Search results

Search Forums New Posts
  1. hevans1944

    Question

    Almost all Third World Countries believe the answer is FETVM. See this page for possible clarification or obfuscation... your choice.
  2. hevans1944

    A lot of old electronics (NiB), and very little knowledge about it.

    Well, of course they have value to someone who needs them. The problem is finding a willing buyer and agreeing on a price. And, yes, there are warehouses stocking (especially) obsolete parts that will sell for ten to a hundred times more than the original selling price. And there are surplus...
  3. hevans1944

    A lot of old electronics (NiB), and very little knowledge about it.

    There is a store here in Dayton that buys stuff like this... by the ton. Then they pay high-school kids to open the mil-spec packaging and bin the parts for retail sale, typically for 10 cents each. The kids do a fair job of sorting and you can sometimes find "bargains" IF you can find what you...
  4. hevans1944

    child safety in cars

    Not "high CO2," but a child breathing generates CO2 and that might be detectable, along with other environmental clues such as respiration, heartbeat, crying, and movement. Surely the problem is not temperature but the idiots who roll up the windows, lock their car, and leave a child unattended...
  5. hevans1944

    A lot of old electronics (NiB), and very little knowledge about it.

    Unpackage everything and place the components in a large zip-lock plastic bag. Take a picture. Offer the lot for bidding on eBay or, if you have enough, offer to sell by the pound as miscellaneous parts. The electronic parts you have shown so far would only be of interest to a hobbyist for...
  6. hevans1944

    optical character reader and scanner

    You provide the scanner and install the software required for optical character recognition. See this Google results page to begin your search. And, yes, some OCR software can scan a page to see if a particular word is on that page.
  7. hevans1944

    optical character reader and scanner

    The OCR concept has been expanded to now include OFR (Optical Facial Recognition) where "key" points and their geometric relationships in facial images are analyzed and compared with previously stored data acquired from scanned images, usually from television cameras, but also retrieved from...
  8. hevans1944

    Passive sign convention

    Except the OP got Question 2 wrong. The answer is 60 watts, as @Ratch said in post #4 and @Sunnysky implied in post #3. As is the 1A current "source" which is absorbing 20 watts, adding to the 40 watts absorbed by the 40 volt "source" to yield 60 watts total absorbed power from the 50 volt and...
  9. hevans1944

    Was, Were, Wasn't and Weren't

    I must have been thinking of this autostereogram image of a shark when I commented on Harald's binary posting... It does take some practice to see the fish.:cool:
  10. hevans1944

    Was, Were, Wasn't and Weren't

    Ummm... it's highly subjective. Most of the time I don't see much of anything, but maybe I need to practice on my squint and staring off into infinity technique.:p
  11. hevans1944

    Was, Were, Wasn't and Weren't

    If you squint your eyes at the above post and stare off into infinity a stereo image will appear.
  12. hevans1944

    Electronics Project

    I will add to Harald's suggestion to use limit switches and actuators to reverse the direction of rotation. The "best" way to do this is with two cams mounted adjacent to each other and attached to one end of your cylinder through a connecting shaft. The cams can be made adjustable by loosening...
  13. hevans1944

    What is this

    A Traveling Wave Tube or TWT is rugged thermionic electron tube device for linearly amplifying microwave RF signals. Various models exist according to center frequency, bandwidth, output power, power gain and noise factor. Closely related to Backward Wave Oscillator (BWO) designs in their...
  14. hevans1944

    We Live In A Wonderful World

    I have waited a long time for someone to invent a procedure to bud new teeth for me. They would also have to re-grow my resorbed bone tissue, which occurs when teeth are removed, but I believe both procedures will be developed in this century. There are many more applications for biological...
  15. hevans1944

    Electronics Project

    We cannot do that until you answer the questions I asked earlier. If you don't know how to calculate (or measure) moment of inertia and the other parameters that I asked about that influence design you will have to muddle through this on your own and try to come up with something that works by...
  16. hevans1944

    Electronics Project

    Depends on what you are trying to DO. How big is the cylinder? What is its moment of inertia? How do you plan to rotate the cylinder? If you are planning to use a motor, will you need to reduce the maximum rpm of the motor to slow down the rotation rate to one revolution per five seconds (12...
  17. hevans1944

    Trying to make a simple LED blinker but it doesn't work...

    You can connect from one to twelve 1.5 V cells (AAA, AA, C, or D) in series to obtain 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, 13.5, 15, 16.5, 18 V DC. This works best with solid tinned copper wire, about 20 AWG or larger, connecting adjacent cells. Arrange the cells side-by-side with their ends...
  18. hevans1944

    Noob needs help with batteries

    An alternator in a car provides all the current needed for everything except the starter motor. As soon as the car is started, the alternator begins to replenish the charge removed from the battery by the starter motor (assuming a successful engine start) while providing additional current at a...
  19. hevans1944

    Hello everybody, thinking of buying this... What are your thoughts.

    Now that I am "retired" even the 55 inch Sony is out of my price range. Just went to the Regal theater at the Fairfield Mall in Beavercreek OH to watch Hillary's America on the "big screen" and was pleasantly surprised to find it was digitally projected in Sony 4K resolution. You could just...
  20. hevans1944

    Peltier

    Interfacing the "cold" side of a Peltier heat pump to a heat-transfer liquid, and then circulating the liquid to the electronics to be cooled is an excellent idea. One way to do this is to seal the "cold" face of the heat pump flush in a hole cut in the wall of an insulated liquid heat-transfer...
Top