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  1. K

    Identifying input polarity

    The 0 ohms between the negative side of a capacitor near the power inputs and one of the supply wires is a pretty good indication that it's the negative side, but it's hard to know with 100% certainty. Can you post a picture of the PCB? What is the device? I assume you don't have instructions...
  2. K

    Replacing batteries with USB power source

    I'd be surprised if that camera doesn't have a USB port already on it, to download footage if not to power it without the batteries. Or at least a DC barrel jack. Do you have a product name/model number or a link to product info? I googled "infrared camera with 5" screen" and found what...
  3. K

    Replacing batteries with USB power source

    18650 batteries have a nominal voltage of 3.6-3.7V each (a bit higher when fully charged and lower when discharged). 2 in series will be 7.2V or so, while a USB power adapter provides 5V. You'll probably need a boost converter to bump the voltage up from a USB charger. How are the batteries...
  4. K

    Help Identifying a Component

    At that age especially unused it's probably in need of new electrolytic capacitors as well. Being from 1960 you may be able to find a schematic or service manual online. That would help identify the component, its value, and its purpose.
  5. K

    Question hdd badblock interference and dvd burn

    Back in the old days, when you bought a hard drive (usually MFM or RLL type), it would usually have a sticker on it with the locations of bad sectors printed on it, as the drive was tested in the factory. When you low level formatted the drive, you'd enter these locations into the formatting...
  6. K

    Question hdd badblock interference and dvd burn

    Modern drives will reallocate bad sectors (blocks, clusters, etc.) from a pool of spares (when it detects them) and they will appear "good" to the operating system or end user, until it runs out of spare sectors to reallocate. Unless you look at the SMART data, you won't know from Windows (or...
  7. K

    Capacitor id

    185 means 18 followed by 5 zeros in picofarads = 1,800,000 pF = 1.8 μF. K = 10% tolerance. 250V = 250 volts max.
  8. K

    Comedy Thread

    The inventor of USB has passed away. When they buried him, they had to turn the coffin around 3 times to get it into the ground.
  9. K

    tens of years battery life ?

    Most alkalines won't last 20 years left in the package. They usually self discharge and/or leak long before then. If you need something to run that long without external power, could you use rechargeable cells and a solar panel? Even rechargeables don't last forever, but with that light a...
  10. K

    How to replace thermal transformer fuse

    Test continuity between the two ends of the primary coil, and the two ends of the secondary coil, and make sure neither are open. There should be no continuity if you test between primary and secondary. Is the fuse wired to the primary or secondary?
  11. K

    How to replace thermal transformer fuse

    If you can get the fuse body in more or less the same spot as the original, you can leave longer leads on it to solder it and it should be fine.
  12. K

    How to replace thermal transformer fuse

    If it's a regular fuse that blows on overcurrent it can be outside the windings. If it's thermal... that is, it opens if the transformer windings get too hot, it will need to be in contact with the windings to detect this. Have you tested the fuse with a multimeter to confirm it's open?
  13. K

    Battery Consumption

    The trouble with lithium ion batteries like those used in power packs is overdischarge will damage them. If the power bank drains too much while you're gone, the cells can go bad, and they can fail catastrophically when recharged again. There's usually a protection circuit in a power bank to...
  14. K

    Powering car 5000w 500rms amplier and with xbox 360 psu

    What's the voltage of the xbox 360 psu? There are plenty of 12V power supplies readily available for running car electronics at home. Is there a reason you're using a car amp to drive subwoofers in your house? There are AC powered amps for this purpose that work quite well. Also, if it's a...
  15. K

    Wire rating for HID headlight ballast

    What's the wattage of the bulbs and the current draw of the ballast? HIDs put out more light per watt compared to halogen so if you're using the existing halogen wiring it should be adequate. It should say on the ballast, or in the documentation how much current it draws. Note that HIDs...
  16. K

    Variac question

    Leaving the ground on the scope floating is going to give some erratic readings, as you can see. Anyway, this is what I think is happening. If you think of voltage, it's always a difference in potential between 2 points. The + and - terminals of a battery, the live and neutral connections on...
  17. K

    Cat6 and Cat5

    If you're running cables for network inside walls/ceilings, especially in new construction, I'd go with the highest category you can afford, for future proofing. But, to answer your question, CAT6 is fine for CAT5 applications.
  18. K

    Toggle between 2 LEDs on separate circuits in the same circuit?

    That would be ok if only one LED were lit at a time, but when lighting 2 (or 3) at once they will be dimmer than when lighting 1, and the LED with the lower forward voltage may "hog" all the current and prevent the other LED from lighting at all. It's best to give each LED its own resistor...
  19. K

    Can I stack effects

    You can, yes, people connect effects in series often. Usually separate pedals though. For delay, you'd have to use either (a) a tape loop, (b) BBD chip(s), or (c) digital (convert analog to digital, store in RAM, and playback). Probably easier to buy a pre-made delay pedal, or use a software...
  20. K

    Taking Requests

    Last one was Black Dog by Led Zeppelin. Great playing. Though I was hoping for the fast paced opening riff to "Spirit of Radio"... :)
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