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  1. hevans1944

    Question about A/C electricity

    Three wires are used in two instances. One instance is ordinary house wiring, where one wire (white) is the "neutral" or AC return wire; a second wire (black or red) is the "hot" or AC supply wire; and a third wire (green) is the "safety" ground wire. Each "hot" or AC supply wire is supplied...
  2. hevans1944

    What type of battery is good for emergency power for blackouts?

    Go back and read posts #10 and #12. Alternators are not "tuned" AFAIK. Their output voltage is a relatively simple function of shaft speed and rotor (exciter) current. You might ask yourself why alternators replaced generators in automobiles in the 1950s. The engine speeds didn't change, and...
  3. hevans1944

    Building an analogue wind direction meter

    I found another sensor that looks promising and potentially inexpensive. This one is based on sensing the thermal gradient across a centrally heated surface to calculate both wind speed and wind direction: Accuracy and resolution appears mediocre compared to rotating-cup anemometer and wind...
  4. hevans1944

    What type of battery is good for emergency power for blackouts?

    That's what this forum is all about. A used bicycle and a used alternator pulled from a wrecked car should put you in business. Maybe get a tandem bicycle built for two riders, so you can sell the excess power generated.:p
  5. hevans1944

    Building an analogue wind direction meter

    Hmm. You might be able to "get by" with just four "tunnels" with two pairs, each pair at right angles to the other pair. You might have to restrict the air flow out one end to differentiate which direction the wind is blowing from. I will continue to "research" the Internet for already existing...
  6. hevans1944

    Building an analogue wind direction meter

    The rate of heat loss from each hot wire is dependent on how fast the wind flows past each wire, so @Alec_t is correct: if all the wires are in the same wind then they should all lose heat at the same rate, regardless of wind direction. My bad for not thinking this through. Perhaps each of four...
  7. hevans1944

    What type of battery is good for emergency power for blackouts?

    A big Mac contains about 563 calories. One calorie of food energy is equal to 1.16 watt-hours. When I do the math, it tells me that if I were to get into excellent shape and pedal hard to generate 100 watts of power, then after an hour of pedaling, my big Mac meal would provide me with 563 x...
  8. hevans1944

    Building an analogue wind direction meter

    A synchro (or selsyn) pair would be a really old-school, 20th Century, way to handle the problem of remote sensing and display of shaft position. Here in the 21st Century we have available "new and improved" ways of doing such things, some of which don't even require a shaft or a rotating...
  9. hevans1944

    What type of battery is good for emergency power for blackouts?

    It isn't possible, IMHO, to provide a backup power source that meets your other requirements for that amount of money. OTOH, your short-list of five low-power items does seem to be doable with lead-acid battery technology, specifically the AGM variety in a sealed, no-maintenance, package...
  10. hevans1944

    What type of battery is good for emergency power for blackouts?

    Maybe you just haven't lived long enough yet, despite your common-sense precautions to avoid excitements.:D
  11. hevans1944

    How to create 3D omnidirectional antenna set?

    It is a provable fact that any bare antenna (no in-line receiver amplifiers allowed!) works equally well for transmission as well as reception. When antenna transmit/receive directional patterns are measured or calculated (from an antenna modeling program such as EZNEC) the directional gain is...
  12. hevans1944

    What type of battery is good for emergency power for blackouts?

    I hope you have learned from other posts on this thread that battery power alone is not a good solution for blackout conditions, mainly because you don't know how long the blackout will last. Even the largest battery bank is eventually depleted by an extended blackout condition. After depletion...
  13. hevans1944

    15W Laser Diode

    Somehow I got the impression this was a green laser diode, not that color or wavelength matters much in terms of whether the laser diode is working or not. Why hasn't @jimbod responded to @(*steve*) 's question (posted twice now!) in post #2 and post #9? We can't help without information from...
  14. hevans1944

    15W Laser Diode

    I remember reading this in the 1970s when some of us were involved in "Star Wars" type laser projects. Very sobering. A 15 W green laser is nothing to fool around with, despite not being able to start any fires with it... yet. At the very least, protective goggles are needed that are specific...
  15. hevans1944

    Resistor Question

    I know the feeling. Back in 1967 I was completing a four-year term of enlistment as an Armament and Electronics (A&E) maintenance mechanic with the USAF. The previous year I had studied and passed an exam (code at 5 wpm plus theory multiple-guess exam) to qualify for a Novice Class Amateur Radio...
  16. hevans1944

    Resistor Question

    Just so you know: voltage is defined as the electrical potential measured between two points. So-called voltage drop occurs across particular components in an electrical circuit when the current in the circuit is impeded (or resisted) by components that exhibit resistance (resistors), reactance...
  17. hevans1944

    Normal resistors for High Voltage application

    Um... me knows that. Hard lessons learned over a long period of time, but I kept careful notes. I suspect there are others, too, on this forum who learned the same lessons and just haven't spoken up yet. I am working on a project that hopefully will initiate the newbie on the three major...
  18. hevans1944

    Normal resistors for High Voltage application

    Current doesn't want to do anything. It just is or it isn't, either case being determined by well-known laws of physics. All resistors have a voltage rating whose absolute maximum value is determined by the breakdown resistance of their surrounding environment, usually air, but sometimes a...
  19. hevans1944

    Resistor Question

    Accuracy and resolution (number of digits displayed on digital multimeter) are not necessarily related. My B&K Precision Model 2890A Multidisplay Multimeter displays from 00000 to 49999 before it goes into OL indication on the display, so it has a resolution of one part in about fifty thousand...
  20. hevans1944

    Resistor Question

    I agree that analog meters are more useful in making low-resistance measurements. I love my little Triplett Model 310 pocket-sized multimeters, of which I own two. One has an external clamp-on AC ammeter that attaches to the top of the meter case. The other has the clamp-on fitting but is lacks...
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