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2011-09-25 by Tom Biery
Making PCB for the FTDI Vinculum 2 Chip http://youtu.be/qK6DKbzm024 Overview of the Kinsten PCB UV Exposure Box http://youtu.be/j_5iuFjYY5g [Non-text portions of this message have been removed]
2011-09-25 by Chris Kleeschulte
Hey Tom: Thanks for sharing those videos. They are really great. I am current making my own UV exposure unit/box with these instructions: http://www.instructables.com/id/UV-LED-Exposure-Box/ Your post could not have come at a better time since I am covered in saw dust and fresh from my neighbor's basement where I was using his table saw. I am not sure if the led's I got from Ebay (via China) will be any good, but if they are, I plan on donating the unused lot (about 800 leds) to some other person doing the same thing. I bought 1000 LED's but I may only need about 180ish. Again thanks, -- Chris Kleeschulte KK4DYJ [Non-text portions of this message have been removed]
2011-09-26 by Tom Biery
Thanks, if youi like the videos please subscribe to my youtube channel and let me know how the uv leds work out. My exposure is 70 to 100 seconds,. How are you going to seal down on the artwork?
From: Chris Kleeschulte <laconia@...> >To: Homebrew_PCBs@yahoogroups.com >Sent: Sunday, September 25, 2011 7:13 PM >Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV Exposure Box > > > > >Hey Tom: > >Thanks for sharing those videos. They are really great. I am current making >my own UV exposure unit/box with these instructions: > >http://www.instructables.com/id/UV-LED-Exposure-Box/ > >Your post could not have come at a better time since I am covered in saw >dust and fresh from my neighbor's basement where I was using his table saw. >I am not sure if the led's I got from Ebay (via China) will be any good, but >if they are, I plan on donating the unused lot (about 800 leds) to some >other person doing the same thing. I bought 1000 LED's but I may only need >about 180ish. > >Again thanks, > >-- >Chris Kleeschulte >KK4DYJ > >[Non-text portions of this message have been removed] > > > > > [Non-text portions of this message have been removed]
2011-09-26 by Tom Biery
Are you driving the LEDs with a driver chip like a ZXLD1362?
From: Chris Kleeschulte <laconia@...> >To: Homebrew_PCBs@yahoogroups.com >Sent: Sunday, September 25, 2011 7:13 PM >Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV Exposure Box > > > > >Hey Tom: > >Thanks for sharing those videos. They are really great. I am current making >my own UV exposure unit/box with these instructions: > >http://www.instructables.com/id/UV-LED-Exposure-Box/ > >Your post could not have come at a better time since I am covered in saw >dust and fresh from my neighbor's basement where I was using his table saw. >I am not sure if the led's I got from Ebay (via China) will be any good, but >if they are, I plan on donating the unused lot (about 800 leds) to some >other person doing the same thing. I bought 1000 LED's but I may only need >about 180ish. > >Again thanks, > >-- >Chris Kleeschulte >KK4DYJ > >[Non-text portions of this message have been removed] > > > > > [Non-text portions of this message have been removed]
2011-09-26 by Chris Kleeschulte
Tom: Your questions lead to me to believe that I have no idea what I am doing with this UV led exposure box. My design is not using a driver chip..just a 75ohm resistor to drive 3 leds. This circuit will be in parallel with many other ones just like it. Would I need a driver chip? To secure the artwork, I was thinking that the glass plates would "sandwich" the artwork against the glass plates. Would there be a problem with this? On Sun, Sep 25, 2011 at 9:23 PM, Tom Biery <judsquare@...> wrote: > ** > > > Are you driving the LEDs with a driver chip like a ZXLD1362? > > > [Non-text portions of this message have been removed]
2011-09-26 by Tom Biery
Chris, The Glass Plate should work. Not sure if the LEDs you are using need a driver chip if they burn out then you probably need one. The ZXLD1362 for example holds a constant current thru a series of LEDs. Do you have any idea what the exposure time will be can you do a quick test exposing a piece of PCB before its all built. Just some thoughts I am sure that once you get it built you will have allot of fun with it, UV makes a big differeence. Are you going to use it for thru hole components or SMD mostly I do all SMD, If you do SMD you might want to check out my video series on the SMD Toaster Oven. Reflow Toaster Oven PART 2. SMT http://youtu.be/kyphQ1WUIsk Tom
From: Chris Kleeschulte <laconia@...> >To: Homebrew_PCBs@yahoogroups.com >Sent: Monday, September 26, 2011 6:49 AM >Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV Exposure Box > > > > >Tom: > >Your questions lead to me to believe that I have no idea what I am doing >with this UV led exposure box. My design is not using a driver chip..just a >75ohm resistor to drive 3 leds. This circuit will be in parallel with many >other ones just like it. Would I need a driver chip? To secure the artwork, >I was thinking that the glass plates would "sandwich" the artwork against >the glass plates. Would there be a problem with this? > >On Sun, Sep 25, 2011 at 9:23 PM, Tom Biery <judsquare@...> wrote: > >> ** >> >> >> Are you driving the LEDs with a driver chip like a ZXLD1362? >> >> >> > >[Non-text portions of this message have been removed] > > > > > [Non-text portions of this message have been removed]
2011-09-26 by John Dammeyer
The problem is that LEDs are really current driven devices. Go over the current and the LED either degrades quickly or pops due to heat. And that many LEDs in a sealed box will generate heat raising the ambient temperature. The normal choice with just resistors is to design for under the max rating of the LEDs. But the LEDs may very from device to device by as much as a 10th of a volt and as they get warmer that changes too and in the wrong directly. Say each UV light dropped 3.2V at 20 degrees C. If you put 3 in series that's 9.6V. If your supply is 12V then you need to drop 12.0-9.6V= 2.4V. Assuming you want 0.02A current you then need a 120R resistor. If they get warm and their voltage drops to 3.1V then you need 12.0-9.3=2.7V. To hold it at 20mA 135 Ohms. But with 75 Ohm 2.4V/75 = 32mA which may be above the device rating. And if the temperature drops the LED forward voltage to 3.1V the 75R resistor will increase the current to 35mA. That makes things worse and it thermally runs away and pops your LEDs. If the voltage isn't stable but can rise up to 14V then the same problem exists. 14-9.6V is 4.0V divided by 75 Ohms results in 53.3mA through the LEDs. Then you'd need a 200 Ohm resistor to hold the current to 20mA. There are lots of constant current LED driver circuits on the WEB. Or you can buy them premade. A simple version uses the LM317T as a constant current source. Configure it for 20mA and use a higher supply voltage like 36V or so. Then run 10 LEDs in series. I have a circuit that I designed for lighting up the cables on the Lions Gate Bridge in Vancouver. It has 32 LEDs in series and runs off 120VAC and there are 6 of those in each light fixture. Total power consumption is 15W per fixture. See my home page link below. John Dammeyer Automation Artisans Inc. http://www.autoartisans.com Ph. 1 250 544 4950
-----Original Message----- From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Chris Kleeschulte Sent: Monday, September 26, 2011 3:50 AM To: Homebrew_PCBs@yahoogroups.com Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV Exposure Box Tom: Your questions lead to me to believe that I have no idea what I am doing with this UV led exposure box. My design is not using a driver chip..just a 75ohm resistor to drive 3 leds. This circuit will be in parallel with many other ones just like it. Would I need a driver chip? To secure the artwork, I was thinking that the glass plates would "sandwich" the artwork against the glass plates. Would there be a problem with this? On Sun, Sep 25, 2011 at 9:23 PM, Tom Biery <judsquare@... <mailto:judsquare%40yahoo.com> > wrote: > ** > > > Are you driving the LEDs with a driver chip like a ZXLD1362? > > > [Non-text portions of this message have been removed] [Non-text portions of this message have been removed]
2011-09-26 by Chris Kleeschulte
Tom: Do you have any idea what the exposure time will be can you do a quick test > exposing a piece of PCB before its all built. > I am thinking close to 300 seconds, but I have to test on my common board size. > Just some thoughts I am sure that once you get it built you will have allot > of fun with it, UV makes a big differeence. Are you going to use it for > thru hole components or SMD mostly I do all SMD, If you do SMD you might > want to check out my video series on the SMD Toaster Oven. Reflow Toaster > Oven PART > 2. SMT http://youtu.be/kyphQ1WUIsk > > Tom > > I, like you, do mostly SMD parts, but there are always through holes parts that creep into my designs. I am just a hobbyist, so I tend to experiment with whatever I can get my hands on. Your videos are the best and I can always count on your posts to this list to be comprehensive, so thanks! > > From: Chris Kleeschulte <laconia@...> > >To: Homebrew_PCBs@yahoogroups.com > >Sent: Monday, September 26, 2011 6:49 AM > > >Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV > Exposure Box > > > > > > > > > >Tom: > > > >Your questions lead to me to believe that I have no idea what I am doing > >with this UV led exposure box. My design is not using a driver chip..just > a > >75ohm resistor to drive 3 leds. This circuit will be in parallel with many > >other ones just like it. Would I need a driver chip? To secure the > artwork, > >I was thinking that the glass plates would "sandwich" the artwork against > >the glass plates. Would there be a problem with this? > > > >On Sun, Sep 25, 2011 at 9:23 PM, Tom Biery <judsquare@...> wrote: > > > >> ** > >> > >> > >> Are you driving the LEDs with a driver chip like a ZXLD1362? > >> > >> > >> > > > >[Non-text portions of this message have been removed] > > > > > > > > > > > > [Non-text portions of this message have been removed] > > > -- Chris Kleeschulte KK4DYJ [Non-text portions of this message have been removed]
2011-09-26 by Chris Kleeschulte
> > The problem is that LEDs are really current driven devices. Go over the > current and the LED either degrades quickly or pops due to heat. And that > many LEDs in a sealed box will generate heat raising the ambient > temperature. > Good point, I did not consider this at all. Traditionally, people think LED's do not generate much heat at all, but it is still a conductor that has some resistance and has current flowing, therefore heat will be generated. > > The normal choice with just resistors is to design for under the max > rating of the LEDs. But the LEDs may very from device to device by as > much as a 10th of a volt and as they get warmer that changes too and in > the wrong directly. > > Say each UV light dropped 3.2V at 20 degrees C. If you put 3 in series > that's 9.6V. If your supply is 12V then you need to drop 12.0-9.6V= > 2.4V. Assuming you want 0.02A current you then need a 120R resistor. > If they get warm and their voltage drops to 3.1V then you need > 12.0-9.3=2.7V. To hold it at 20mA 135 Ohms. > > But with 75 Ohm 2.4V/75 = 32mA which may be above the device rating. And > if the temperature drops the LED forward voltage to 3.1V the 75R resistor > will increase the current to 35mA. That makes things worse and it > thermally runs away and pops your LEDs. > I am blindly following an Instructable, so that may be my first problem. The blindly following part, not necessarily the Instructable part. I am going to rethink some things based on your notes here (thanks by the way!). I think the box may work for a couple few weeks, but will most likely fail as you suggested. I want a long term UV exposure box with consistent results, so I am going to learn more about this based on what you've taught me here. > > If the voltage isn't stable but can rise up to 14V then the same problem > exists. 14-9.6V is 4.0V divided by 75 Ohms results in 53.3mA through > the LEDs. Then you'd need a 200 Ohm resistor to hold the current to 20mA. > > There are lots of constant current LED driver circuits on the WEB. Or you > can buy them premade. A simple version uses the LM317T as a constant > current source. Configure it for 20mA and use a higher supply voltage > like 36V or so. Then run 10 LEDs in series. > > I have a circuit that I designed for lighting up the cables on the Lions > Gate Bridge in Vancouver. It has 32 LEDs in series and runs off 120VAC > and there are 6 of those in each light fixture. Total power consumption > is 15W per fixture. See my home page link below. > > Again. thanks for the free education. I am going back to spice for a bit to do some work and prove out the design. Basic electronics cannot be overlooked! Chris > John Dammeyer > > Automation Artisans Inc. > http://www.autoartisans.com > Ph. 1 250 544 4950 > > -----Original Message----- > From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] > On Behalf Of Chris Kleeschulte > Sent: Monday, September 26, 2011 3:50 AM > > To: Homebrew_PCBs@yahoogroups.com > Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV > Exposure Box > > Tom: > > Your questions lead to me to believe that I have no idea what I am doing > with this UV led exposure box. My design is not using a driver chip..just > a > 75ohm resistor to drive 3 leds. This circuit will be in parallel with many > other ones just like it. Would I need a driver chip? To secure the > artwork, > I was thinking that the glass plates would "sandwich" the artwork against > the glass plates. Would there be a problem with this? > > On Sun, Sep 25, 2011 at 9:23 PM, Tom Biery <judsquare@... > <mailto:judsquare%40yahoo.com> > wrote: > > > ** > > > > > > Are you driving the LEDs with a driver chip like a ZXLD1362? > > > > > > > > [Non-text portions of this message have been removed] > > [Non-text portions of this message have been removed] > > > -- Chris Kleeschulte KK4DYJ [Non-text portions of this message have been removed]
2011-10-01 by Ben L
What you described with a series of 3 LED's and a Series resistor is OK most likely your problem is too much current so you may need to resize you resistor value. Take your supply voltage (-) the voltage of your LED's (x3) for the voltage drop of 3 LED's then use that voltage to figure your resistor value to limit the current to the rating or lower of your LED. Ben --- In Homebrew_PCBs@yahoogroups.com, Tom Biery <judsquare@...> wrote:
> > Chris, >  > The Glass Plate should work. Not sure if the LEDs you are using need a driver chip if they burn out then you probably need one. The ZXLD1362 for example holds a constant current thru a series of LEDs. Do you have any idea what the exposure time will be can you do a quick test exposing a piece of PCB before its all built. Just some thoughts I am sure that once you get it built you will have allot of fun with it, UV makes a big differeence. Are you going to use it for thru hole components or SMD mostly I do all SMD, If you do SMD you might want to check out my video series on the SMD Toaster Oven.  Reflow Toaster Oven PART > 2. SMT   http://youtu.be/kyphQ1WUIsk >  > Tom > > From: Chris Kleeschulte <laconia@...> > >To: Homebrew_PCBs@yahoogroups.com > >Sent: Monday, September 26, 2011 6:49 AM > >Subject: Re: [Homebrew_PCBs] Two Videos demonstrating the Kinsten UV Exposure Box > > > > > >  > > > >Tom: > > > >Your questions lead to me to believe that I have no idea what I am doing > >with this UV led exposure box. My design is not using a driver chip..just a > >75ohm resistor to drive 3 leds. This circuit will be in parallel with many > >other ones just like it. Would I need a driver chip? To secure the artwork, > >I was thinking that the glass plates would "sandwich" the artwork against > >the glass plates. Would there be a problem with this? > > > >On Sun, Sep 25, 2011 at 9:23 PM, Tom Biery <judsquare@...> wrote: > > > >> ** > >> > >> > >> Are you driving the LEDs with a driver chip like a ZXLD1362? > >> > >> > >> > > > >[Non-text portions of this message have been removed] > > > > > > > > > > > > [Non-text portions of this message have been removed] >