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  1. hevans1944

    Electronics for prop control

    Here is an update on the Tandetron particle accelerator migration from Dayton, OH to a new home in Anaheim, CA... and also the end of this thread, which I would like to ask a moderator to close. The move ain't gonna happen. It seems I told the principals too much about how the accelerator...
  2. hevans1944

    How to connect wires to prongs on switches?

    After crimping the wires inside the spade terminals, I like to attach them to the switch terminals and then solder both together. If you later need to replace the switch, it's no big deal to unsolder the spade terminal from the switch terminal.
  3. hevans1944

    Super capacitor phone battery

    Well, it is all relative. Electronics in general has become more reliable, and that means the components have become more reliable too. Capacitors seem uncomplicated... two leads attached to two electrodes and a dielectric in between. What could be simpler and more reliable? Well, howsabout a...
  4. hevans1944

    LED setup help needed.

    I think he should learn about ancient reliable technology before it disappears from the surface of the planet. Most of the stepper switches built for telephone exchanges are probably in landfills by now. New ones may not be manufactured to the same standards, and may be somewhat pricey compared...
  5. hevans1944

    LED setup help needed.

    Oh yeah? Without a schematic (a plan of action) just what "stuff" do you think you need to order? Howsabout an 8-deck stepping switch (old-school technology, simple and still available)? Each button push advances the wiper arm one position. Each of the eight "decks" is devoted to one LED. The...
  6. hevans1944

    Huntron Tracker 2000.

    The idea behind the Huntron Tracker is sound: you provide a signal source that is current-limited by intention, then apply it to the device-under-test (DUT), often without removing the DUT from the circuit. Then, on an x-y oscilloscope display (or the equivalent LCD display), the instrument...
  7. hevans1944

    Homemade Coil Help

    Here's a picture of the Model T Ford spark coil, modified for use as a spark-gap transmitter with the addition of the three Fahnestock clips, presumable two for the spark-gap wires and one for the antenna connection. Don't try this at home! Above image copied from this website page. You can...
  8. hevans1944

    Can you identify this part for me ?

    It is more likely that the germicidal lamp or its socket is defective rather than the capacitor. Look for corrosion on the socket contacts, caused by the moist atmosphere inside the towel warmer. You can test the capacitor with some multimeters, but you will probably have to clip or unsolder...
  9. hevans1944

    Vintage Schematic Questions

    If you leave the silicon rectifier diode in place, you are on your own in selecting a resistor. Try @duke37's suggestion to replace the 150Ω with a 470Ω, 5 watt resistor. Measure the power supply voltage, and if it is close to 110 V DC you are good to go. If you still have the selenium rectifier...
  10. hevans1944

    Morse code led without a micro controller

    A lot of it passed us by, too. I don't remember when it happened, but somewhere between now and way back then, technology advanced faster than any single human being could possibly keep abreast of it. We all had to become specialists, knowing more and more about less and less. I fought this, but...
  11. hevans1944

    Homemade Coil Help

    I thought you were gonna dig out an old Ford spark-plug "coil" which used a magnetically-actuated interrupter to rapidly break the current in the primary winding. The rapidly collapsing magnetic field induced a large voltage in the secondary coil. The whole contraption was nicely packaged in a...
  12. hevans1944

    Huntron Tracker 2000.

    There have been several threads here discussing the Huntron Tracker 2000. Visit this page to see what they are. Bottom line is this is not a very useful piece of kit for the 21st Century. Might be fun to play with though. It claimed to be able to test semiconductors, diodes, capacitors, etc. in...
  13. hevans1944

    Making a Thompson's Coil

    The soft iron core is necessary to raise the inductive reactance high enough to prevent overheating of the wire. It also concentrates the induced magnetic field to allow a greater repulsion effect on a single shorted turn (a conductive copper or aluminum ring) placed over the PVC core. You...
  14. hevans1944

    impedance matching required at 20MHz?

    Once RF (radio frequencies) are created and launched into free space by any means, deliberately with an "antenna" or accidentally through inadequate shielding of the generating source, they fall under the jurisdiction of the Federal Communications Commission (FCC). Except for certain "special...
  15. hevans1944

    SOME NEWBIE question about 74ls74 and 74hc74

    Google "74hc vs 74ls" for some informative links. Basically, as @kellys_eye said, they are functionally and logically identical. The 74LSxxx series is low-power Schottky and the 74HSxxx series is high-speed CMOS. The two types can be mixed in the same circuitry ONLY IF you know what you are...
  16. hevans1944

    Morse code led without a micro controller

    Almost exactly my experience with TTL! Almost all of the necessary engineering had already been done by the time I got involved with TTL in the late 1960s into the 1970s. No way I could compete in price or time-to-build with commercial off-the-shelf (COTS) equipment. It had to be a one-of-kind...
  17. hevans1944

    Vintage Schematic Questions

    The company that built and sold this record player was probably either inspired by Muntz TV or it perhaps was Muntz immediate predecessor. Certainly the "design philosophy" is similar: make it as simple as possible with no redundant parts. Read an opinion about this from (deceased) analog guru...
  18. hevans1944

    Super capacitor phone battery

    Possibly. But advances in chemistry can be a lot slower than advances in physics. When I finally realized that a supercapacitor is two high-valued capacitors connected in series, with the connection inaccessible to the outside world, it all made sense. Sure, you only get half the value of each...
  19. hevans1944

    I dont know what is this component in my circuit

    What kind of "school" throws a project like this at a student and then refuses to teach the material necessary for its safe and successful completion? If this is "monkey see, monkey do" type of work, I would quit the course and demand my money back. You obviously have a long way to go, or a long...
  20. hevans1944

    impedance matching required at 20MHz?

    Yes
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