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  1. dave9

    Need a 1.8V supply

    It would be easiest to get a precise output by just using an LDO, low dropout regulator. An old/common choice would be an LM1084. http://www.ti.com/lit/ds/symlink/lm1084.pdf It has a typical minimum load of 5mA and max of 10mA, so if it isn't stable at your 5mA load you might want to put a...
  2. dave9

    Seal acid battery equivalent lithium

    As Bluejets mentioned, I see nothing on that page which takes a mere 8Ah battery. This is beyond what you can power with a single series of 26650 Li-Ion cells so you will need a custom pack of paralleled series and a charger for it as well as either protected cells or a cutoff circuit. It...
  3. dave9

    switch mechanism

    Encapsulate the boat so it looks like a torpedo, which you may need to do anyway for seaworthiness, then no need to disconnect the line, reel the boat in with the fish and you also save battery power not motoring it back to shore (and minimize losing it by keeping the line attached, since the...
  4. dave9

    Seal acid battery equivalent lithium

    A 12V 8Ah sealed lead acid battery is often chosen merely because it is the cheapest cost per capacity and tends to use use a simple/cheap charging circuit. It could be very significant what you're trying to power with it, including needed duration (runtime), and "lithium" is just a chemistry...
  5. dave9

    powering 36 DSLR cameras from a single powersupply

    ^ Putting that in an enclosure will tend to cause it to recirculate the heated exhaust air, so it runs hotter and then should be derated for lower max output, unless your enclosure has a fan added too and/or is partitioned to isolate intake from exhaust. Your PSU is roughly the ideal voltage...
  6. dave9

    Car power to constant current 3.6A 50v boost converter

    Please explain the need for this. I am in favor of DIY, controlling the circuit and making sure it is Done Right. In this case, what are you hoping to achieve? I assume you know you will need a massive heatsink that costs more than some already made light bar from (China?). I assume you know...
  7. dave9

    ATX power supply mod 12v to max V

    Trying to completely reverse engineer a particular PSU and re-engineer it to do what you want (which is what exactly? Trying to make the 12V rail a HIGHER voltage than 12.0V and operate without load on the other rails?) is beyond the scope of a forum topic. I wonder why you feel the need to do...
  8. dave9

    premier message chair php2026

    ^ You are not giving remotely close to enough information because I don't own this chair. If you think the up button is broken based on power going to it but not reversing polarity then it would seem time to replace it. Otherwise, you just take a multimeter and trace all the way through the...
  9. dave9

    For you inventors!

    If the camera is not always streaming the power consumption will be markedly less. If the camera is not a night-time infrared illuminated model it will go down further. You really have to measure it and estimate hours/dary and go from there. Also test for minimum voltage it can use and...
  10. dave9

    Power supply for an in-flight entertainment system

    With all due respect, I get the feeling you are not yet ready to be hooking things up to an airplane's electrical system. :) The first step would be familiarizing yourself with that electrical system so you can answer your own question. Since I don't know anything about avionic electrical, I...
  11. dave9

    How to power one or two of these clusters

    There is no earth point on the COB (not necessarily at least, but the one you linked looks like it has markings for one, you could if you wanted to as you described), but it would be best to earth ground any exposed metal portion of the chassis, especially if the metal it is heatsunk to is...
  12. dave9

    How to power one or two of these clusters

    I haven't built any lights with those integrated COBs, but I do have a cheap work light with one. Unfortunately I haven't ran it for long enough to know if it's going to have good lifespan. It is 12W, and came with a heatsink, but the whole thing got so hot that I upgraded the heatsink. It...
  13. dave9

    Multi Valve Liquid Filling Station

    Yes schottky diodes are readily available at a fair margin above those specs, and no heatsinking needed for 320mA... I'd get something rated for at least 1A current or a little more, probably won't cost but a few pennies more than something rated for 0.5A, mostly swamped by postage. Example...
  14. dave9

    Solenoid drawing barely any current -- is this normal?

    First off, you're powering it with 18V not 24V and second, 9V batteries (assuming the common consumer type) are not capable of much current. While connected, measure what the voltage at the solenoid contacts is. I agree with dave that your meter must be in the wrong range or incapable of...
  15. dave9

    Multi Valve Liquid Filling Station

    Yes, wire the grounds of all solenoid valves together and to the PSU ground. Next run PSU positive to the master switch then through a wire and a diode in series to each of the valves positive contact, a separate wire and series diode for each solenoid. The diode anode facing the PSU side and...
  16. dave9

    Question CRT TV

    You can't make it last forever by just not using it or using it in a special pattern. The capacitors will rot over the decades. Surely you can find an inexpensive used, but much newer, replacement. Here in the US, new larger TV prices (even 4K sets) have plummeted to the point where they also...
  17. dave9

    Edifier X600 speaker circuit burnt components identification

    The resistors are right next to what looks like the audio input jacks, if that is what they are for then it is strange they would suffer heat damage. If they are instead bleeder resistors for the capacitors, having them burn up should not effect the operation of the amp unless that caused a...
  18. dave9

    How to power one or two of these clusters

    ^ Yeah I know the cost is trivial, but say you want something that works more than a few hundred hours, you're investing time and materials (for a housing & heatsinking, soldering PSU wires to two COBs is the least of the time spent to do it right). It could be better to just throw them away...
  19. dave9

    How to power one or two of these clusters

    You may have some trouble getting those to the correct drive current. I have not used this particular product but it looks like many where they did an extremely poor/lazy/cheap job of it, just threw 4 LEDs in series, and paralleled several series of 4. They're thinking that at 12.0V each LED...
  20. dave9

    Solar alarm clock dead(?)

    At 15 y/o it is also due for a new CR2477. I wonder if you can buy the equivalent new for less than the cost of these two batteries... Previously I mentioned putting a AAA NiCd in it. What you could do is put a NiMH in if you want to try to charge it with the solar panel, or put an alkaline...
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