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Thanks for your reply. You make very good and valid points. I suspect if you cool down the vaseline by keeping it in a refrigereator until the last moment before you use it, it would stay consistent enough to avoid spread. Within a few minutes of spreading it on the board it should be sprayed...
Hi all,
Right so as for dimming and what I can see with my eyes - this is an ultra violet exposure box with 2 sides. 70 leds at the bottom and 70 at the top.
I have not made tests using these leds to see how much power I need when exposing a PCB (I have yet to get them to work first). It...
I believe its similar to the above:
each led drops between 3.2 and 3.4v, and that I have 7 leds in series, they will drop at least 22.4V and and most 23.8V and the LM317 will drop a further 1.25+3v so total voltage across LM317 = 7.6 x 600mA = 4.56W
So for this project, I have split the responsibility of the circuitry in different boards. This specific board which powers the leds receives 30V and 5v PWM.
If I am to drive 2 opto couplers (per board) with 5v pwm then I am not bound to search for mosfets with logic level. I could have the opto...
Whatever the outcome of this thread, I still have to do some changes. With that in mind and whatever I decide to use I was thinking of using opto couplers to protect first and formost my computer while I fiddle around and finalise my software and eventually when some leds breaks down and...
Hi Dana,
Thanks so much for your time. Until tonight I cannot test further however somewhere on the web I found this circuit of someone who did the same thing as I want.
I mentioned earlier that I have 20x circuits like the one I am talking about and I also mentioned that each circuit has 7x leds. Thats a total of 140x 3Watt Leds. If I use a Resistor, I would need 20x resistors @ 21Watts each (700mA x 30v) correct? Doesn't that product a lot of heat? Or should I...
Right I was hoping to have some good news but its not happening - I have 2 identical boards so I swapped the board with the new one to ensure I have 100% brand new components, obviously removing the capacitor and the diode to match my initial test and ..... I had 1 row flicker and the rest...
Hi Dana,
This is very good news to me :) I was trying to understand this. I think your 2mS comes from 1000mS / 490hz = 2.04mS and as your diagram shows from the datasheet the LM317 can stabilise in around 8uS so as my initial experiment showed it can work perfectly.
Tonight I plan to desolder...
Hi, ok so I have regulated 30V power supply which I can fine tune to go up to 33v if I wanted to so really its just a small turn of a pot away from 33v. Now that you mention ripple (or someone else did) I feel like monitoring the output of the power supply to see how clean it is!
As for...
Hi so I am trying to control 3W LEDs that have a voltage drop of 3.2 to 3.6v and a max of 800mA. I am using LM317 to limit the current.
I have 7 leds in series potentially 7x 3.6v = 25.2v
LM317 needs 1.25V + 3V
Total voltage 29.45V hence the 30V input
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