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Thread: Bright LED replacement suggestion?

  1. #1
    Junior Member PeterPan's Avatar
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    Bright LED replacement suggestion?

    I use a Digitech Jamman in my gigs. Its been heavily modified a half dozen times already so this will not be a big deal for me. My current problem is the indicator LEDs, one red and one amber, that serves to comfirm when you are in record mode and overdub mode respectively. As I recall from my last venture inside the unit, these LEDs are pretty much SMT devices, and their light is brought to the front panel via a light pipe variation. As I've seen playing out in daylight, this has to go. I need to be absolutely sure which mode the device is in, including ordinary playback (neither LED on), and too often you just can't see them in the daylight. I've tried surrounding them with 1/4" pieces of small opaque tubing, to shield the ambient light. But then if I happen to be looking at a slight angle, I might not see the indication correctly. So bottom line, what I need is to pick out some very bright LEDs and mount them directly to the surface. If the electronics driving the existing LEDs can't supply enough current, I can easily build a small buffer circuit with a transistor or driver IC. But obviously I want maximum effectiveness with minimal work. Can anyone suggest some VERY bright LEDs for me, that are still small enough to mount somewhere within the pedal? Its so important that i clearly see the mode, I've honestly thought of a separate box with some of those automotive side-markers. That would be a lot of extra work, as I'd need to pull 12VDC from an external supply for my driver circuit. I'm hoping someone can suggest a happy medium, with LEDs they know from actual experience are adequately visible in normal daylight. I don't expect anything short of a traffic light signal to be perfectly visible in full sunlight, but at least full shaded daylight. :-)

  2. #2
    Old Timer tedmich's Avatar
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    I think you could use a logic level N channel mosfet which is actuated by the SMD LED pads to power on some big LED like this
    bildr High-Power Control: Arduino + N-Channel MOSFET
    of course you'd need another DC power supply to feed a big LED like this one
    350 Lumen 10 Watt Super Bright, Red LED | MPJA.COM
    and you would probably want to add a PWM circuit to allow you to not be blinded indoors
    Motor Speed Control, DC 6-28V, 2A with Memory | MPJA.COM
    this one has a memory function that might be handy, or get a smaller knob-set one.

  3. #3
    Junior Member PeterPan's Avatar
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    Quote Originally Posted by tedmich View Post
    I think you could use a logic level N channel mosfet which is actuated by the SMD LED pads to power on some big LED like this
    bildr High-Power Control: Arduino + N-Channel MOSFET
    of course you'd need another DC power supply to feed a big LED like this one
    350 Lumen 10 Watt Super Bright, Red LED | MPJA.COM
    and you would probably want to add a PWM circuit to allow you to not be blinded indoors
    Motor Speed Control, DC 6-28V, 2A with Memory | MPJA.COM
    this one has a memory function that might be handy, or get a smaller knob-set one.
    Ha! (not be blinded indoors)--- LOL. Hadn't thought of that problem. :-) Well I think I'm pretty well versed on how to do any needed driver electronics. I'll look at that LED you mentioned. But before I jump to something that will likely require its own 2 amp switching supply/adapter, I'm hoping to hear from a few that have solved the problem I'm facing without going to more of an extreme than necessary. Maybe there's a 40 or 50mA LED that adequately will solve my issue, and might even be able to be powered by the pedals existing supply. I don't know.

    Thanks for the references though!

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    A few things:

    1) LEDs are rated in terms of millicandles and lumens. You can sift through the listings of distributors and pick a super-duper bright one (>10,000mcd).
    2) Human vision detects some colours more readily than others. It's functionally equivalent to the Fletcher-Munson equal-loudness curve, except for the retina. Pick colours that your eye is most sensitive to.
    3) Visibility of status LEDs on pedals is partly a function of contrast against the background, in addition to pure brightness. The same LED against a black bezel or chassis will be more readily visible than against a light-coloured chassis. For that matter, if you're not averse to modding, consider moving the status LEDs to a separate black plastic chassis, where the contrast is better, and you can even have your choice of size and shape of LED, like green triangular for play, red square for stop, etc.
    J M Fahey likes this.

  5. #5
    Supporting Member Jazz P Bass's Avatar
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    Senior Member Enzo's Avatar
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    You want to make extra circuitry? Make the LEDs blink, that will be more eye-catching than a steady glow.
    Education is what you're left with after you have forgotten what you have learned.

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    Supporting Member eschertron's Avatar
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    Quote Originally Posted by Enzo View Post
    You want to make extra circuitry? Make the LEDs blink, that will be more eye-catching than a steady glow.
    Right. Anything to enhance the contrast is a plus.
    Quote Originally Posted by Steve Conner View Post
    If it still won't get loud enough, it's probably broken.

  8. #8
    Junior Member PeterPan's Avatar
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    Quote Originally Posted by Mark Hammer View Post
    A few things:

    1) LEDs are rated in terms of millicandles and lumens. You can sift through the listings of distributors and pick a super-duper bright one (>10,000mcd).
    2) Human vision detects some colours more readily than others. It's functionally equivalent to the Fletcher-Munson equal-loudness curve, except for the retina. Pick colours that your eye is most sensitive to.
    3) Visibility of status LEDs on pedals is partly a function of contrast against the background, in addition to pure brightness. The same LED against a black bezel or chassis will be more readily visible than against a light-coloured chassis. For that matter, if you're not averse to modding, consider moving the status LEDs to a separate black plastic chassis, where the contrast is better, and you can even have your choice of size and shape of LED, like green triangular for play, red square for stop, etc.

    I guess the problem is I've never had to get a "feel" "mcd" before. At least not the way I've grown to understand the difference between 10mA and 10 amps. One thing I'm noticing is that you can get a 10,000 mcd LED, that has an obvious "water clear" lens, and is specified to only a 20% viewing angle. A similar LED by the same company, same color in the same "super bright" category that has an obvious diffused lens, will typically have 1/10 the "mcd" at the same current.

    I guess I'm just going to have to do some buying and trying, because the numbers don't mean much to me. I don't know, for example, what the "mcd" output of the existing indicators are. AND, I don't know if lumens are perceived logarithmically, as we perceive sound, or more linear.

  9. #9
    Junior Member PeterPan's Avatar
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    Quote Originally Posted by Jazz P Bass View Post
    Thats what's there now. Its output is brought up to the surface with a light pipe. Its way too dim.

  10. #10
    Junior Member PeterPan's Avatar
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    I did consider that, but in this case, these LEDS actually DO blink to warn the user of a certain condition. I've seen some light truck side markers on ebay pretty cheap in red and amber. I'd have to put them in a separate box with their own supply, but no way in hell I'd miss that! :-)

  11. #11
    Old Timer Tom Phillips's Avatar
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    Quote Originally Posted by PeterPan View Post
    Thats what's there now. Its output is brought up to the surface with a light pipe. Its way too dim.
    As you said, you don't have the brightness "calibrated" so you will need to try some things. How bright do the existing LEDs appear if you look directly at them without the light pipe? Maybe the solution will be as simple as running wires to a suitable panel mounted LED.

  12. #12
    Supporting Member eschertron's Avatar
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    Is the 'brightness multiplier' something you need often? The majority of the time?
    Would it be ergonomic to clamp/fasten detectors over the LED display and then run an auxiliary unit that presents the signals, like the truck lamps you mentioned? Sure, it would require a separate power source, but if it were only optically coupled to the JamMan, you would only need to cart it around and set it up on those occasions when needed. Is that an idea worth considering?
    Quote Originally Posted by Steve Conner View Post
    If it still won't get loud enough, it's probably broken.

  13. #13
    Junior Member PeterPan's Avatar
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    Quote Originally Posted by eschertron View Post
    Is the 'brightness multiplier' something you need often? The majority of the time?
    Would it be ergonomic to clamp/fasten detectors over the LED display and then run an auxiliary unit that presents the signals, like the truck lamps you mentioned? Sure, it would require a separate power source, but if it were only optically coupled to the JamMan, you would only need to cart it around and set it up on those occasions when needed. Is that an idea worth considering?
    Thanks. I actually did think about that. I think Murphy's law tells me I'd better not. Bad enough there's already a ton of equipment to set up at a performance, and just my luck I either won't take the ambient light totally into account, or will end up with a "leaky" light coupling. I just wouldn't trust it. I think if I do go external to have a stronger indicator, I'll do it electrically, and add a jack to the main unit where I could tap and bring out the control voltage. Nothing is really NASA fail safe on a musicians budget, but I think something like that would be more reliable.

    I've gotten some decent leads from tech reps at Kingbright and also Broadcom, and some samples are on the way. If any of the parts impress me and work out to be a good solution, I'll post what I found. Wish me luck!
    g1 and eschertron like this.

  14. #14
    Junior Member PeterPan's Avatar
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    So I thought I'd offer a follow up for anyone dealing with something similar. After searching several alternatives, I found some LEDs by Kingbright that seemed promising, requested some samples, and am pleased with the results. The KINGBRIGHT parts I used were RED, GREEN and YELLOW LEDs and their data sheets are available at these links.

    Kingbright USA, an opto-electronic LED manufacturer products include all type of LED LAMPS , SMT LED, SMD LED, LED DISPLAYS optoelectronic components
    Kingbright USA, an opto-electronic LED manufacturer products include all type of LED LAMPS , SMT LED, SMD LED, LED DISPLAYS optoelectronic components
    Kingbright USA, an opto-electronic LED manufacturer products include all type of LED LAMPS , SMT LED, SMD LED, LED DISPLAYS optoelectronic components

    So these are LEDs that only require the usual 20mA. They are only rated about 600 for luminous intensity, but have a few things going for them. First of all, for water clear (not diffused) lenses, they are unique in that that have a pretty wide (30 degree) visibility rating. You can find LEDs with luminous intensity ratings 10X higher, but the visibility may be much more narrow (10-15 degrees). In any case, I took apart my Jamman for about the millionth time, and carefully de-soldered the least critical LED, which was the PLAY LED. Its not critical because if it is on, there is sound playing back out of the looper, so its indication wouldn't be missed much if I destroyed to original SMD LED. Looking at the schematic for this looper, I could see there were already adequate series resistors in series with the original LEDs, but a check with a scope proved these LEDs were not on "steady state", but were being pulsed (likely multiplexed). So I decided to just try a direct replacement. I figured if it still wasn't bright enough, I could always tap the signals and bring them out to my own driver. But I didn't have to! Even though they were not as bright as they would have been with a simple dropping resitor connected directly to a 5V source, the green LED was sufficiently bright that it was a little hard to look at! So I went and replaced the RED and YELLOW indicators, which were the more critical RECORD and OVERDUB indications. I scrapped the original light piped, though they were a handy guide to approximating the lengths needed for the new LEDs to stand of the PC board, and I also had to drill out the small square openings in the case which the former light pipes used, to accommodate the new 5mm wide LEDs.

    The bottom line is, this seems a success! Though I have not yet tried viewing in direct sunlight (never intended really), I can see that the brightness of these indicators is now almost painful to look at, even in a well lit room. I have no doubt that in any reasonable outdoor condition, I will see these indications without fail.
    Tom Phillips, g1 and eschertron like this.

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