[VOLTAGE]Wrong calculations ?

[coucou]

According to OMG's website :

" Don't hold me to that, but just know that a 3 volt adapter is fine for the 3.2 volt diodes." [...]"I know that the diodes I use draw approximately 30 mA (milliamps)"


If you use 3 volts with a 30mA diodes, it's --> 3V x 30mA --> 90mW diodes !!!!
But the diodes are 5mW diodes !!
So the calculations here are wrong !!!

"Ok, That means that if your 3 volt or whatever adapter has 1 amp, you obviously have 1000mA. If one diode draws 30mA, then you can power 1000/30 = 33.3 diodes! Easy, huh! "


Because the real Amperage is :
5mW / 3 Volts = 1,66 mA and not 30 mA

And so for a adapter who got 1 Amp you can wire 1000/1,66mA = 602 diodes !!!

Am I doing something wrong here ?

[perga]

I haven't checked into any of it... but my guess is the 5mW is the power output of the diode in terms of light. I believe there is also a little resistor on each diodes board that would also consume power... etc.

Basically it means that the diodes are not converting 100% of the energy supplied to them into light energy, so to get 5mW light power takes more than 5mW of electric power.

[OverMachoGrande]

Lol... man, my calculations aren't wrong... the problem is you are using very WRONG formulas here!

I said this at that hairlasertalk forum before it went bye-bye, but with those calculations you are doing for the amps/watts... YOU NEED A NEW FORMULA! lol... There is a difference between input amps and output amps. I don't remember the exact numbers, but I only need about an amp or two to go IN to the power supply from the wall for a 300 diode helmet, but it needs about 10 amps to go OUT of it to the helmet! That's a HUGE DIFFERENCE, and yes... using one OUTPUT amp for a 300 diode helmet would mean a completely ineffetive device. In fact... we are finding that you need a bigger amount of headroom than we even though previously.

There are a few things I need to clarify on the site, such as 1) the diodes will work with any voltage from 3 to 4.5 or so, and 2) the diodes technically draw about 20 milliamps, not 30. So, we can "theoretically" put more than we thought.... BUT, that's not the way it's "practically" working out. There is some sort of weird freaky anomily when you use hundreds of diodes that causes the power supplies to have to work harder. Dr. Maricle has a phd in electrical engineering and says that the way to solve this is to simply make sure you have plenty of headroom! So, that's why I use 20amp adapters now. (even though the 15amp ones were fine). So, if you have a 300 diode helmet, you really should be using a 15 amp power supply at a minimum, and the 415 diodes helmets should be using a 20 amp one.

And yeah, Perga is right... that "5mW" is strictly about the light output, and not electricity. All of that is really basic stuff that I promised we figured out two years ago, and none of this would have worked if we didn't.

If you have any questions about this stuff... you should email someone like Dr. Maricle that runs a laser company and sells diodes -NOT a company that makes devices, by the way, because AS WE HAVE SEEN TIME AND TIME AGAIN, those snakes (especially the ones that sell higher powered diode devices) absolutely lie. They'd say "Yep, you're right... those guys are doing very bad things, but here -MY DIODE will work". ...And of course, they are big, fat liars, and completely decieving you. It's unbelievable what sort of industry we stumbled in to! I figured out all of this stuff on my own, but it was very quickly later backed up by lots of people in the forums and people like Maricle.

Yeah, I've got a lot that I need to update on that site!

Oh, you can totally "hold me to that" now! lol... My statement was correct! The only think I ever really "missed" on was using those adaptaplug things (now discontinued) because they are a bottleneck for amps, and the "flux capacitor". The "flux capacitor" is theoretically sound, but it takes so much abuse that it ends up being a source of major problems. That's why we dumped it!

[xyion1]

/post removed to save some space

OMG, I'd like to clarify some of your statements (as an engineer). There is no disrespect intended, the community owes much of the knowledge to you and your website, myself included.

1. Coucou was not using the wrong formulas, simply the wrong numbers. You may say this is pedantic, but there are really only a few simple laws for Power/Voltage/Current. V=iR and P=iV, that's it.

2. Input current and output current indeed are different, but they are dependent on the voltage supplied and the efficiency of the converter. Ideally Power Out = Power In * efficiency. It will take > 45W input to output 45W (assuming 30ma and 300 diodes), I would estimate 56W (or roughly 600mA of 120 VAC).

3. The weird freaky anomaly you are referring to is most likely due to the loading of the power supply. As you get closer to the max current output of the supply, the efficiency drops. Also, the more wire length there is, the more resistance, and the greater the voltage drop. Another cause is the number of connections made (through tier 1, 2, and 3 connections). The wire nuts are handy, but there is a voltage and current drop through each one of those connections. I can't postulate to what it is though. This is why a larger supply yields better results, it isn't being taxed as much, and it can pump out more current as required.

The easiest thing to do is to use a power supply with sense lines, and wire the sense lines in parallel with a laser module. This will ensure that there is no voltage drop over the line since the supply can adjust the voltage it output to compensate. Minimizing the # of wire nuts/connections will also be good, but thats not as easy and will could involve using a specialized harness or a circuit card assembly with low impedance traces.