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  1. hevans1944

    Capacitor test box

    They are commonly called capacitor substitution boxes. Some offer decade selections, others do not.
  2. hevans1944

    Capacitor test box

    Google is your friend here.
  3. hevans1944

    Help! College Project

    Welcome to Electronics Point, Frank! Why not just engrave the Braille representation of each coin denomination vertically on the side of the bottom cylinder, and allow the user to manually align the semi-circular slot in the top disk by simply rotating the top disk by hand? No motor required...
  4. hevans1944

    I Need Some Help With a Level Indicator Project

    I am no expert on front-end loaders (or whatever this tracked beastie is), but I believe you rotate left or right by applying differential-drive to the tracks, like an army tank does. It probably requires a good bit of finesse to turn and move forward/backward at the same time..
  5. hevans1944

    I cant step up voltage

    Why are you using a DC motor to turn a "generator"? What do you hope to accomplish
  6. hevans1944

    Controll for Seven-Segment-Displays

    @dorke : At least the OP lives in Germany, where such things are available.
  7. hevans1944

    Help with programming an EEPROM

    With only 1000 different BCD numbers from 000 to 999, clearly you don't need to use every one of the 32,768 locations available in the EEPROM. So just connect the BCD bits to the first twelve address bits, A0 through A11, and program those locations with the binary equivalents of the three...
  8. hevans1944

    An unidentified component

    With four leads it is probably a ferrite-core transformer. Good luck trying to find another one exactly like it. Are you sure it is bad? Make continuity tests on all possible combinations of leads, measuring two at a time: 1&2, 1&3, 1&4, 2&3, 2&4, and 3&4. There should be continuity on two of...
  9. hevans1944

    Basic appliance question

    Power varies as the square of the voltage for a given resistance. So if you plug in 220 V AC appliance on a circuit that only provides 110 V AC, you only get one fourth the power at half of the rated voltage. Appliances that draw small currents, such as phone chargers and laptops, often have...
  10. hevans1944

    Controll for Seven-Segment-Displays

    You might look here to purchase in Germany.
  11. hevans1944

    Help identifying component.

    Neon lamps need something (usually a resistor) to limit the current after they begin to conduct:
  12. hevans1944

    Controll for Seven-Segment-Displays

    Sorry, I don't see any circuit included in post #7. And I missed the internal circuit for the two-digit 7SD you included in post #9. And, yes, multiplexing is the correct term. You have to multiplex the two digits because, for either of the two digits, any given segment on one digit shares a...
  13. hevans1944

    Controll for Seven-Segment-Displays

    @Ch33f: Why would you think the internals of the MAX7221 bear any resemblance to either your "Bad" of "Good" sketches? They don't. The Functional Diagram that @dorke included with post #8 is just that: functional. It does not in any way represent the actual internal circuitry, except to show the...
  14. hevans1944

    An Electronic Symbol

    It indicates there is more circuitry, such as a motor load, that is not shown on the schematic.
  15. hevans1944

    LED strips not lighting up

    It is highly unlikely that there is anything wrong with your LED strip. The connection of the LED strip to the power supply cable, the one covered with shrink tubing, is probably the culprit. Use a single-edge razor blade to carefully cut the shrink tubing off so you can inspect the soldered...
  16. hevans1944

    File types?

    I see from your "test" post that you have figured this out.
  17. hevans1944

    clever vibration motor driver?

    Cardboard is a "tried and true" method of prototyping. The real adventurous omit the cardboard and just leave all the soldered together components hanging in air. Bob Pease was known for this (see image below), and some hams actually prefer it for VHF/UHF projects. Either way, you don't have to...
  18. hevans1944

    Controll for Seven-Segment-Displays

    Just because you have obsolete components doesn't mean you can't have fun playing with them. Just don't plan on building more than one of anything, and hope you never need replacement parts.
  19. hevans1944

    help finding specs on large stud mount rectifier

    What you have may be like this one offered on Ebay for an obscene amount of money. Normally rectifiers like these have the cathode connected to the stud, but yours appears to have the anode connected to the stud. That may be the significance of the "R" in the part number. They generally have...
  20. hevans1944

    Better understanding of Electricity.

    Yeah, just what we need... dumb down the math and forget the algebra. This is how you teach kids to diagnose and troubleshoot problems? This is critical thinking?
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