Recent content by JohnR66

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  1. JohnR66

    Blackout lighting

    I'd avoid that SuperbrightLED stuff. For $1 more you can get Cree CXA1304 series LEDs at 50 times the brightness and easy to integrate into a 12v system. That gets your lumens per dollar spent ratio much higher! You can select the color temperature you'd like. You will have to mount them on a...
  2. JohnR66

    Why do some CFL bulbs have bulges on their spirals?

    The cfl must keep a reasonably even light output over a wide temp range after warmup. The cold chambers aid in that by keeping the mercury pressure near constant. Plenty of documentation on that. SOX sodium lamp is another example with cold chambers along the tube.
  3. JohnR66

    "Simple?" LED project

    Welcome to CPF! Do the candles flicker or are they steady? The ones that flicker have a little micro controller encapsulated right in the epoxy of the LED and this will not allow them to be used as you wish. You can replace the LED with a standard amber one which would allow you to parallel...
  4. JohnR66

    What happens if I exceed max forward current?

    That red LED on Super Bright LEDs is poor. Intensity is relatively low at the tight beam angle of 8 Deg. Cree's C503B series red LEDs can hit over 20,000 mcd at only 20ma and a beam angle of 15 Deg so it is making many times the light of the LED in your link. They can run at 50ma as well. For...
  5. JohnR66

    LED Compilation List

    Welcome aboard! You just have to hang out and read/join the discussions. LEDs are in constant flux (pardon the pun). They are improved and new products released very often making lists challenging to keep up to date. There are discussions about many of the new LEDs and flashlight reviews here on...
  6. JohnR66

    Lumen maintenance for PC or PMMA lens

    More information of the light's intended use would be helpful. Acrylic is the better choice of the two as it will not yellow or haze from the light energy over that span of time. PC, as used in car headlamp covers, tend to yellow and haze from UV light and weathering, however, there may be...
  7. JohnR66

    Radio Shack white LED

    Now this is an old thread! In Oct 2009 I connected the RS 276-017 at continuous drive at 30ma to perform my so called fade test as I found nearly every single cheapo Chinese LED would fade in less than one week's time (yes these are still just as crappy today). The RS LED is still connected and...
  8. JohnR66

    Polaroid BR30 800 lumen bulb under $10

    I don't see them on Polaroids site. Must be very new. What is the power draw indicated on the packaging?
  9. JohnR66

    Was your neighborhood ruined by new LED streetlamps?

    Heck, my neighborhood still has mercury vapor streetlights. At least they use the DX white (phosphor coated) bulbs that add red to white light so people don't look like walking cadavers.
  10. JohnR66

    Stupid question but what will happen if I switch on a CFL bulb that has a hole in it?

    The filaments at the tube ends will attempt to light and probably burn out since there is air in the tube and no arc (technically more of a low pressure discharge than an arc) can be struck. The CFL ballast circuit is a simple push-pull oscillator/driver that depends on the electrical load of...
  11. JohnR66

    Why do some CFL bulbs have bulges on their spirals?

    I've seen them in a 4 watt CFL. Most are right at the top of the bulb where the glass swells a bit.
  12. JohnR66

    Why do some CFL bulbs have bulges on their spirals?

    The little bumps you see in the glass tubing actually have a purpose. They are cold chambers to help regulate the mercury pressure within the tube when it is in operation. You can read more about it here: http://www.google.com/patents/US7759850 Modern fluorescent lamps actually contain little...
  13. JohnR66

    new(?) Sylvania LED bulbs

    I found the bulbs to run quite hot. 80 Deg C on the metal heatsink area between the base and globe. I measured this with a thermocouple and a dab of thermal grease. Measured base down in an ordinary table lamp. Modern LEDs of good quality can handle this (Cree CXA1304 LEDs will take 105C case...
  14. JohnR66

    Polaroid BR30 800 lumen bulb under $10

    I've seen the two pack as well but it was for the 650L version.
  15. JohnR66

    new(?) Sylvania LED bulbs

    I picked up three of these bulbs (800L version). Light distribution (by eye) is excellent. It uses a pentagon aluminum tower with the PCB folded down over it and adhered. 24 smd LEDs in all. Bulb dims down well with minimal buzz. Power draw at 122v is 8.8 watts and PF of .93. The white area...
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