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  1. dave9

    Power Supply for a USB Charger

    No offense intended, but you should just buy a ready made, multi-port USB charger. It's not just a matter of having enough volts and amps, rather modern devices have quick charging tech that benefits from an identification of the charger capability. Plus, it may already have polyfuses, 0-ohm...
  2. dave9

    Tumble Dryer Capacitor

    ?? You pull the connectors off first, then as bluejets stated, connect a high ohm resistor between the contacts. However, this is not really necessary. It's only going to be at line voltage if any voltage is present, not going to arch a significant distance. Simply do not touch the...
  3. dave9

    Dell laptop charger output voltage fluctuates from 16.9 V to 19V

    I'd ask someone in a Dell forum to measure theirs to see if it exhibits the same behavior, if there is not already a topic about it there.
  4. dave9

    Pioneer HTZ 121 DVD power board

    It could help you, to help us, help you, if you sketched out as much of the power board circuit schematic as manageable, because there is a chance someone will recognize the topology of the circuit and what that DIP8 probably did, and potentially suggest a (maybe even drop-in) replacement...
  5. dave9

    Help identifying opposing connector

    ^ What model year is it? Remember that in the internet era, you can search junkyard databases and get things shipped to you too. How about the other idea of picking a mating connector pair and soldering that up? As far as that goes, how about just soldering the wires right onto it then...
  6. dave9

    Help identifying opposing connector

    Pull one off a Volvo at a junkyard? There's likely several Volvo model years using the same connector. Otherwise an auto parts supplier may sell a "pigtail" that is a length of wire with the connector on it. If worst came to worst, you could solder any connector you wanted (that you can find...
  7. dave9

    Battery contact description

    There are many everyday objects you could use there, like a brass nut, copper nail or washer, sawed up pre-1982 (all copper) US penny or for that matter machine them out of any (conductive and solderable) bulk material. For that matter you could probably just use a stainless steel bolt and nut...
  8. dave9

    Higher than rating capacitance

    If there is no name (or brand symbol) on the capacitor, it must be low enough grade junk that nobody wants responsibility for it. Even so, in many applications the exact uF value is not critical, especially when up in the hundreds of uF range where it is unlikely to be used for timing...
  9. dave9

    Help to identify relay pins

    Looking at the datasheet, you should measure approximately 150ohms on the two coil pins with a multimeter. Without powering the coil, you should measure almost zero ohms between the common pin and the normally closed. Powering the coil you should measure infinite resistance between these two...
  10. dave9

    12V to 12V trickle charger help

    Your numbers are a bit off. Engine off, chassis battery should be near 12.6V. Coach battery too for the lead acid, no idea what Li-Ion you have. During vehicle starting, chassis battery will droop momentarily, the few seconds the starter is engaged, then rise to near 14.something volts from...
  11. dave9

    12V to 12V trickle charger help

    Measurements of the voltage of each and the current draw in each state could be useful, but if all you need is to limit current to trickle the chassis system (aka primary starter battery) then a schottky diode and series resistor should accomplish this. Measure the parasitic drain and size the...
  12. dave9

    White noise

    ?? It is one signal with variable frequency, so you can amplify it with a standard audio amplifier circuit you'd use for any other audio playback. What are you trying to do? You can get a white noise audio file and play it on any normal audio player, home or portable stereo or phone or whatever.
  13. dave9

    Min/Max Acceptable Voltage

    Yes acceptable range is listed as 88-265V. Since it reads auto sensing it is likely to just be a switchmode PSU with that wide an input range, not a voltage doubler circuit and switch to that mode. Yes you should be able to use within that range and expect fairly equal performance, with a...
  14. dave9

    Battery question

    Connecting two batteries, or I should write cells, in series like this is done all the time. The negative of one must only contact the positive of the next in series. There are exceptions, mostly dodgy designs, or of course a lead going to a battery monitoring circuit, but mostly it means that...
  15. dave9

    Min/Max Acceptable Voltage

    The internal PSU would be a primary concern, though the UI24R manual has this: AC input voltage range 88-265VAC auto sensing AC frequency 47-63Hz That's probably all the spec you'd get digging further into the PSU in it. You listed the basics but also getting one that's pure sine wave and...
  16. dave9

    change potentiometer threshold

    I'd guess this was an existing product/mechanism and you just need to clean the pot because it doesn't go down to its' former minimum resistance? Maybe also disassemble and bend a slight amount more tension in the wiper and wipe off the conductive track with a dry paper towel then lube with a...
  17. dave9

    Help with capacitor question.

    If you use this link (already has some known parameters chosen), then pick the capacitance, dimensions and any other relevant parameters, you should find a few good replacement options...
  18. dave9

    microsoft surface pro 4 repair

    I don't know what it is, but it looks more like AJX to me.
  19. dave9

    Buzzing in viewsonic VA2407h LED monitor

    It is a little incomplete in that it did not mention that the replacement capacitors typically need to be very low ESR for good lifespan (except the biggest brown one on the right in the picture below). One make and model on Digikey that would qualify and that I've used in the past is Panasonic...
  20. dave9

    need 12v from 56v

    You did not provide your location, important for purchasing products (sometimes) ! I went on ebay and searched "Buck regulator 10A". 10A to give a little current margin over the 6.67A spec you provided, which itself might be conservative, but then again you can decide for yourself if you want...
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