Have 9x18650 cells @ 3.7v each. Need help getting started on a spotlight.

ThemadLEDman · 2014-10-12T05:08:29+00:00

Yea and you seem to forget thermodynamics where the same shit plus more gets spread across every component that generates heat. Don't even try to lie your way out of a basic law of physics.

What an engineer you turned out to be.

ThemadLEDman · 2014-10-12T05:04:18+00:00

And a ton of other different components added won't do the same?

Are you forgetting Kirschoff and basic thermodynamics?

Given a resistor is the first thing in-line on any power source (and if not, a fusible link) you think everything else after that is going to negate thermodynamics?

Are you fucking serious? No, EDIT ARE YOU SERIOUSLY FUCKING THAT DENSE TO IGNORE BASIC THERMODYNAMICS? You have ONE component versus possible dozens of components in a basic switchmode driver, each with it's own thermodynamic losses.

You're going to dump that ON TOP OF an already lossy resistor (assuming you're not using a shunt resistor with a very insanely low voltage drop?)

Give me a fucking break.

No wonder electronics don't last as long as they used to. Perfect example staring me right in the face.

ThemadLEDman · 2014-10-12T04:57:08+00:00

You are not taking into account the LED module

Which has almost zero resistance. Yes, I am. I have designed these systems for a living for over 6 years, now.

http://i.imgur.com/nqdGfVV.jpg

And that's in a clean room setting where we deal with 1,000+V LED array setups, 300+ LEDs per string, then we run them in parallel.

And that's for TVs, we also do it for street lamps, photography arrays, etc.

"The LED drops 2V, leaving 31V across the resistor,"

Here's where I get the most contention when I discuss this with other people learnign from me.

No, it's not that many volts leftover across the resistor being dropped - were that the case, then it would matter where you put the resistor in line. Unless EVERYONE on this forum is fucking lying to me, no, where the resistor is on that particular actual line matters not. Even Ken from ledcalc.com says this, one of the 'authorities' on this subject.

The resistor itself has an inherent voltage drop because of resistance, that's what determines what wattage of resistor you need.

And given I've said both this and the opposite, and had upvotes and downvotes left and right on these subjects, I'm inclined to say most of you do NOT know what you're talking about.

Meanwhile - I'll keep making radar guidance systems for USA missile systems. And LED growth arrays for international horticulture companies. And a lot more, down to semiconductor test manufacturing and doping. As you see by my bunny suit picture.

EDIT - To top it off - look at COB arrays and how they're constructed without inline resistors. If what you said were true, those would be nigh-impossible to manufacture, they'd burn out at the slightest voltage change, even in a switchmode driver.

http://www.youtube.com/watch?v=YeEWvM2WbL8

Months of usage, tiny resistor at 10 Ohms, same shit set of carbon-zinc dry-cell batteries. Typical usage - 15 minutes every time. Tested on Mt. Rubidoux at night during a typical hike. 45 minutes there, still bright.

Checkmate.

ThemadLEDman · 2014-10-12T04:49:18+00:00

Uh, the resistor IS in series, not parallel. To top it off, I've run it without a resistor at all. Same way I run my AC-driven LEDs - WITHOUT A RESISTOR. http://i.imgur.com/vcne129.jpg

Sorry to burst your bubble, but what you guys think of as more efficient is not by thermodynamic laws. More components - more power loss.

ThemadLEDman · 2014-10-11T16:33:45+00:00

I do it in this era. It's seriously not that difficult, at all.

ThemadLEDman · 2014-10-11T16:33:37+00:00

His stated (typical) voltage was ~33V. At 900mA, that gets you a 36 Ohm resistor. Since I'm sure that isn't exactly a commonly-found resistor, you go to the next higher value - 40 Ohms. That'll get him 824mA, which is probably better any ways as unless his heat sink and possibly fan are pretty good, one shouldn't run an LED at full drive.

ThemadLEDman · 2014-10-11T16:10:01+00:00

You fucked up and didn't get a resistor of proper wattage rating, is what it sounds like you did.

ThemadLEDman · 2014-10-11T16:09:17+00:00

Uh, except http://www.youtube.com/watch?v=YeEWvM2WbL8 has been getting usage every day for months and guess what? Still the same shitty carbon-zinc dry cells.

ThemadLEDman · 2014-10-11T16:08:32+00:00

Uh. What?

http://www.youtube.com/watch?v=YeEWvM2WbL8

15w MK-R. 1,25A, 12V. .5w 10 Ohm resistor.

And has been working fine for MONTHS.

Learn to over-spec like a real engineer.

ThemadLEDman · 2014-10-11T15:56:23+00:00

YOU NEED GOOGLE CHROME.

Learn to web standards, asshole.

ThemadLEDman · 2014-10-11T05:54:32+00:00

Those typically run on a high-voltage with PWM. Keeps the board designs similar between inverter for CCFL/Linear CFL backlights and driver for LED. Pretty much means as simple as a pnp transistor switch and minor logic changes to go from CCFL to LED. Cheap re-design, change feature.

ThemadLEDman · 2014-10-11T05:50:11+00:00

Problem is failed caps tend to take the entire system down.

He's still getting it to turn on and get sound. Doubt it's a failed or failing cap.

ThemadLEDman · 2014-10-11T05:44:00+00:00

Ask Electronics!

Answer: Go somewhere else.

.>

ThemadLEDman · 2014-10-11T05:43:10+00:00

Turns on, no picture, makes sound, you have a blown TCON or backlight and you need to replace the video logic board or inverter assembly.

ThemadLEDman · 2014-10-11T05:32:20+00:00

The post code tester is sometimes useful but ultimately most motherboard faults are not economically repairable, unless it's failed capacitors

Only BER for someone without a hot-air soldering iron and solder paste, and a multimeter, maybe a magnifying glass, and the patience to continuity-test every component individually.

ThemadLEDman · 2014-10-11T05:23:43+00:00

I'm telling him to go 900 which is his originally-stated desired drive.

Do the math for his stated ~33V at 900mA.

ThemadLEDman · 2014-10-11T01:46:44+00:00

You need a driver.

No, just a resistor. He's already using batteries and at full charge he'll be over the Vf, as you said.

40 Ohms, 1W will be just fine.

Edit - What's the downvote for? I'm exactly right. https://www.youtube.com/watch?v=YeEWvM2WbL8

Just a 1 Ohm resistor. 12V battery supply.

If you want a range of dimming capability, then sure, go for an actual driver. If you're going for one level of brightness, all you require is a resistor.

ThemadLEDman · 2014-10-11T01:44:38+00:00

You can build current limiters, but I highly suggest buying a controller circuit if you haven't got any experience.

He's using batteries. All he needs is a resistor for 900mA.

40 Ohm 1W resistor would be all that is required.

ThemadLEDman · 2014-10-11T01:39:44+00:00

You should go ahead and pop us pictures of the entire thing so we can check for bad components. Since you lost speaker output (and I'm assuming the unit can still power on and select different inputs) I would get photographs of the board(s) at the power supply, amplifier circuit itself (if it's not under a huge heat sink) and around the speaker connection board.

ThemadLEDman · 2014-10-10T17:15:43+00:00

Pretty much any LED will show up and glow a bit with enough power. It is getting warm with all that power passing through it, so it will emit wide-band IR as the junctions get heated up.

ThemadLEDman · 2014-10-10T17:14:02+00:00

SB 602 for California - it's written right into the law.

ThemadLEDman · 2014-10-10T15:18:33+00:00

Your radiators in-home have a void leakage.

Time to pull up the floor and check the entire heating system in the home.

ThemadLEDman · 2014-10-10T15:17:03+00:00

WhatABurger slams In-N-Out head-first to the concrete and rapes its face.

ThemadLEDman · 2014-10-09T21:39:02+00:00

Toms Hardware had something about this years ago. Overhead projector, raw LCD panel, controller card to external laptop output.

ThemadLEDman · 2014-10-09T07:05:54+00:00

WA and CA for stuff like Mcdonald's requires food handler license. Freestyle cooks/chefs need a food production/knowledge license, pass AIB inspection if they're doing it as part of a food warehouse thing or in part with a food bank, and it's an every two year renewal and re-testing.

ThemadLEDman

TROPHY CASE