Trike Rider said...
My 2 cents worth. Most high power LED drivers are some version of a switch mode power supply with a low resistance to monitor current and a inductor to control current spikes.
Its odd that you mention this, because while taking a shower I was thinking about the current spike, and thought about mentioning an inductor... I just forgot to post it here...
Hey - great link! I have been playing around with the web bench and it's pretty cool.
The chip it suggests for running 10 rebels in parallel is www.national.com/an/AN/AN-1657.pdf the LM3401. They even provide a circuit that is PWM-able which is pretty cool. I might try to make this circuit during the christmas break and expand it to be RGB based. I just have to run the numbers to see if I can put some programmable aspect to this so I can 'tune' the number of rebels between 1 and 10 for testing.
Now to find a cheap source for rebel RGB stars!
I still think the Mini Mighty RGB +W might be a 'cheaper' solution... (about 45$ assembled for 52x 'straw hat' 8mm 1/2 watt LEDs) www.doityourselfchristmas.com/forums/showthread.php?t=7799
It's interesting to note that project is suffering from LED death. Seems the resistor values were too week to protect the current levels they were trying for with their SSR modules.
The interesting thing about this is it wastes about half the power of the other noted circuit at www.instructables.com/id/Circuits-for-using-High-Power-LED_s/ and has pretty good documentation on how to implement and improve the circuit for catastrophic failures. Plus the addition of PWM in the circuit makes it an easy fit.
2: Several chip vendors are making some interesting products for just the purpose of LED power management. As noted above the National Semiconductors LM3401mm is nice - needing 10 extra discrete components to complete it's circuit. I have found several from ON Semiconductor [url=http:// http://www.onsemi.com/PowerSolutions/parametrics.do?id=197]http://www.onsemi.com/PowerSolutions/parametrics.do?id=197[/url] that are very interesting because the resister is used to set the current level, and not to essentially limit the current which means much smaller wattage resistor is used and the circuits are more efficient. I have yet to get parts to play with this, but wanted to throw these out there to the gang.
Comments
Its odd that you mention this, because while taking a shower I was thinking about the current spike, and thought about mentioning an inductor... I just forgot to post it here...
Hey - great link! I have been playing around with the web bench and it's pretty cool.
The chip it suggests for running 10 rebels in parallel is www.national.com/an/AN/AN-1657.pdf the LM3401. They even provide a circuit that is PWM-able which is pretty cool. I might try to make this circuit during the christmas break and expand it to be RGB based. I just have to run the numbers to see if I can put some programmable aspect to this so I can 'tune' the number of rebels between 1 and 10 for testing.
Now to find a cheap source for rebel RGB stars!
I still think the Mini Mighty RGB +W might be a 'cheaper' solution... (about 45$ assembled for 52x 'straw hat' 8mm 1/2 watt LEDs)
www.doityourselfchristmas.com/forums/showthread.php?t=7799
It's interesting to note that project is suffering from LED death. Seems the resistor values were too week to protect the current levels they were trying for with their SSR modules.
Hey - I liked you 'LED SCHOOL' write-up! Very Forrest Mimms-esque!
Thanks!
I have found 2 things that are interesting for this project so I though I would share.
1: The instructables circuit can get very hot - so heat-sinking is needed. There was a modified version of that circuit that was both more effecient in heat and current useage posted at this site: [url=http:// http://www.e-f-w.com/community/content.php?cid=1026c4f024b494908fc0fecf45679ce3 ] http://www.e-f-w.com/community/content.php?cid=1026c4f024b494908fc0fecf45679ce3 [/url]
The interesting thing about this is it wastes about half the power of the other noted circuit at www.instructables.com/id/Circuits-for-using-High-Power-LED_s/ and has pretty good documentation on how to implement and improve the circuit for catastrophic failures. Plus the addition of PWM in the circuit makes it an easy fit.
2: Several chip vendors are making some interesting products for just the purpose of LED power management. As noted above the National Semiconductors LM3401mm is nice - needing 10 extra discrete components to complete it's circuit. I have found several from ON Semiconductor [url=http:// http://www.onsemi.com/PowerSolutions/parametrics.do?id=197] http://www.onsemi.com/PowerSolutions/parametrics.do?id=197[/url] that are very interesting because the resister is used to set the current level, and not to essentially limit the current which means much smaller wattage resistor is used and the circuits are more efficient. I have yet to get parts to play with this, but wanted to throw these out there to the gang.