evilc66 Posted July 23, 2009 Share Posted July 23, 2009 Power supply arrived today. Don't have the LED yet but before I make it go pop just to reassure my paranoia - can I just connect one (parallel) MCE in series and it will only pull 3.7vf (ish) - i.e the supply will be current limited and the voltage will vary with load and not send 24V to the LED? The driver will adjust accordingly to the voltage required. What is the frequency for PWM dimming anyway? 100hz? 100khz? Couldn't find it in the spec sheet on the frontpage. The frequency is stated a little further down the datasheet, but it's 100Hz-3KHz. The circuit I have built runs at about 300Hz and works fine. Link to comment
keli Posted July 23, 2009 Share Posted July 23, 2009 That should be easy enough. Just use my attiny13v, a transistor and voila, done Link to comment
plankton99 Posted July 24, 2009 Share Posted July 24, 2009 The driver will adjust accordingly to the voltage required. EVIL or anyone else who knows: I just ordered two ELN-60 48D (dimming). You said above the driver will adjust voltage. so lets say i hooked up in series: 8 (CREEXRE-W107, White Cree Q5 XR-E Star) at 3.3vf = 26.4 vf -so are you saying that the ELN-60 48Vold driver would adjust voltage down to 26.4v? then if i hooked up in series 14 (same led as above) at 3.3vf = 46.2 vf - the driver would adjust to 46.2.. and since they are in series, would the total amps still be 1000mA? please help here, a bit confused. I really want to hook up 24 cool whites and 24 royal blues to 2 drivers, how would you recommend i do this with these driver... Link to comment
keli Posted July 24, 2009 Share Posted July 24, 2009 EVIL or anyone else who knows: I just ordered two ELN-60 48D (dimming). You said above the driver will adjust voltage. so lets say i hooked up in series: 8 (CREEXRE-W107, White Cree Q5 XR-E Star) at 3.3vf = 26.4 vf -so are you saying that the ELN-60 48Vold driver would adjust voltage down to 26.4v? then if i hooked up in series 14 (same led as above) at 3.3vf = 46.2 vf - the driver would adjust to 46.2.. and since they are in series, would the total amps still be 1000mA? please help here, a bit confused. I really want to hook up 24 cool whites and 24 royal blues to 2 drivers, how would you recommend i do this with these driver... Yeah it's pretty much as you described. The driver will always provide 1000mA (after you've tuned it down from the default 1300mA), and adjust voltage as needed to provide the constant current, up to max 48v. Works the same in parallel, if you had 2 series of 6 LEDs in parallel (22v-ish), then each of them would be getting half the current it would be getting if it is was just one series. Link to comment
plankton99 Posted July 24, 2009 Share Posted July 24, 2009 Thanks Keli, Very helpful. i also read about a current mirror, so if an LED went out in a string, the other leds in parallel would not get overloaded with current. DO you know about this as well? Link to comment
thelovablebum Posted July 24, 2009 Share Posted July 24, 2009 Was playing with my drivers today, seems the P model can be analog dimmed to a point. What I did was hooked a 9v battery and a external Pot to the dimming circuit. Adjusted the internal Pot to 1000ma when the external is all the way up. With a 10K Pot the LED's will dim down to 210ma and with a 100K Pot they will dim down to 140ma then drop off about half of the pot range. Anybody else try this, have any thoughts on it. Link to comment
evilc66 Posted July 24, 2009 Share Posted July 24, 2009 Thanks Keli, Very helpful. i also read about a current mirror, so if an LED went out in a string, the other leds in parallel would not get overloaded with current. DO you know about this as well? Yes. We have had some disussion on this topic. Was playing with my drivers today, seems the P model can be analog dimmed to a point. What I did was hooked a 9v battery and a external Pot to the dimming circuit. Adjusted the internal Pot to 1000ma when the external is all the way up. With a 10K Pot the LED's will dim down to 210ma and with a 100K Pot they will dim down to 140ma then drop off about half of the pot range. Anybody else try this, have any thoughts on it. I had tried that when I got my "P". I got about the same results that you did. It wasn't very controllable, but it did work to a degree. Maybe it was just my driver. This was the first one that was hand built by Meanwell, so it could have been faulty. Link to comment
McJosh13 Posted July 25, 2009 Share Posted July 25, 2009 Yes. We have had some disussion on this topic. I had tried that when I got my "P". I got about the same results that you did. It wasn't very controllable, but it did work to a degree. Maybe it was just my driver. This was the first one that was hand built by Meanwell, so it could have been faulty. Not just your driver, same results here. Seems dimmable to maybe 50% before it just shuts off by varying voltage Link to comment
evilc66 Posted July 25, 2009 Share Posted July 25, 2009 Ok. My original driver was not working with the pwm cicuit, so it was possible that the analog created problems too. Link to comment
deepdvnarq Posted July 26, 2009 Share Posted July 26, 2009 hey evil, is there is driver, meanwell perhaps, that would drive more LEDs than 13? i'm tying to help out some friends design a big LED array. thanks! Link to comment
evilc66 Posted July 26, 2009 Share Posted July 26, 2009 Drivers like the ELN-60-27 can run a lot of LED, but they have to be in parallel strings. The ELN-60-48 runs the most in series right now. Link to comment
mmike1992 Posted July 26, 2009 Share Posted July 26, 2009 i just got the meanwell p style from the group buy (thanks evil) i am still a little confused is it possible to run this without anything connected to the dimming wires will the leds light at all thanks,mike Link to comment
keli Posted July 26, 2009 Share Posted July 26, 2009 i just got the meanwell p style from the group buy (thanks evil) i am still a little confused is it possible to run this without anything connected to the dimming wires will the leds light at all thanks,mike Nope, I'm pretty sure you need 10v to connect the control lines to get light. Nothing connected means 0% light. (As opposed to the buckpucks where 0% power on control = 100% light, and 100% power on control = 0% light) Link to comment
bxz Posted July 27, 2009 Share Posted July 27, 2009 The P version is not designed to dim using analog input, and I think the color temp will change by analog dimming. PWM will keep the color temp constant while reducing the intensity. Not sure if the D type keeps constant color temp when dimming. Not just your driver, same results here. Seems dimmable to maybe 50% before it just shuts off by varying voltage Link to comment
evilc66 Posted July 27, 2009 Share Posted July 27, 2009 Doesn't work that way. The driver is just interpreting the analog voltage as a duty cycle based on voltage averages. You can't change the color temp of an LED unless you force it to run at certain extreme voltages that aren't safe. This is not capable with a driver like this where the voltage is controlled based on demand. The dimming circuit does not directly control the output like a linear driver would, so the input method will not affect how the output works. Link to comment
bxz Posted July 27, 2009 Share Posted July 27, 2009 thx evil for clarifying. I forgot you can treat the analog input as 100% duty cycle. Maybe that's the reason you won't be able to do 18%-100% dimming (according to the spec). Still surprised at that 50% dimming, 100% duty cycle should give u max output all the time though. I have the latest Arduino PCB, planning to try that on the P. Doesn't work that way. The driver is just interpreting the analog voltage as a duty cycle based on voltage averages. You can't change the color temp of an LED unless you force it to run at certain extreme voltages that aren't safe. This is not capable with a driver like this where the voltage is controlled based on demand. The dimming circuit does not directly control the output like a linear driver would, so the input method will not affect how the output works. Link to comment
Rental Posted July 27, 2009 Share Posted July 27, 2009 Can any electronic gurus explain the example schematics at the end of this doc: http://www.meanwelldirect.co.uk/public/ran...7%5Cr1107_3.pdf In particular why the parallel strings of LEDs seem to be interconnected in a grid layout (does this stop thermal runaway?) and also why one configuration has resistors built inline with the strings (is this to allow for a variable number of strings?). Link to comment
sialkoti Posted July 28, 2009 Share Posted July 28, 2009 thx evil for clarifying. I forgot you can treat the analog input as 100% duty cycle. Maybe that's the reason you won't be able to do 18%-100% dimming (according to the spec). Still surprised at that 50% dimming, 100% duty cycle should give u max output all the time though. I have the latest Arduino PCB, planning to try that on the P. Not too sure how Arduino would do the full dimming since it has 5Volt max ref for dimming and ELN-60-48P are 0-10Volt for full dimming needs. You may only be able to dim your LEDs via Ardunio halfway not 100%. I could be wrong but this is what I been told by a senior member on Ardunio forum. I am sure with few changes it would be possible to run Arduino with ELN-P versions. Link to comment
evilc66 Posted July 28, 2009 Share Posted July 28, 2009 Can any electronic gurus explain the example schematics at the end of this doc:http://www.meanwelldirect.co.uk/public/ran...7%5Cr1107_3.pdf In particular why the parallel strings of LEDs seem to be interconnected in a grid layout (does this stop thermal runaway?) and also why one configuration has resistors built inline with the strings (is this to allow for a variable number of strings?). It's not to prevent thermal runaway, but to prevent additional failure if an LED dies. It only works in strings of three or more, but it helps to equalize the change in load over a greater area instead of a dead LED taking a string out and affecting the remaining strings. It's not foolproof (doesn't work so well when two LEDs die), but it works. Only downside is the massive increase in wiring. Not too sure how Arduino would do the full dimming since it has 5Volt max ref for dimming and ELN-60-48P are 0-10Volt for full dimming needs. You may only be able to dim your LEDs via Ardunio halfway not 100%. I could be wrong but this is what I been told by a senior member on Ardunio forum. I am sure with few changes it would be possible to run Arduino with ELN-P versions. You would need to switch the pwm input with a transistor connected to a 10v source. Link to comment
Rental Posted July 28, 2009 Share Posted July 28, 2009 It's not to prevent thermal runaway, but to prevent additional failure if an LED dies. It only works in strings of three or more, but it helps to equalize the change in load over a greater area instead of a dead LED taking a string out and affecting the remaining strings. It's not foolproof (doesn't work so well when two LEDs die), but it works. Only downside is the massive increase in wiring. Many thanks Evil. Are you able to explain how it does this in a bit more detail? Also, why it has the resistors in the right hand example? Would this be a "safe" way to wire 4 strings of LEDs in parallel off an ELN-60-24 or will a thermal runaway still most likely occur? Link to comment
evilc66 Posted July 28, 2009 Share Posted July 28, 2009 Basically what happens is that if an LED fails open, there is a path around the LED to equalize voltage and current. When running three strings or more, the failure of a single LED can be handled pretty easily. More than one failure can become problematic as the array is trying to compensate too much. I can't see any good reason to use a resistor at the begining of each string unless the forward voltages of each LED were wildly varied and needed something to limit the current. Thermal runaway is a failure event due to poor current regulation, like when you use a current limiting resistor. Link to comment
chazde3 Posted July 28, 2009 Share Posted July 28, 2009 Hey evil any updates on the 556 pwm circuit for dimming these. My array is almost done and could use some dimming. Link to comment
TheStar Posted July 28, 2009 Share Posted July 28, 2009 Hey evil any updates on the 556 pwm circuit for dimming these. My array is almost done and could use some dimming. In my "Where do I begin" LED thread, Evil mentioned it should be done this week. http://www.nano-reef.com/forums/index.php?...t&p=2349003 Link to comment
iMaGin3 Posted July 28, 2009 Share Posted July 28, 2009 Ive lost track on this whole dimming thing since the last time i posted... Please refresh me quickly. 1. The P models that we got through the GB are able to be dimmed by a LM317 circuit? 2. The 556 circuit is a PWM circuit that can also be used to dim the LEDs? 3. The LM317 circuit is adequate enough to dim the P meanwells that we have? On a side note... Im tired of waiting for Digital Aquatics to release the update to use the ALC with the RKL controller. i purchased the ALC months ago thinking it wouldnt be long for the update to be released. Its really annoying that it was promised and the promised date has come and gone. I just called powergate and they said they cant sell to you unless you have a company? Link to comment
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