Unusual functions of cheap parts
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From: Ron G on 25 Nov 2005 14:21 Our newspaper had an article on that. Also, for model rockets, burning up an ordinary resistor can be used as a super-cheap ignitor. Best--- Ron John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:361co1pavjfi56f0kmrm8phrtb64g2kmvo(a)4ax.com... > On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen > <jorgen.lund-nielsen(a)xxxxxxxxxxxxdesy.de> wrote: > > >Henry Kiefer 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 > > > >Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work > >well as medium fast Step Recovery Diodes. > > > >Jorgen > > > I know a guy who uses surface-mount resistors as explosive detonators. > > John > >
From: meow2222 on 25 Nov 2005 15:03 John Larkin wrote: > A 1N4007 can also be used as a drift step-recovery diode and as a > plasma avalanche diode. Together, two can generate a kilovolt edge > with a 100 ps risetime. > > GAASfets make good fast analog switches; they behave pretty much like > jfets. > > Wide-open LDO regulators make nice resettable fuses. > > Ferrite beads do all sorts of interesting stuff. > > Power mosfets make good heaters, and TO-220 bipolar transistors make > nice temperature sensors. > > LVDS line receivers are surprisingly good comparators, and *fast* > > > I could go on... > > John tell us more John NT
From: Roy Lewallen on 25 Nov 2005 15:29 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? Roy Lewallen, W7EL
From: Al on 25 Nov 2005 15:48 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 ;-)
From: Robert Obermayer on 25 Nov 2005 16:51
hi, sorry if you didnt like everything, but sometimes some voilence against parts that cost you half a day of time and gave you a bad headache while troubleshooting is necessary... For more useful things, FETs actually can work as quite useful one-component HF oscillators if wires and connection points are properly chosen.With a second transistor one can build a working shortrange AM transmitter. A rather useful (works perfectly for SMPS uses) AC current probe for a scope can be made by using a small UI cored RFI filter coil from a monitor, connecting its windings in series and terminating with a 1ohm resistor, to which a coax cable with BNC connector is soldered to. The wire you want to measure the current in simply is fed trough the core one time. This only gives quantitative measurements unless calibrated but can be very useful if you cant afford a real current probe. The known resonant royer circiut used for CCFL inverters can be used for larger inverters if appropriate parts are chosen, and can produce some high frequency/high voltage with a transformer from a old TV (with no internal rectifier). This has its uses, besides connecting it to a old light bulb that works as plasma globe or connecting both outputs to a large neon bulb [Bienenkorbglimmlampe], which simply looks very nice but also produces lots of RFI, so dont run it for too long. FET gate drivers make nice TTL output stages for function generators, as these can drive rather high currents and are fairly robust. If a slowly, steadily changing linear voltage is necessary (for ex. confirming the linearity of something) a 10turn precicion pot copuled with a slow syncronous motor (a old microwave oven has a nice 2.5u/min one) by some tape (so it slips/breaks when the pot is at its endpoint) works nicely. |