A little metal project

NEAT !!!!

Extremely cool, Don.

--Winston

Schweet.

Dave

Velly nice!

What do you use for a power supply?

Nicely done!

Paul

That's my next project. 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.

Good job - as per the usual Foreman standard.

It's cheating a bit, but have you seen these?

$15.99 in one-off for the 700mA version and another $1 for the one with dimming.

Looks like it might be a useful idea for making a small camera mount too.

Nice work Don.

Wes

That would probably be a very sensible approach. Can't do that! I have a pretty good collection of stuff in my goodie box, oughtta be able to come up with a "junk box" design.

I have a camera mount like that. The ball on that one is about .875" dia or so. It was made by Stitz of Japan. I'll bet I've had it for

50 years.

On Thu, 07 Jan 2010 12:30:23 -0600, the infamous Don Foreman scrawled the following:

I'll echo that one, too.

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

Very neat little job .

Found this one on alink on Utubeto site regarding a magazine called Make.

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:

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

SNIP SNIP SNIP

Hey you two,

I know there's lots of OT stuff here on RCM, but it's ALMOST ALWAYS in ENGLISH !!! So how about sticking with the common language in this thread!?!?!?

Heh heh heh.

Brian Lawson, Bothwell, Ontario.

ps....actually, I enjoyed going through my catalogues trying to figure out what you were doing!!

I mentioned earlier working for both MEs and EEs. They don't understand each others' secret language and aren't always too happy that I do.

jsw

Well, ya connect the libtard to the neocon via the winger ... nevermind.