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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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A little metal project
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#2
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A little metal project
NEAT !!!! On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman wrote: http://members.goldengate.net/dforeman/yellowlight/ |
#3
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A little metal project
Don Foreman wrote:
http://members.goldengate.net/dforeman/yellowlight/ Extremely cool, Don. --Winston -- Congratulations Robert Piccinini and Steven A. Burd, WalMart Publicists of the Year! |
#4
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A little metal project
On Jan 6, 11:22*pm, Don Foreman wrote:
http://members.goldengate.net/dforeman/yellowlight/ Schweet. Dave |
#5
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A little metal project
On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman
wrote: http://members.goldengate.net/dforeman/yellowlight/ Velly nice! What do you use for a power supply? |
#6
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A little metal project
On Thu, 07 Jan 2010 10:28:57 -0500, Spehro Pefhany
wrote: On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman wrote: http://members.goldengate.net/dforeman/yellowlight/ Velly nice! What do you use for a power supply? That's my next project. G It needs to be a 700 mA current source with load voltage circa 3 volts or so. Previous version was 350 mA so an LM317 and sense resistor epoxied on the top of a wallwart sufficed. Might work here too if I can find a 4.5 or 6 volt 700mA wallwart. Else, maybe a little switcher. |
#7
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A little metal project
On Thu, 07 Jan 2010 12:30:23 -0600, Don Foreman
wrote: On Thu, 07 Jan 2010 10:28:57 -0500, Spehro Pefhany wrote: On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman wrote: http://members.goldengate.net/dforeman/yellowlight/ Velly nice! What do you use for a power supply? That's my next project. G It needs to be a 700 mA current source with load voltage circa 3 volts or so. Previous version was 350 mA so an LM317 and sense resistor epoxied on the top of a wallwart sufficed. Might work here too if I can find a 4.5 or 6 volt 700mA wallwart. Else, maybe a little switcher. It's cheating a bit, but have you seen these? http://www.leddynamics.com/LuxDrive/...1-BuckPlus.pdf $15.99 in one-off for the 700mA version and another $1 for the one with dimming. |
#8
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A little metal project
On Thu, 07 Jan 2010 14:35:21 -0500, Spehro Pefhany
wrote: On Thu, 07 Jan 2010 12:30:23 -0600, Don Foreman wrote: On Thu, 07 Jan 2010 10:28:57 -0500, Spehro Pefhany wrote: On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman wrote: http://members.goldengate.net/dforeman/yellowlight/ Velly nice! What do you use for a power supply? That's my next project. G It needs to be a 700 mA current source with load voltage circa 3 volts or so. Previous version was 350 mA so an LM317 and sense resistor epoxied on the top of a wallwart sufficed. Might work here too if I can find a 4.5 or 6 volt 700mA wallwart. Else, maybe a little switcher. It's cheating a bit, but have you seen these? http://www.leddynamics.com/LuxDrive/...1-BuckPlus.pdf $15.99 in one-off for the 700mA version and another $1 for the one with dimming. After thinking about that some today, I'm leaning toward a dirt-simple hysteretic switching current regulator comprised of a 220 uH inductor (35 cents at AxMan), MCP6022 opamp, MOSFET, Schottky diode, sense resistor and voltage reference. Maybe 2 more resistors to get a 0.5 volt ref from a 1.23V bandgap device. All bench stock. I sometimes build such simple circuits "in air", no circuit board. Just solder the various parts together with perhaps a bit of hookup wire and then pot the lot in epoxy on top of the wallwart xfmr that supplies the low-voltage line-isolated DC. I need to go to a switcher because of my available xfmr choices. I have several that have the necessary 2.4VA ratings but they're all rated for more voltage and less current than I need. A switcher solves that nicely. Current ripple will probably be about 200 mA P-P, which doesn't matter at all in this app. The biggest inefficiency is in the current sense resistor where maybe a quarter watt becomes heat, oh dear! Uh no, by far the dominant inefficiency and heat generator will be the xfmr. |
#9
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A little metal project
On Fri, 08 Jan 2010 23:45:09 -0600, the renowned Don Foreman
wrote: On Thu, 07 Jan 2010 14:35:21 -0500, Spehro Pefhany wrote: On Thu, 07 Jan 2010 12:30:23 -0600, Don Foreman wrote: On Thu, 07 Jan 2010 10:28:57 -0500, Spehro Pefhany wrote: On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman wrote: http://members.goldengate.net/dforeman/yellowlight/ Velly nice! What do you use for a power supply? That's my next project. G It needs to be a 700 mA current source with load voltage circa 3 volts or so. Previous version was 350 mA so an LM317 and sense resistor epoxied on the top of a wallwart sufficed. Might work here too if I can find a 4.5 or 6 volt 700mA wallwart. Else, maybe a little switcher. It's cheating a bit, but have you seen these? http://www.leddynamics.com/LuxDrive/...1-BuckPlus.pdf $15.99 in one-off for the 700mA version and another $1 for the one with dimming. After thinking about that some today, I'm leaning toward a dirt-simple hysteretic switching current regulator comprised of a 220 uH inductor (35 cents at AxMan), MCP6022 opamp, MOSFET, Schottky diode, sense resistor and voltage reference. Maybe 2 more resistors to get a 0.5 volt ref from a 1.23V bandgap device. All bench stock. I sometimes build such simple circuits "in air", no circuit board. Just solder the various parts together with perhaps a bit of hookup wire and then pot the lot in epoxy on top of the wallwart xfmr that supplies the low-voltage line-isolated DC. I need to go to a switcher because of my available xfmr choices. I have several that have the necessary 2.4VA ratings but they're all rated for more voltage and less current than I need. A switcher solves that nicely. Current ripple will probably be about 200 mA P-P, which doesn't matter at all in this app. The biggest inefficiency is in the current sense resistor where maybe a quarter watt becomes heat, oh dear! Uh no, by far the dominant inefficiency and heat generator will be the xfmr. That should work nicely. The ripple will give you more heating than otherwise, of course. Usual LED mfr recommendations are 5-20% maximum current ripple. Here's another "canned" solution: http://www.sure-electronics.net/DC,I...s/LE-LL209.pdf At the other end of the scale, do you have any of those 5V switchers laying around? Last I looked, a surplus place near me has a big stack of brand new compact 5V wall plug switchers for about $2-3. Inside is a flyback converter using a UC3843 (clone), with the usual TL431 2.5V reference/optoisolator feedback, so changing the resistor ratio on the TL431 would allow the voltage to be lowered to something like 3.5V. (I gently crack the ultrasonic case welding open with a vise, then they can be glued shut again with epoxy- usually you can't tell they were ever opened without looking very closely.). Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#10
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A little metal project
On Fri, 08 Jan 2010 23:45:09 -0600, Don Foreman
wrote: After thinking about that some today, I'm leaning toward a dirt-simple hysteretic switching current regulator comprised of a 220 uH inductor (35 cents at AxMan), MCP6022 opamp, MOSFET, Schottky diode, sense resistor and voltage reference. Maybe 2 more resistors to get a 0.5 volt ref from a 1.23V bandgap device. All bench stock. I sometimes build such simple circuits "in air", no circuit board. Just solder the various parts together with perhaps a bit of hookup wire and then pot the lot in epoxy on top of the wallwart xfmr that supplies the low-voltage line-isolated DC. Where did all those nice unijunction transistors of yesteryear go :-( Mark Rand RTFM |
#11
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A little metal project
On Thu, 07 Jan 2010 12:30:23 -0600, the infamous Don Foreman
scrawled the following: On Thu, 07 Jan 2010 10:28:57 -0500, Spehro Pefhany wrote: On Wed, 06 Jan 2010 22:22:56 -0600, Don Foreman wrote: http://members.goldengate.net/dforeman/yellowlight/ Velly nice! I'll echo that one, too. What do you use for a power supply? That's my next project. G It needs to be a 700 mA current source with load voltage circa 3 volts or so. Previous version was 350 mA so an LM317 and sense resistor epoxied on the top of a wallwart sufficed. Might work here too if I can find a 4.5 or 6 volt 700mA wallwart. Else, maybe a little switcher. Remember to spray paint this one poorly. It'll take the shine off it so it doesn't disappear like the last one. You know how thieves are when it comes to shiny baubles. -- We rightly care about the environment. But our neurotic obsession with carbon betrays an inability to distinguish between pollution and the stuff of life itself. --Bret Stephens, WSJ 1/5/10 |
#12
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A little metal project
On Jan 6, 8:22*pm, Don Foreman wrote:
http://members.goldengate.net/dforeman/yellowlight/ Nicely done! Paul |
#13
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A little metal project
Good job - as per the usual Foreman standard.
Bob Swinney "Don Foreman" wrote in message ... http://members.goldengate.net/dforeman/yellowlight/ |
#14
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A little metal project
On Jan 6, 10:22*pm, Don Foreman wrote:
http://members.goldengate.net/dforeman/yellowlight/ Looks like it might be a useful idea for making a small camera mount too. |
#16
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A little metal project
Don Foreman wrote:
http://members.goldengate.net/dforeman/yellowlight/ Very neat little job . Found this one on alink on Utubeto site regarding a magazine called Make. http://www.flickr.com/photos/lishnes.../in/pool-make/ -- Kevin (Bluey) "I'm not young enough to know everything." |
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