LEDs in parallel

I was talking about diode series resistance, part of the issue of paralleling LEDs, and JF got into his usual clucking and whining mode.

Do you own any LED flashlights? Open one up and see if there are any resistors.

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin
Loading thread data ...

Mine are not the dumb versions. The switch, and control circuit is in the tail. That means that it takes the 4.5 volts in and correctly controls the feed to a single, super-bright LED with 3 distinct modes.

It is so well designed that when your batteries begin to avalanche, the second mode no longer functions precisely as designed, signaling the operator to use the first mode or third mode, but to also prepare to replace or recharge your cells. The 'nose' end of the battery pack gets applied directly to the LED. The circuit and equivalent limit resistance presented to the virtual series circuit and LED and power source resides in the tail of the lamp and is electronic. Bike riders use similar LED drivers units in headlights that flash (tail lights too).

I know more about LED flashlights and bike lights than a "see if there are any resistors" dope like you ever will.

Reply to
Hattori Hanzo

Cool. How does it actually work?

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin

It is beyond your grasp, resistor boy.

Go read your degreaser manual.

Reply to
Hattori Hanzo

I think all you know about that flashlight is how to push the button on the end.

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin

You give him way too much credit, John.

Reply to
John S

degreaser is that your employees use it, not you. The reason is because even that simple device is beyond your understanding.

So you are not going to understand the drive circuit in my LED lamp.

Hell, it took you nearly a decade to figure out how to add a pathetic, self aggrandizing sig to your pathetic, abusive posts.

Reply to
Hattori Hanzo

He knows how to push your buttons. :(

--
You can't have a sense of humor, if you have no sense.
Reply to
Michael A. Terrell

In other words, you don't know?

Jamie

Reply to
Jamie

--
Actually, I did peruse two of those sites and found that with the
voltage drop across the diode, at the currents you mentioned, both
cases resulted in real-world power dissipation in excess of the limits
allowed.

In addition, the Fairchild site which, in figure 5, clearly plots the
ordinate in millivolts, is wrong.

Apparently not having noticed that, I suspect you'll now make excuses
and bitch on forever about how unimportant accuracy is.
Reply to
John Fields

Now you are weaseling.

It's not a matter of "accuracy", it's an obvious typo. The axis is obviously volts.

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin

--
Nope, just stating a fact.
Reply to
John Fields

The y-axis on that fig 5 graph is obviously volts, and the "m" is obviously a typo. Given that, there's no accuracy problem. My job is to design stuff, not freeze in my tracks at the slightest excuse.

If you look at a smattering of 1N4148 data sheets, there's a huge spread of I-V curves. So I certainly wouldn't design a circuit that depends on the high-current I-V curve without making sure we'd purchase only one vendors's parts, and even then it would be risky. I wouldn't depend on their capacitance or reverse leakage behavior, either. 1N4148 is a very sloppy part.

All of which is aside from the issue of paralleling LEDs, which lots of people seem to do.

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin

Cool, let's talk about that:

OK, you have your super multimode Wal-Mart LED flashlight, maybe with optional laser pointer. The question is, how does it regulate the LED current? Inductive boost? Capacitive charge pump? Resistor? Linear or PWM current-regulator IC? Raw battery connected to LEDs?

You could take it apart and see what's inside. Or you could search the web for controller ICs. Or, more fun, you could learn some things about the issue without opening the flashlight at all.

Any ideas how?

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin

I don't know either. He should tell us how his flashlight regulates current. Or, if he doesn't know (which he doesn't) he could do a little work to find out, and tell us. Which he won't.

--

John Larkin, President       Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply to
John Larkin

What is this another attempt at a social insult?

Fuck off and DIE, John Larkin. You are a sad excuse for a civil, intelligent man. That may well mean that you qualify for none of the three titles. Likely even. You are worse, in fact, than Ross Perot could have ever been. And his remarks were not racist. It was just a poor choice of words. You actually were trying to be insulting. Big difference.

It means that a real, intelligent man like Ross has more honor and character than an insulting, pathetic, self aggrandizing piece of shit like you ever will.

Reply to
Bart!

Interesting that you would take a slight of a *flashlight* as such a personal insult....

...it's like he was insulting your manhood. You certainly respond as such. I wonder what Freud would have to say?

Reply to
krw

The first time you have spoken the truth in this group in quite some time.

I would, but only if it is MY desire, you pathetic, cringing little milksop.

Back to the lying horseshit behavior already, I see. There was a time when a man would simply drop you where you stand for pathetic, uncivil behavior like that. That is where the Colt motto came from.

You are an idiot.

For all you know, utilization of LEDs is what will make me rich.

Fact is, you don't know a goddamned thing, you pathetic, characterless, honorless piece of shit.

Reply to
Bart!

You mean it is the first time you have understood comments made from JL in a long time?

I am sure it would be your desire to do so, if you only knew, and then most likely would be a case where we wouldn't be able to shut you up!

And there were and still is, times where the pen is mightier than the sword.

Yes, how shameful of him to make such rude remarks about you doing work!

Well, there is a sucker born in every crowd. I am sure with your skills you'll be able to find some. Most people tend to hang with their own kind.

He may appear to you to be character less in your eyes, but I believe that would be due to lack of time on his part, wasting such traits to pamper the likes of you.

Have a good day, I am sure i'll be next on the list.

Jamie

Reply to
Jamie

It's truly amazing what woman are pushing out these days.

Jamie

Reply to
Jamie

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.