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  1. hevans1944

    [HELP] Trying to build very specific portable battery!

    Why don't you buy an AC inverter and try it out? You are gonna need an inverter no matter what "battery" you come up with to power it, so you might as well get that out of the way now. I do think you will be disappointed in the "run time" you get from a pair of 6V lantern batteries. Even the 12...
  2. hevans1944

    New guy from N.C. usa

    You can hang with us... big dogs, small dogs, everything in between... as much as you want! Just remember there are no stupid questions, but you may get some pretty stupid answers. It does help to clearly describe a problem, more so than it does to attempt to describe what you think is a...
  3. hevans1944

    A hard to resist problem

    You can also measure the lead diameter. Smaller wattage resistors usually have smaller lead diameters than larger wattage resistors. And the method of @dorke works too. I use 1/4 watt almost exclusively for solderless breadboarding because 1/2 watt (and higher) resisitor leads either have to be...
  4. hevans1944

    Where to start? - beginner

    Well, I was gonna post something, but my wife interrupted me. I had to hang some plastic over a window in the kitchen that has a largeish air conditioner. The heat-shrinkable plastic mounted with two-sided sticky tape keeps out this winter's cold air. Of course we are betting that there will be...
  5. hevans1944

    Thermo Electric Generator - Variable resistance USB Circuit

    You could connect three of them in series, followed by a switching power supply to regulate the output voltage to five volts for the iPhone. How are you going to heat these puppies up to 60 C? You also need to provide a pretty good sized heat sink to maintain the cold side near ambient...
  6. hevans1944

    How do I load a schematic in the body of my message?

    And ain't that why we all love electronics (and computers)? Small miracles every day!:cool:
  7. hevans1944

    Drive two relays based on input voltage.

    Fly-by-wire or fly-by-mechanical cable: you pays your money and you makes your choices. I think @AnalogKid has an adequate design, but no design is bullet-proof. If simultaneous operation with both relays energized (fault condition) is to be avoided at all costs, then their contacts could be...
  8. hevans1944

    Touch sensor to activate light for set amount of time

    What you can patent or not all depends on your particular patent examiner and what you are claiming to have invented that is different from prior art. If you are denied on your first attempt, you can make changes (usually in your claims) that may satisfy the patent examiner or a different...
  9. hevans1944

    Touch sensor to activate light for set amount of time

    Welcome to the real world where patents don't really help the little guy at all. With a phalanx of well-paid lawyers, large corporations scoop up patents and use them to silence competition or bury technology unfavorable to their current business model. You do have a business model, don't you...
  10. hevans1944

    I need to hire someone for a logic design

    It would be fun to play with. A pin-hole lens is worth exploring. Very large depth of field possible from one of those if you can provide enough illumination. I was amazed when these devices became available for optical mice, and inexpensive too. A similar scheme has been used for years to...
  11. hevans1944

    Looking for flight instruments etc. inexpensively

    Consider replacing electro-mechanical displays such as artificial horizons, altitude, rate-of-climb indicators, air speed indicators, fuel gauges and the like with individual backlit color LCD displays mounted in "look alike" instrument modules. Almost all (if not all) modern aircraft are...
  12. hevans1944

    Touch sensor to activate light for set amount of time

    You could just drill a hole and mount a photo-transistor or photo-diode under it, using ambient light to illuminate it. When the golf ball rolls over the hole it will temporarily block light to the sensor beneath the hole causing a change in sensor output. The amount of change will depend on how...
  13. hevans1944

    Digital Multimeter Problem "-1" !!!

    Expensive lesson in high-voltage piezo-electric spark generation. The User's Manual clearly states: "Never use the meter to measure voltage that might exceed the maximum allowable input value of any function." Good advice for any measuring instrument.
  14. hevans1944

    Simple latching switch for a pcb

    What!? No text-to-speech app on your computer? What would Stephen Hawking say about that?
  15. hevans1944

    7-segment display 3-to-8 decoder logic circuit (please help, thank you)

    I find it interesting that it's been almost a month since the original post, and the OP has apparently fled this scene without comment, probably to get "help" elsewhere. This thread is yet another example of the GIGO principle: Garbage In, Garbage Out. Too bad the OP didn't more clearly define...
  16. hevans1944

    I need to hire someone for a logic design

    Nice try @GPG but I don't think it will work. The focal length of the lens in front of the 15x15 pixel sensor array is very short. The surface to be imaged must line within a plane only 2 to 3 mm away from a reference plane that is only a few millimeters from the base of the device. Assuming you...
  17. hevans1944

    I need to hire someone for a logic design

    Really good comments, Steve! The suggestion about using critical incidence to avoid submersion of parts in saltwater is certainly worth investigating. And modulating the light source, followed by synchronous demodulation, will certainly suppress background interference from ambient radiation...
  18. hevans1944

    Anyone near Indiana?

    Yeah, but try driving to Hawaii, or even Alaska (which is actually possible) from Ft. Wayne. It takes two days to drive non-stop from Dayton to California. Gotta take a boat or a plane to get to Hawaii from California... or from anywhere for that matter. You should visit the Grand Canyon while...
  19. hevans1944

    Anyone near Indiana?

    I live in Dayton, OH, about a two-hour drive to Ft. Wayne under good conditions (no highway construction, no heavy traffic, etc.). What are you going to be doing in Ft. Wayne?
  20. hevans1944

    I need to hire someone for a logic design

    @Madsalts: Well, it seems you are quite serious about the care and feeding of saltwater aquariums. It is a keen observation that migration of the aeration bubbles across the top of the water to the opposite side is a reliable indication of too much DOC content. Who would of thunk it? You might...
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