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  1. KJ6EAD

    Looking for advice for an LED flag project

    I thought you had already determined the current values you need for the brightness you want with a small quantity of LEDs. If so, those values and the associated average Vfs remain the same. A different supply voltage or number of LEDs in a string only requires using that data to calculate new...
  2. KJ6EAD

    Looking for advice for an LED flag project

    Correct on both counts. You will need to calculate new resistor values but the task should be trivial since you have accurate, experimentally derived current and Vf values. Audioguru is painting a bleak picture of extremes and has not accounted for the lower than typical currents you're running...
  3. KJ6EAD

    Looking for advice for an LED flag project

    I'm pleased to know that you did some testing and brightness tuning but in your effort to have as many LEDs as possible per string, you've gone too far. For good immunity to voltage variation, the resistor portion of each string should comprise approximately 15-20℅ of the voltage drop. For 18V...
  4. KJ6EAD

    Looking for advice for an LED flag project

    The LEDs you've selected are potted in tinted transparent epoxy. Undiffused LEDs are not pleasing to view directly at close range. The red LED has a peak wavelength of 621 nm. That's an almost orange "red". 660 nm is a nice cherry red. Your stars represented with two LEDs and spaced unevenly...
  5. KJ6EAD

    What is this component?

    They reset themselves when they cool down, usually ten minutes or so at room temperature but usually have to be disconnected from power to cool.
  6. KJ6EAD

    What is this component?

    PTC (positive temperature coefficient) thermal fuse and polyester film capacitor.
  7. KJ6EAD

    Led sequence of 10

    You can manually clock an up/down decade counter such as a 4029 or 4192 using a debounced momentary switch and an up/down select switch. You could probably do it with a single 3-position momentary switch but it would require a bit more circuitry to delay the clock pulse until the direction was...
  8. KJ6EAD

    Winter down under time

    A candle flame produces approximately 50W, mostly heat but 2-5% light.
  9. KJ6EAD

    How to access the input and output Gilbarco POS system data path?

    It's proprietary and encrypted but you might use a protocol analyzer to get some insight.
  10. KJ6EAD

    Wanted: Rack Mount Aluminum Chassis

    Whatever you find will be 3.5" tall or slightly less (2 rack units).
  11. KJ6EAD

    A Welcome to EP For AudioGuru

    I'm glad you're here AG. I've been wanting to build a 741/747 based audophile quality headphone amplifier. Where should I start? ;) :rolleyes: :D
  12. KJ6EAD

    Laptop Power Jack

    All of the solder joints in that corner of the board look poor, but that may just be due to flux residue and lead-free solder. In production, high thermal mass devices and ones with a lot of sinking such as metal connectors are barely wetted in the reflow process that's profiled to favor the...
  13. KJ6EAD

    Vintage doorbell issues

    Yes.
  14. KJ6EAD

    AWG?

    I see some copper color in that cut end. Measurement of the insulation diameter is not particularly useful in determining wire gauge but in this case I agree with Tha fios agaibh that it probably isn't critical in this application. You can get a good approximation of the gauge by stripping...
  15. KJ6EAD

    Connecting cable to a pcb pin with electrical tape

    Possible; yes. Reliable; not even slightly. A connector socket crimped on the end of the wire would be much better. A standard or even an improvised wire wrap would also be possible.
  16. KJ6EAD

    What type plug

    Take a lighted magnifier to the wire entry end of the housing. You'll often find some useful markings molded in there.
  17. KJ6EAD

    What to uses as an antenna for rf module

    9⅜" straight, stiff wire will make a ¼ wave dipole for that frequency or you could just buy one. They're readily available for that frequency.
  18. KJ6EAD

    Very slow sewing machine motor operation.

    Only if you stall it a lot. The bigger problem will be the excessive heating in the resistive pedal which will probably lead to the element failing. The obviously most desirable solution would be a different drive ratio but that's complicated by the fact that the motor pulley is usually quite...
  19. KJ6EAD

    Tape Switch

    Ribbon switches are most often custom-configured for original equipment manufacturers. https://www.tapeswitch.com/Switches/Ribbon_Switches.html
  20. KJ6EAD

    Can I Connect a DC-DC step up converter to a USB powerbank?

    You can expect a capacity of approximately 7600mAh.
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