on the other end of a > step-up transformer, or if it wasn't warming up enough to really limit > the current. > > So, I'll bite -- how?I'm still wondering! The next time I tried it, my father had already put in 60A 2-phase service. Dang! I melted a crucible of copper! Whooee! Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 4, 20082008-06-04
On Jun 3, 6:26�pm, Jerry Avins <j...@ieee.org> wrote:> Tim Wescott wrote: > > Jerry Avins wrote: > >> There have been a lot of half-baked or just plain cockeyed schemes > >> proposed here lately. With most of them, I try to offer patient > >> explanation or at least thought-provoking kibitzing. I figure I owe > >> that as payback. > > >> One afternoon when I was around eight years old, I made a telegraph > >> sounder. I drove a nail into one side of half a broken yoyo, cut a > >> Z-shaped piece of iron from a tin-can lid and tacked it opposite so > >> that the nail -- my electromagnet -- would pull it down and make a > >> click. Then I wrapped maybe two dozen turns of bell wire around the > >> nail, bared the ends, and shoved them into a 110V outlet. > > > Y'know, when I took the house power down it was because I _knew_ that a > > short circuit was going to create a big ball of fire -- so I had the > > twisted-together end of the lamp cord in a coffee can for safety. > > > Boy was I surprised when the lights in the room went out quietly. �And > > boy did I have that "uh oh" feeling when I realized that I'd turned off > > half the house. > > >> It actually did click as the lights went out. All the lights. I has > >> blown the main fuse (30A service, single phase). I didn't know there > >> was a main fuse, but fortunately, my uncle came over to get a tool and > >> he replaced it before it got dark out. > > > For me it was my dad. �Kids live to be engineers by the grace of their > > older relations.For me it was when i stuck two ends of a wire into the wall outlet. i thought something would happen, but sparks and blown fuse wasn't what it was. i gotta tell you that that was only one of many instances where my guardian angel covered my ass. i've done enough careless/ clueless experiments, it's sometimes curious how i lived to this day. (my guardian angel can kick the butt of nearly any other guardian angel.)> I learned enough to make the sounder from my father. That was the > dangerous little bit of knowledge.thanks for being explicit, Jerry. i wasn't making the connection.> My uncle was an EE who moonlightes > rewiring houses. I was often his assistant. Trouble was, he had leather > fingers and acted as if everyone else did too. He would test a lamp > socket by sticking his finger in it. If he wasn't sure, he would wet the > finger.did he have to walk barefoot through the snow 6 miles every day to get to school? :-)> >> Then he took the time to sit me down and explain about impedance and > >> such, adding to what I knew about circuits. When I built an > >> electric-arc furnace, I used an electric iron as ballast.???? all i can think of is putting the electric iron into monstrous blackjack. add a little ballast to it.> I blew the > >> main fuse again anyway (how?), but I knew how to replace it. > > > Now, I can't figure that one out unless you had it on the other end of a > > step-up transformer, or if it wasn't warming up enough to really limit > > the current.oh, now i know what you mean. L8r, r b-j
Reply by ●June 4, 20082008-06-04
It seemed like all I could do was to make pits. There was the pit in the kitchen faucet where I'd stabbed it with a test probe connected to the 120vac. This was part of an experiment in the resistance of water with various amounts of salt in it - in series with a light bulb. The probes generally went into the salt water. One variation and a mistake and I grounded out the hot side to the faucet - on purpose but not the way it ended up. Welded the probe to the faucet and left a pit. There was the pit in my finger from an RF burn. I started with a CW transmitter and had a DPDT open knife switch for an antenna TR switch. The sequence was: put the switch in receive mode, listen, decide to transmit, throw the switch, start transmitting, stop transmitting, throw the switch, listen, .... With CW there was no power on the switch unless the key was down. Then I switched the transmitter to AM. No change to the switch but now the key was replaced by a microphone and a transmit switch on the transmitter. Same sequence was desired but now one had to turn on the transmitter instead of press the key and one had to grab the mic. Get it out of sequence at the end of a transmission and: one hand on the mic and one hand on the hot switch! Reflexes fortunately sent the mic flying across the desk (twice). Deep pit in my finger! Shook my shoulders really hard. Fred
Reply by ●June 4, 20082008-06-04
Amazing how nearly all of these stories involve making sparks with 120VAC. In my case, it was an extension cord. The male end was intact, but where the female end should have been was just bare wires. I stuck the male end into an outlet on one side of the living room, the bare wires into an outlet on the other side of the room. I had a 50:50 chance of nothing happening, an equal chance of sparks a-flyin'. Much to my delight, I got the sparks. The breaker did NOT trip. My mother ran into the room, "Greg!!! What did you do?" With a huge grin on my face, I said, "This ..." and did it again. Greg
Reply by ●June 4, 20082008-06-04
robert bristow-johnson wrote:> On Jun 3, 6:26 pm, Jerry Avins <j...@ieee.org> wrote: >> Tim Wescott wrote: >>> Jerry Avins wrote: >>>> There have been a lot of half-baked or just plain cockeyed schemes >>>> proposed here lately. With most of them, I try to offer patient >>>> explanation or at least thought-provoking kibitzing. I figure I owe >>>> that as payback. >>>> One afternoon when I was around eight years old, I made a telegraph >>>> sounder. I drove a nail into one side of half a broken yoyo, cut a >>>> Z-shaped piece of iron from a tin-can lid and tacked it opposite so >>>> that the nail -- my electromagnet -- would pull it down and make a >>>> click. Then I wrapped maybe two dozen turns of bell wire around the >>>> nail, bared the ends, and shoved them into a 110V outlet. >>> Y'know, when I took the house power down it was because I _knew_ that a >>> short circuit was going to create a big ball of fire -- so I had the >>> twisted-together end of the lamp cord in a coffee can for safety. >>> Boy was I surprised when the lights in the room went out quietly. And >>> boy did I have that "uh oh" feeling when I realized that I'd turned off >>> half the house. >>>> It actually did click as the lights went out. All the lights. I has >>>> blown the main fuse (30A service, single phase). I didn't know there >>>> was a main fuse, but fortunately, my uncle came over to get a tool and >>>> he replaced it before it got dark out. >>> For me it was my dad. Kids live to be engineers by the grace of their >>> older relations. > > For me it was when i stuck two ends of a wire into the wall outlet. i > thought something would happen, but sparks and blown fuse wasn't what > it was. i gotta tell you that that was only one of many instances > where my guardian angel covered my ass. i've done enough careless/ > clueless experiments, it's sometimes curious how i lived to this day. > (my guardian angel can kick the butt of nearly any other guardian > angel.)I don't know about that. I once decided to see how concentrated I could make hydrogen peroxide. My last measurement showed something over 80%. I had planks rigged so the force of the explosion went over my head. Just.>> I learned enough to make the sounder from my father. That was the >> dangerous little bit of knowledge. > > thanks for being explicit, Jerry. i wasn't making the connection. > >> My uncle was an EE who moonlighted >> rewiring houses. I was often his assistant. Trouble was, he had leather >> fingers and acted as if everyone else did too. He would test a lamp >> socket by sticking his finger in it. If he wasn't sure, he would wet the >> finger. > > did he have to walk barefoot through the snow 6 miles every day to get > to school? > > :-)I don't know, but they used to keep small pots of concentrated sulphuric acid between the inner and outer windows to keep them from fogging inside. It was cold enough in winter so people drove wagons across the frozen river that ran through town.>>>> Then he took the time to sit me down and explain about impedance and >>>> such, adding to what I knew about circuits. When I built an >>>> electric-arc furnace, I used an electric iron as ballast. > > ???? all i can think of is putting the electric iron into monstrous > blackjack. add a little ballast to it.A series current limiter, like the inductive ballast in fluorescent lamps. If my mother's iron didn't blow the fuse when plugged in alone, why would it when in series with the arc?>> I blew the >>>> main fuse again anyway (how?), but I knew how to replace it. >>> Now, I can't figure that one out unless you had it on the other end of a >>> step-up transformer, or if it wasn't warming up enough to really limit >>> the current. > > oh, now i know what you mean.Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 4, 20082008-06-04
On Jun 4, 9:16�am, Jerry Avins <j...@ieee.org> wrote:> > A series current limiter, like the inductive ballast in fluorescent > lamps. If my mother's iron didn't blow the fuse when plugged in alone, > why would it when in series with the arc? >My Dad used to swear that he could build a decent arc welder using an old stove burner in series with the welding rod. I don't think he ever did, though. Seems like that would put 220 VAC (at least 110 volts above ground) on the rod whenever the arc was broken. I guess you could do it if you were careful about where you put stuff.
Reply by ●June 4, 20082008-06-04
John Hadstate wrote:> On Jun 4, 9:16 am, Jerry Avins <j...@ieee.org> wrote: >> A series current limiter, like the inductive ballast in fluorescent >> lamps. If my mother's iron didn't blow the fuse when plugged in alone, >> why would it when in series with the arc? >> > > My Dad used to swear that he could build a decent arc welder using an > old stove burner in series with the welding rod. I don't think he > ever did, though. > > Seems like that would put 220 VAC (at least 110 volts above ground) on > the rod whenever the arc was broken. I guess you could do it if you > were careful about where you put stuff.I once arc welded a broken bell crank from a throttle linkage by winding one jumper cable through a tire rim to make an inductive ballast, then holding the bell crank on one battery terminal and a piece of hanger wire connected to the other terminal through the other jumper cable. Three pairs of sun glasses were not really enough and the weld was lumpy, bit it got us home. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 4, 20082008-06-04
On Jun 4, 3:01 pm, Jerry Avins <j...@ieee.org> wrote:> John Hadstate wrote: > > On Jun 4, 9:16 am, Jerry Avins <j...@ieee.org> wrote: > >> A series current limiter, like the inductive ballast in fluorescent > >> lamps. If my mother's iron didn't blow the fuse when plugged in alone, > >> why would it when in series with the arc? > > > My Dad used to swear that he could build a decent arc welder using an > > old stove burner in series with the welding rod....> I once arc welded a broken bell crank from a throttle linkage by winding > one jumper cable through a tire rim to make an inductive ballast,i once made a simple arc welder outa a fully charged car battery (shop class in high school). voltage was a little low, but i could get about as much current as i needed. i imagine a parallel circuit of a few pairs of car batteries in series would give you enough juice to weld anything. kinda hard to control. r b-j
