Unusual functions of cheap parts
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From: Si Ballenger on 25 Nov 2005 20:50 On Fri, 25 Nov 2005 20:48:19 GMT, Al <no.spam(a)wanted.com> wrote: >In article <clieo1lq869ialc6um02omsfdt266dvr2c(a)4ax.com>, > Paul Keinanen <keinanen(a)sci.fi> wrote: > >> On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger <jono_1(a)bellsouth.net> >> wrote: >> >> >Take apart a couple of D cell carbon-zinc batteries. >> > >> >Wash off the carbon rods. Put each in a wooden clothes pin and connect the >> >attached ends to the mains voltage (US customers only, please). >> >> The problem is that the carbon rod conducts heat quite well, so after >> a while, any wooden object will catch fire :-). >> >> >Tap the free ends of the rods together. Move them apart as necessary. >> >> You must have quite slow fuses in 110 V land if you can do a reliable >> ignition without blowing the fuse. For 230 V operation, I would >> suggest using a current limiting resistor (such as a large heater) or >> an inductance (such as fluorescent light ballast) during the ignition. >> When there is a solid arc, the current limiter can be shorted out. >> >> Paul >> > >I would put a 100 watt lamp in series thereby limiting the current. I >would shave the ends down to points so they heated up rapidly. I put >them into a hollowed out fire brick and made a cheap furnace. Of course >don't look at it; it's like looking at the sun. The current limiter I saw used a glass pie pan with pieces copper metal on each side with salty water as the electrolyte. It would start to steam some when in operation. The furnace was a small clay flower pot with holes in each side with the carbon rods sticking inside until they touched.
From: Phil Hobbs on 25 Nov 2005 22:13 Si Ballenger wrote: >>I would put a 100 watt lamp in series thereby limiting the current. I >>would shave the ends down to points so they heated up rapidly. I put >>them into a hollowed out fire brick and made a cheap furnace. Of course >>don't look at it; it's like looking at the sun. > > > The current limiter I saw used a glass pie pan with pieces copper > metal on each side with salty water as the electrolyte. It would > start to steam some when in operation. The furnace was a small > clay flower pot with holes in each side with the carbon rods > sticking inside until they touched. > As a boy, I used an electric teakettle as a ballast for a two-D-cell carbon arc lamp--worked great. Cheers, Phil Hobbs
From: Ralph Barone on 26 Nov 2005 00:33 In article <no.spam-94A7B5.15482025112005(a)news.verizon.net>, Al <no.spam(a)wanted.com> wrote: > In article <clieo1lq869ialc6um02omsfdt266dvr2c(a)4ax.com>, > Paul Keinanen <keinanen(a)sci.fi> wrote: > > > On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger <jono_1(a)bellsouth.net> > > wrote: > > > > >Take apart a couple of D cell carbon-zinc batteries. > > > > > >Wash off the carbon rods. Put each in a wooden clothes pin and connect the > > >attached ends to the mains voltage (US customers only, please). > > > > The problem is that the carbon rod conducts heat quite well, so after > > a while, any wooden object will catch fire :-). > > > > >Tap the free ends of the rods together. Move them apart as necessary. > > > > You must have quite slow fuses in 110 V land if you can do a reliable > > ignition without blowing the fuse. For 230 V operation, I would > > suggest using a current limiting resistor (such as a large heater) or > > an inductance (such as fluorescent light ballast) during the ignition. > > When there is a solid arc, the current limiter can be shorted out. > > > > Paul > > > > I would put a 100 watt lamp in series thereby limiting the current. I > would shave the ends down to points so they heated up rapidly. I put > them into a hollowed out fire brick and made a cheap furnace. Of course > don't look at it; it's like looking at the sun. > > PS: I was 16 at the time ;-) I used a 0.5 or 0.7 mm pencil lead gently torqued down across the terminals of a regulated DC power supply. Set the current limit very low, crank the voltage up all the way and increase the current limit until the center of the lead starts glowing red. Due to the heatsinking effect of the binding posts, the lead will always heat up the most in the center, then the carbon will start to evaporate and the remaining lead will gradually neck down in the center until it is glowing white hot. As soon as the lead breaks in the middle, you convert from incandescent to carbon arc lamp, which usually surprises everybody watching. The arc is good for about 5 seconds until the voltage drop across the arc exceeds the capability of the power supply.
From: **THE-RFI-EMI-GUY** on 26 Nov 2005 00:59 I have also seen thermistors used as a self regulating thermal element for a crystal oven. Joe Leikhim K4SAT "The RFI-EMI-GUY" "Follow The Money" Pooh Bear wrote: >John Larkin wrote: > > > >>TO-220 bipolar transistors make nice temperature sensors. >> >> > >I like that trick. Esp the isolated tab type. > >Graham > > > -- Joe Leikhim K4SAT "The RFI-EMI-GUY" "Follow The Money"
From: Paul Keinanen on 26 Nov 2005 04:56
On Fri, 25 Nov 2005 12:29:52 -0800, Roy Lewallen <w7el(a)eznec.com> wrote: >Paul Keinanen wrote: >> . . . >> You must have quite slow fuses in 110 V land if you can do a reliable >> ignition without blowing the fuse. For 230 V operation, I would >> suggest using a current limiting resistor (such as a large heater) or >> an inductance (such as fluorescent light ballast) during the ignition. >> When there is a solid arc, the current limiter can be shorted out. >> > >Aren't you in danger of damaging your eyes from the UV emitted from the arc? Certainly. I used arc welding glasses when conducing these experiments. Some trivia: In the silent film era, actors had eye problems due to the UV radiation from arc studio lamps. Most of the usable illumination from the arc lights is actually from the glowing carbon electrodes. "Automatic arc lights" used a solenoid in series with the arc to keep the distance constant between the poles regardless of carbon electrode burnout. I assume that if this is to be used with a AC arc light, both the moving coil as well as the static coil should carry the arc current. Paul OH3LWR |