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  1. dave9

    Microphone and camera using same power sounds like crap

    ^ You mean that you used an LM7805 and put a bunch of resistors in series AFTER it? If so, that's not the way to go. I'll tell you a secret many people never mention. You can use an LM7805 for variable or different (than reference 5.0V in this case) like you would an LM317, but when you do...
  2. dave9

    Microphone and camera using same power sounds like crap

    Based on those specs I saw a mic listed the same, claims 100 hours playtime. http://www.takstar.com/en/product/detail-16-79-15-289 This suggests a couple dozen mA current at most. With that in mind, I'd run a linear regulator (LM317 or whatever, with a small uF cap after it) to the mic from...
  3. dave9

    'Deliberate' lifespan of modem/routers?

    I find the lifespan issue particularly affects passively cooled consumer grade networking gear, modems, switches and routers. Modems I have the best luck with, though I usually buy Motorola/Arris which tend to be about the best consumer grade build you can get. Routers and switches on the...
  4. dave9

    Powering a wireless door chime transmitter.

    That will probably not work, at least all the old supplies of this type that I have seen, are unregulated and vary the voltage based on switching taps on the transformer winding. The remote is very low current and an unregulated supply would float too high a voltage set to 12V. It "might" work...
  5. dave9

    Transformer Search

    It has been a long time since I tore apart and repaired a train controller, and the one I did might have even been low end (no idea, had only the one occasion to repair one) but from what I recall it did not have a linear regulator, just the two separate discrete transistor implementation of a...
  6. dave9

    Glowing LED Bulb - How Does Circuit Flow

    ^ Sure. The brand name is "Simply Conserve" and it looks like it shares some construction details with past lights IKEA has sold, except different wattage and LED series/parallel config. Upon looking at the light again, I realize I posted the LED config from a different, 2nd light I was also...
  7. dave9

    Led's headlight issue

    No the sensing circuitry cannot be tiny. It has to have large low ohm resistors so it doesn't overheat, and thick traces to carry the bulb current. While I cannot speak for who does pot theirs, I have never seen any that are potted. I did not mean to suggest cutting the sensing trace where...
  8. dave9

    Led's headlight issue

    Although this is an old topic, the solution that I consider the best was not mentioned and others may happen upon this topic with the same issue, more and more often since more and more vehicles now have bulb out indication. These bulb sensing circuits typically feed the power through low ohm...
  9. dave9

    Transformer Search

    Why do you need a linear regulated supply with a toroidal transformer? Why a transformer that's 24VCT instead of just 12V? I mean you state it's 1A @ 12V you're looking to increase current on? Seems like something a basic 12V SMPS (switch mode power supply) would do well at lower cost, even...
  10. dave9

    Glowing LED Bulb - How Does Circuit Flow

    Well I'll be darned, it's starting to make more sense now. I figured there must be the trapped soul of a tortured ghost inside the bulb, or a little bird on a wheel like on the Flintstones, so in attempting to open it and release the ghost, I discovered that what I claimed was a plastic body...
  11. dave9

    Glowing LED Bulb - How Does Circuit Flow

    I don't understand how there is a capacitive connection between myself and ground, especially when only touching the plastic bulb casing. I'm sitting in a leather chair, on plastic wheels, on carpet, even with my feet off the carpet, touching nothing but the plastic LED bulb. If I touch an...
  12. dave9

    Glowing LED Bulb - How Does Circuit Flow

    I have what I'll call a random LED E26 bulb. It has a driver of unknown design, outputting 52VDC to 2 parallel groups of 8 LEDs in series (dual die LEDs, so really 2 parallel of 16 LED dies in series). It is plugged into a utility light fixture, two conductor wire, hot/neutral on a US 110AC...
  13. dave9

    Converting Double Insulated Light To Faux-Case Grounded

    ^ Yeah there's the thing. It's a cheap light and very slim, no room for much more in it. I have several little DC fans but since this isn't set up with any LVDC output it'd need a power supply too or for me to buy a small AC fan that probably costs as much as the whole light does. if it ever...
  14. dave9

    Converting Double Insulated Light To Faux-Case Grounded

    I went with a simple flat plate 'sink, scrap material at that. I didn't feel there would be a lot of gain cutting fingers or even bending up the ends at 90', might slightly warp the middle anyway which I wanted to stay flat. Not much else to say, I used 10 ga. 6061, a couple mm longer screws...
  15. dave9

    Underdriven 12V LED chips in a 120VAC system

    FastTech, for example the following, they aren't what you'd want for everyday household lighting (tint and CRI aren't the best) but to just get a lot of light cheap w/o dubious generic issues: https://www.fasttech.com/products/0/10004538/2058900-cree-xt-e-450lm-4500-5000k-led-emitter-5-pack...
  16. dave9

    Sony hcd991AV.transformer

    ^ What he said... and you may have some other fault that merely changing the resistors won't solve. There was an acre of space on that PCB so if Sony anticipated them handling enough current to heat up, near to the point of overheat and fail, I doubt they'd have used little 1/2W to 1W...
  17. dave9

    Underdriven 12V LED chips in a 120VAC system

    No, running cool enough you might get reasonable life but why do that? I mean you can get something like 5W Cree LEDs for under $1 each now and they are over twice the brightness per current of the defective generic 10W LEDs. At some point that has to count for something whether it be the...
  18. dave9

    Heated Clothing Potentiometer Help

    There's the thing. 7.4V x 0.7Ah = 5.18Wh. You'd start out around 5W for an hour but without regulation (a loss in itself) drop in power output from there. 5W really isn't much for core heating. The average female at rest produces close to 100W. Moving about or a male especially, inches up...
  19. dave9

    Underdriven 12V LED chips in a 120VAC system

    You wouldn't be able to depend on a datasheet for them. The resistive shorts are random defects, result in excess heat loss which varies per specimen so it's measuring current and Vf for best guess thermal dissipation, or measuring heatsink temperature. The only thing positive about the...
  20. dave9

    Underdriven 12V LED chips in a 120VAC system

    The only thing that makes sense out of that is that you are buying those generic 10W LEDs which are configured as a 3x3 Series Parallel array. They are horrible LEDs, having resistive leaks and meh, I have some lying around and will buy more of something else before I use them. The likely...
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