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  1. #761
    pole_pig's Avatar
    pole_pig is offline Laser Safety Officer DX Numbers: 1138 Home Channel: 19
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    Hello fellow minion-destroyers. A note about LED lamps replacing light bulbs and saving money.

    Two GE 4000 Hour PAR38 100W halogen flood lamps were replaced with with two CREE brand LED units, PAR38 "120W equivalent".
    One has an advertised 25 degree beam - says SPOT on the box.
    The other has a 40 degree beam, and says "FLOOD".
    These consume 19 Watts each. 1200 Lumens output.
    They are suitable for wet locations, unlike some of the cheaper units.
    Dimmable so the electronic on/off Triac-based controls work with them.
    These cost just under $10 each, plus theft, er.. tax.

    Switching from a 100W halogen flood lamp to a same-function LED pays for the extra lamp cost in saved electricity in 3 months.
    (based on 8 hours a night, 705 total hours)

    The light quality and coverage is at least as good as the old incandescent lamps -as observed.
    The 25 degree unit is better than the Halogen in this job because it is to light a smaller and more distant area.

    Next: sell the lightly used 4000 HR Halogens to someone who can spend only a few dollars.
    Only 630 and 160 Hours on them. hah pretty much like new.

    The burned out 40W light in the outer vestibule was replaced with a 100W equivalent LED 'light bulb' using 16W and making 1500 Lumens.

    Bright Light is a crackhead repellent. No crackheads in the vestibules.

    No idea how much RFI will be coming from these LED bulbs. That might be a problem.

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  3. #762
    pole_pig's Avatar
    pole_pig is offline Laser Safety Officer DX Numbers: 1138 Home Channel: 19
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    The chart shows what can be expected in "Lumens Per Watt" from different lamp technologies.
    In all cases the data is from the manufacturer.

    Note that Watts not converted to visible light are not considered to be converted to Lumens.
    This includes IR, heat, UV and other radiation likely to come from a lighting device meaning a LED, incandescent lamp, arc lamp, etc.

    The Lumen for a given optical power is also directly related to the eye's sensitivity to each wavelength.
    At 555nm, 1 watt is 683 Lumens.
    If there were a perfect lamp radiating equal optical energy from 400-700mn, the Lumen output would be lower at 400 and 700nm and greatest at 555nm where the light-adapted eye is most sensitive. Moving the optical energy output to 507nm with a dark-adapted eye would yield 1700 lumens.

    So.... it's not so straightforward to just do some math, except that manufacturers measure Lumen output of the lamps in a consistent way so that 12oo Lumens from one is 1200 Lumens from the next.

    Anyway we can see that if a 'white' LED lamp makes 95 lumens per Watt, there is still a long way to go to approach the ideal equivalent of 683 lumens per Watt.

    http://hyperphysics.phy-astr.gsu.edu...on/lumpow.html
    http://hyperphysics.phy-astr.gsu.edu...ficacy.html#c1

    Anyway don't worry about all this crap just pick the lamp with a long life and as many Lumens as you want.
    Attached Thumbnails Attached Thumbnails LAMP cfl led COMPARISOn.pdf  
    Electronic Innovations In Action - Setting Energy Traps in the Forbidden Band

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  5. #763
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    The cheap and dirty parametric EQ schematic shown is a circuit for one EQ band with +12 to -12 dB gain range.
    The switch offers one of six center frequencies from 125 to 4000Hz.
    It requires only one dual op-amp. They show a 741 which is OK for communications audio use, but much newer and quieter ones are available these days.

    The point here is that the center frequency is selected by the choice of two capacitors. It is simple to extrapolate from these values for a wide range of center frequencies so that one could build an EQ covering only what is wanted.

    For example, 125Hz = 47000pF + 4700pF, therefore 1250Hz would be 4700pF and 470pF, and 12.5Hz would be 470000pF and 47000pF.

    here so simple simpleton chart: (beware the bandwidth of the EQ channel was not revealed in the article! Nothing's guaranteed!)

    It's clear that they put more emphasis on commonly available values than the precision of the center frequency. The circuit will have other issues at high frequencies trying to control such low values of capacitance on a board and the op-amp input capacitance will have to be checked on the data sheet if changing anything.

    HZ - C2 - C3

    16 - 376,000 - 37,600
    31.25 - 188,000 - 18,000
    62.5 - 94,000 - 9,400

    125 - 47,000 - 4,700
    250 - 22,000 - 2,000
    500 - 12,000 - 1,200
    1000 - 5,600 - 560
    2000 - 2,700 - 270
    4000 - 1,500 - 150

    8000 - 750 - 75
    16000 - 375 - 37.5
    32000 - 187.5 - 18.75


    So all in all it's pretty cheezy where hi-fi is concerned, but for a guitar amp or communications voice frequencies in general is useful. And it's about the cheapest EQ alive.

    Click image for larger version. 

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    Electronic Innovations In Action - Setting Energy Traps in the Forbidden Band

  6. #764
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    The peak reading VU meter circuit is interesting because of the way the gain feedback is done so that the effect of the voltage drop across the diode is reduced to almost nothing. Good example of the technique.

    Click image for larger version. 

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    Electronic Innovations In Action - Setting Energy Traps in the Forbidden Band

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  8. #765
    pole_pig's Avatar
    pole_pig is offline Laser Safety Officer DX Numbers: 1138 Home Channel: 19
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    Electronic Innovations In Action - Setting Energy Traps in the Forbidden Band

  9. #766
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    Electronic Innovations In Action - Setting Energy Traps in the Forbidden Band

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