Unusual functions of cheap parts
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From: Jim Thompson on 26 Nov 2005 10:55 On Fri, 25 Nov 2005 22:13:38 -0500, Phil Hobbs <pcdhSpamMeSenseless(a)us.ibm.com> wrote: >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 I've used a light bulb in series with a rectifier to charge a car battery (just make sure that line ground goes to chassis ground ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: martin griffith on 26 Nov 2005 11:12 On Thu, 24 Nov 2005 09:40:27 +0100, in sci.electronics.design "Henry Kiefer" <otc_friend(a)gmx.net> wrote: >Hi all - > >After my first thread going from "standard" cheap parts for up to vhf >frequency to a discussion about the usefulness of Spice simulator...... I >try it another time hopefully get attention of frustrated co-readers: > >For example the rechtifier diode 1N4007 can be used as a rf switching diode, >for example as rx/tx-switch. This is because it is a pin structure diode. >This type is cheap and you can get it almost everywhere. It shows good >performance for the price. Surely for high-end you should do it with another >type tuned to the application it is made for. But anyway it works in some >circuits. > >Do you know of other interesting devices or circuits good for misuse? > >Best regards - >Henry > Switching a 20 year old 24v weller soldering iron on and off is a good test for seeing if an 8051 cpu board is EMC proof martin
From: Matthias Weingart on 26 Nov 2005 11:16 John Devereux <jdREMOVE(a)THISdevereux.me.uk> wrote in news:8764qh82fw.fsf(a)cordelia.devereux.me.uk: > ehsjr <ehsjr(a)bellatlantic.net> writes: >> Henry Kiefer wrote: >> > Do you know of other interesting devices or circuits good for >> > misuse? Best regards - >> > Henry >> >> An LED as a shunt regulator. Also, as a varicap. >> Ed > > Also a photodetector that is insensitive to long wavelengths > (because of the high bandgap). To save power, use the LEDs of a backlight to measure the ambient light to decide to switch the backlight on or not. M. -- Bitte auf mwnews2(a)pentax.boerde.de antworten.
From: John Larkin on 26 Nov 2005 13:28 On Sat, 26 Nov 2005 11:56:55 +0200, Paul Keinanen <keinanen(a)sci.fi> wrote: >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 We worked with a company that was developing an xray imager, and was buying very expensive electrically conductive glass (gigohms per square sort of range.) They discovered that certain welding glass was identical and about 1/20 the price. John
From: Winfried Salomon on 26 Nov 2005 15:41
Hello Jorgen, Jorgen Lund-Nielsen wrote: [.....] > 2N2369 for fast pulses. btw, do you know a standard complementary pnp-transistor for the 2N2369, such like 2N3905 but with higher ft and less feedback capacitance? It seems that the manufactorers have almost no data on their internet pages. mfg. Winfried |