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    Doubt about laser power in laser transmitter

    If you are running a laser diode with enough current so you can see it yourself, you will should be able to detect it with almost any photodiode 100 meters away in decent conditions, easy!
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    How to let the cold work shape memory alloy to acquire shape memory properties

    I found it possible to be quite crude about it. I first wound the shape and clamped it, then ran a current through the wire until it relaxed. It did glow red.
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    The Nature of Colors

    Painters have to consider the light they work in and the lighting for display. One wishes to have a studio with north windows for solar spectrum indirect. A painter has a closed-loop system, though- he sees what it looks like and adjusts to suit, so I'm not sure these saturation effects...
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    Polymers with piezoelectric effect

    the commercial one used is vinyl fluoride, iirc. It's 'activated' at manufacture by cooling in a high electric field. physical movement from the piezoelectric effect is extremely tiny. you wouldn't be able to feel the expansion but you could feel vibration if you applied modulated power...
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    Making RC Controlled Objects

    If the question is how to get the motors on separate channels - and if you intend to use an ordinary IR remote controller, like for TV's and such- the way those work is that each button causes a serial code to be sent (in the ones I've used) on a 32KHz 'tone' (the IR LEDs are modulated at...
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    Monitoring a Live, 80W, 12VDC Load

    Lol. Good thing there are no psychologists replying - you'd hear about how to regress your amperage through hypnosis or something. Why not... wrap one of the power leads around a toilet paper derder? Then, turn on the power, set a cake pan under the derder and dump a handfull of paperclips...
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    Creating a conductive strip

    http://www.tedpella.com/SEMmisc_html/SEMadhes.htm#anchor1148917"
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    RFID masters project ideas

    An ingestible thermometer would be really useful for a project I'd like to do.
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    Homemade dynamometer

    It means don't use any controls in the circuit, just the nichrome resistance filament - the stove element is acting like a 1000W light bulb. A regular commercial element used below its rated capacity needs no cooling - in fact, you may wish to characterise its resistance at a stable working...
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    Crazy water pressure formula implication?

    I just stuck a piston in the column and I had most of a hydraulic jack. That cleared it up for me.
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    Help Design a Human-Powered Helicopter

    Do the rules prohibit offsetting the load with, say, lighter than air wings?
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    Robotic lawn mower

    Quite right. The typical set of variables, as in milling, is feed, speed, materials and number of teeth. In point of fact, however, the blades do virtually all their cutting on the outermost edge and the rest of the blade mostly provides unneccesary friction and a little shaft to wind crap up...
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    Robotic lawn mower

    Yes. DC motors can be speed controlled by pulse width modulation or by voltage, with feedback or without. You'll need to know more about the motors ratings to proceed with design. Higher voltages means more expensive.
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    Crazy water pressure formula implication?

    I think I get it now. It really does take that kind of pressure to lift that column. Thanks.
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    Crazy water pressure formula implication?

    I did the area and volume and 1 g/cc. You can't get PSI without putting Ps on top of SIs. When you add a tiny amount of mass, the sealed, enclosed horizontal surface where the little column empties represents the SI you added the minuscule fraction of a P to. At that level, every SI of the...
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    Robotic lawn mower

    You really need DC motors to be able to control speed. You can also regulate the load on the blades by enclosing them in a disk so only the ends do the cutting. The amount of exposed blade will determine the power required. Your main problem after that is coverage of area & boundaries. That's...
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    7 segment display in Multisim

    wrong thread, sorry
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    Trying to adapt a fuel gage circuit

    You can usually find data sheets here: http://www.datasheetcatalog.com/datasheets_pdf/T/L/0/8/TL082.shtml" If your output indicator will work on about 20 mA or less, it looks like tl082 should work. If you have an unused op amp, tie the inputs to something so it doesn't oscillate. digikey...
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    How to machine a NPT internal thread?

    I'm not sure what parameter you mean. NPT is a tapered pipe thread. http://en.wikipedia.org/wiki/National_pipe_thread" [Broken] That means it's made to guarantee interference at some depth. Usually the pipe will be wrapped with teflon tape to seal it as well. You can use a drill press...
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    Crazy water pressure formula implication?

    I calculate that the mass of water in the column is @ 0.078539816339744830961566084581988 grams at the base of the column (the surface of the enclosed sea), then, the pressure will be increased by that amount of mass divided by the total square inches of the surface covering the sea. (please...
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    How to machine a NPT internal thread?

    http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=313-3031&PMPXNO=2619722" with one of these?http://www.use-enco.com/ProductImages/7466334-11.jpg
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    Trying to adapt a fuel gage circuit

    http://img509.imageshack.us/img509/5784/invopamp.gif [Broken] There is a googleplex of sites with op amp tutorials for getting a basic understanding. Each company produces application notes for their devices showing lots of circuits. The example inverting op amp configuration, as shown, uses...
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    Trying to adapt a fuel gage circuit

    An op amp could solve this. With the inverting configuration, you need one pot to set offset - that's the baseline- and one pot to set gain - that's the range. That way you get perfect adjustment of the limits. LM386 is nice. http://www.national.com/mpf/LM/LM386.html#Overview [Broken]...
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    How to increase the abrasion resistance of rotor

    What about pressurised water to lubricate the seal?
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    Good way to test variable-speed generator output?

    You could cannibalize toasters, hairdryers or other used appliances for some nichrome resistance wire instead of buying a bunch of power resistors. You can stretch out segments for testing various loads.
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    How Could I do This? Motor to open and close doors on a timer?

    There must be a hundred ways that are cheap and trivial. You can get as elaborate as you'd like, too- incorporating temperature or humidity sensing can also be done cheap and dirty. At the extreme low end: battery powered clock guts which are sold for making clocks, with 2 contacts installed...
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    Creating an Air-Hockey table but to slide Tortilla Chips over

    Besides air, there are other possible solutions such as surface coatings, vibrating the chute, installing an oscillating rake or auger, making a circular chute that rotates.
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    555 timer internal schematic questions

    This is a passive voltage regulator circuit and is unable to increase current. Doubling current output can't be done passively, so perhaps a voltage regulator is not the best path to get you from here to where you want to be. The simplest solution to powering coils with a live supply may be...
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    YOU!: Fix the US Energy Crisis

    By golly... when you start questioning things you find out, eh? I'm still trying to get over the fact that it took me more than half a century to realize that the sun is not yellow but white. It's not like it was hiding from me all that time - I was guilty of believing without properly looking...
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    Magnetism & Engineering

    If you start out with a rapidly spinning wheel and videorecord it as the dynamic brake of the light slows it to a stop while you hold a carrot nearby, then you can reverse the clip and post it on youtube and get a few people to try wiggling a magic carrot around...lol. Sometimes the object is...
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    Wire Apparatus that Moves with Constant Speed Under Weight

    a centrifugal clutch may be one approach that needs no electronics
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    Making 4'x8' sign inkjet printer - need nozzles - help?

    If you want no guessing, print out a color wheel in real paint, by the numbers, and then code them into a lookup table. Raise and lower the applicator to eliminate streaking. Absorption can be tweaked and drying can be assisted with a hairdryer mounted on the printhead- or something more...
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    YOU!: Fix the US Energy Crisis

    I'm not finding the original thing I read, but here are links to more info. http://www.danielk.ca/2009/09/cogeneration-goes-residential-in-germany.html" http://www.oeko.de/oekodoc/579/2006-136-en.pdf" [Broken] This shows how great is the influence of ... um... collateral expenses that...
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    YOU!: Fix the US Energy Crisis

    I read that Germany proposes to install small, gas powered electric generators in individual homes. These will feed the grid on demand and the homeowners will make direct use of the exhaust heat for water and winter heating. The justification given was that it was far cheaper than adding a...
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    Steering Mechanism

    some thoughts- Control of a DC motor can be done with an optical encoder using quadrature output to clock a counter up or down. For pure digital control, a comparison is made to a control number sent and the motor is powered in the appropriate direction until the numbers match. There are some...
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    Help with a Basic design

    An electric automobile antenna mechanism sounds ideal for the little flagpole. If you are willing to hold the switch, then you are set right out of the junk yard. If it's to be one-touch button, then you need limit detection and some logic. If you use logic gates to control the 12v motor...
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    How would I create a time toggled switch in Multisim?

    place component source signal voltage source set to 1 Hz and appropriate voltage to toggle whatever you're toggling.
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    Making 4'x8' sign inkjet printer - need nozzles - help?

    This isn't exactly what you asked for, but it might still work for your purpose. An array of hypodermic needles can be used to deposit directly on a surface. With proper viscosity, the capillary forces will prevent dripping. Deposition is accomplished by piezoelectric vibrator + gravity &...
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    I'm curious about a number series

    This is an interesting type of number series I found. I have no idea if it's good for anything, but somehow it's captured my interest. the first example, the simplest is 0,1,1,0 the rules of operation are that you start at each position and take a pair of numbers. At the end, you wrap to...
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    Polygonal mirror reflection beam Problem

    Here are some thoughts. The very precisely made polygonal mirrors are salvaged from barcode scanners and available from electronic salvage suppliers. A jig can be made to resemble a faceting machine (google for a pic). You would start out with a reasonably true polygon and mount it on a...
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