About to take the plunge into modding.

I have been collecting flashlights for a while now, and I have been reading the forum for a while and you have all inspired me!

I now want to have a go at modding flashlights, especially some of the ones I have purchased from DealExtreme prior to discovering Fenix, JetBeam, NiteCore, 4Sevens.com, LightJunction.com, BatteryJunction.com, ......, and this forum.

However, the big problem is I just don't get it :sigh: !

My apologies up front if I'm asking really basic questions now and in the future, but I really want to get to grips with it, so I'm asking for your patience and understanding.

My first question is in regards to matching up emitters and drivers.

I read the threads and they mention particular drivers and emitters, and I do searches at shiningbeam.com and DealExtreme.com and I try to match drivers to emitters but I don't know if I'm doing it right.

For example, most of the information on emitters quotes a 'typical driving range'. As an example, Emitter SKU 12721 at DealExtreme.com quotes a driving range of 3.6 to 3.7 voltage input.

If I now want to match up a driver for this emitter, is it as simple as finding a driver that has a 3.6 to 3.7 voltage output?

What about the mA values. The emitters don't seem to quote mA values, only the drivers do.

As an example, I have looked at two drivers for the emitter above. First off SKU 7612 at DealExtreme.com. It quotes 3.7 volts and 1000mA output. Next I have looked at SKU 1271 from ShiningBeam.com. It quotes a voltage range of between 2.8 and 8 volts INPUT (the other quoted OUTPUT voltage). However, this one quotes output currents of 140mA, 1000mA and 2500mA but does not quote the output voltage.

So one driver quotes output voltage and current, but the other quotes input voltage and output current, but emitters only specify input voltage. How do I know if the mA output values from the driver are safe for the emitter, if the emitter specifications don't quote it, but drivers do? How do I know if it's OK to run the driver with 2500mA output for this emitter?

It's really confusing and the more I read the more I get confused.

What am I missing here or am I destined to only buy flashlights and leave modding to the experts?

Any advice would be greatly appreciated.

Regards,
bedazzLED

While I don't have all the answers, I'll try to help you all I can until someone more knowledgeable than myself joins in.

For your first question about drivers. You always want to match all three components so they work together. The emitter will have a max rated current that it can handle, as well as, a vf or voltage forward rating. There are different types of drivers. You've got buck drivers, boost drivers and linear drivers. The driver you choose should be able to work with your batteries and emitter. For example, I like to use 7135 based drivers, but the maximum voltage they can sustain without heating up and possibly being damaged is 6 volts.

So, if I have a flashlight that accepts 2xRCR123's, I have to either choose a different driver or change my battery setup to a 17670 or 17650. The reason for this is each of the previously mentioned batteries has a charged voltage of 4.2volts, so if I were to use 2xRCR123's in series, I would have a combined voltage of 8.4volts, which would probably burn the 7135 chips up. I'm going to recommend that you go to CPF member, TorchBoys driver list. Just click here.

There's a boatload of driver information there, including where to buy and prices. The DX SKU 12721 is an SSC (seoul semiconductor) P7. If that's the emitter you're looking to use, you can do a search on ssc p7 and you should find a pile of information on here. As far as finding emitter specs, it's usually best to go directly to the manufacturer and look at there spec or datasheet for the information. Generally, you'll find that DX and the like will leave out certain parts of information.

Both drivers you're looking at are linear regulator drivers (7135 based). Go to the above link and scroll all the way to the botttom and click on the 7135 link at the bottom of the page (good reading). Also, search 7135 or AMC7135 on here, again you'll find a boatload of information. Both of the drivers you're looking at have a max input voltage of 6volts. The driver at DX is a 16-mode board while the Shiningbeam is a 3-mode board (low, medium and high modes, I prefer this one myself). The other difference is, the DX board has a total drive current of 1000ma or 1A on high. This is because it has 3x7135 chips on it. Each chip raises the current output by roughly 350ma. The Shiningbeam driver has 8x7135 chips on it for a total of 2500ma or 2.5A on high (2.8A if you change out the small supplied wires, but that's another story all together).

The shininbeam driver is what I'd recommend you buy if you want to drive an SSC p7, because 2.5-3A is just right for that emitter, as long as it's going in a light with enough heatsinking (like a maglite). You can use the AMC7135 boards (DX boards), but to get the current up, you'd need multiple boards or you'd need to add additional 7135 chips to the existing board and it would require more soldering.







Don't get discouraged; everyone has to start somewhere, but you're right, it is a lot of information to take in. Just keep reading and trying to learn and you'll have all the basics covered in no time.


Casey

"(2.8A if you change out the small supplied wires, but that's another story all together)."

I feel you. I just got my SB drivers in and there really is MORE insulation than wire there.:shrug:



To bedazzLED: It is easy to feel overwhelmed. I can understand how you feel. I was there not too long ago. Just keep at it. It will slowly start to make sense. There are others to help you too. :grouphug: lovecpf

TiForce made some very good points.

I think you need to start by getting a pen and paper and ask basic questions before every mod and write down the values.

For example a MAG (I love mags) But hold true for others too:

1. What is my host? 3D mag
2. batteries are in it? 3 Ds
3. What voltage do those batteries add up to? 3.6-4.5 volts (alkalines vs. NiMh)
4. What LED do I want to use? Most popular options right now are P4,P7, MC-E, XP-G, XR-E, SST-50,SST 90. Let's say you want a P4. Look up the data sheet for a P4. The Spec on a P4 is 1 Amp and it likes 3.25-3.7 volts.

So now you know you have more volts available from your batteries than needed. Right? So you need a driver ( a buck ). You need a driver that will bring down voltage to keep the LED happy at about 3.25 volts, and feed it current to about 1 amp. So you search your favorite vendor to get a driver that will give you those requirements.

• 5 Shining Beam has a driver you could use SKU 1060 or SKU 1219.

SKU1060 will give you 800 mA right? You P4 can handle up to 1 AMP. So your LED will be underdriven by 200 mA. It will not fry it. This will work.

Or Choose SKU 1219 and it will drive it at a max. of 1.2 AMPs or 1,200 mA. Your LED likes 1 AMP, So now you are over driving it a little but not by that much that it will fry it. So this too works.

Remember you can UnderDrive something but not OverDrive by a lot it otherwise

If you follow the logic it makes sense till you can build this stuff in your head. Hope this helps you. I still have a lot to learn too, but coming here everyday and asking questions even stupid ones helps.

Its, not hard !

As mentioned ..

Batteries will dictate what you can do , or cant do ...

So this is where you need to start :

Then you need to make sure you can match a driver to the voltage your going to run :

And then see about the emitter which will work the best with the battery driver combination ...

Its a balancing act ,

Drivers : Depends on what battery :
Boost driver = will boost voltage to LED
1xAA battery = 1.5v LED may be 3.5v = very poor performance ... Add a boost driver to boost voltage to increase LED performance

2xAA = 3v LED may be 3.5v = still not very good performance , add a boost driver to increase performance

3xAA = 4.5v , LED may be 3.5v = Fantastic performance but now you run the risk of damaging the LED with too much voltage , so you add a driver to regulate the voltage to the LED [ usually 3.7v ? ]

This is a simple explanation : The driver is there to regulate the voltage - current to the LED ...

Current = Amps x Voltage = Watts

A lot of drivers will be listed by current mA [ milli Amps ] or and by Watts ..
As for the LED

5MM Generic LEDs (0.5-5 Lumens ea)
5MM Nichia LEDs (5-10 Lumens ea)
Any Generic "High Power" LED (10-70 Lumens, varies wildly)
Luxeon I (40 Lumens @ 350ma)
Nichia IO Moon (45 Lumens @ 350ma)
Luxeon III (80 Lumens @ 1000ma)
Luxeon V (87-120 Lumens @ 700ma)
CREE P2 (67-73 Lumens @ 350ma)
CREE P3 (73-80 Lumens @ 350ma)
Luxeon Rebel 80 (80 Lumens @ 350ma)
CREE P4 (80-87 Lumens @ 350ma)
Luxeon K2 PWC4 (85 Lumens @ 350ma, 250lm at 1500ma)
SSC P4 T Bin (70-91 Lumens @ 350ma)
CREE Q2 (87-94 Lumens @ 350ma)
CREE Q3 (94-100 Lumens @ 350ma)
Luxeon Rebel (100 Lumens @ 350ma)
Edison Optics KLC8 (100 Lumens @ 350ma)
CREE Q4 (100-107 Lumens @ 350ma)
SSC P4 U Bin (91-118 Lumens @ 350ma)
CREE Q5 (107-114 Lumens @ 350ma)
Osram Golden Dragon Plus Ultra White (120 Lumens @ 350ma)
CREE R2 (114-120 Lumens @ 350ma)
CREE MC-E K Bin (370-430 Lumens @ 350ma)
CREE MC-E M Bin (430-490 Lumens @ 350ma)
SSC P7 B Bin (570-700 Lumens @ 2800ma)
SSC P7 C Bin (700-800 Lumens @ 2800ma)

LED output is sort of measured @ 350mA current
So in theory a 1A driver + say a Q5 emitter on paper can do 300Lumen
Butt !!! You need to factor in HEAT , driver efficiency , the quality of the LED , heatsinking , LENS loss , and a few other things , and the real output might be more like 33% less ...

The only thing you can do is read more , until it makes sense ... and ask more questions ...

Read the CPF FAQs and stickies, which explain a lot.

Use Google to find, download, and read the datasheets for the various LEDs of interest, e.g., Cree XR-E, Cree XP-G, Cree MC-E, Seoul P4, Seoul P7. Also download the binning and labeling PDFs for those LEDs.

The datasheets will list the maximum input current (i.e., forward current, or drive current) that the manufacturer recommends. The Cree XR-E and Seoul P4 are rated to 1000mA. The Cree XP-G is rated to 1500mA. The MC-E and P7 combine four separate LED dies into a single unit, and each die is rated to a max of 700mA. That gives a total of 2800mA drive current for those multi-die LEDs.

LEDs should ideally be powered by a constant current driver, which is usually the case (but not always) with the flashlight drivers that are available. Driver selection depends on the power source (e.g., the total voltage that your batteries can deliver, as well as their ability to deliver current), the drive current you wish to deliver to the LED, physical size (e.g., a 17mm driver is the standard size to fit the so-called brass "pill" used in most SureFire P60 compatible drop-ins).

If, for example, you are using 2xC NiMH in a C Maglite LED mod to drive a Seoul P4 at full power (1000mA drive current), you will need a driver that boosts the output voltage from your input (battery) voltage of about 2.4V to about 3.5V, which is approx the forward voltage of a P4 when driven at 1000mA.

Conversely, if you are using 2xLi-ion, with a total input voltage under load of about 7.4V, then you will need a driver that reduces (bucks) the output voltage down to the ~3.5V you need to run your P4 at full power.

There is also the concept of the driver running in "regulation". That basically means that you are feeding the driver with the voltage and current it needs to output the driver's rated output current. For a buck driver, you often need to deliver about 1V above the LED's forward voltage for the driver to run in regulation. This is the buck driver's voltage overhead.

For a boost driver, the limiting factor is often how much current the boost driver can handle to deliver its rated output current. The amount of current that the boost driver can handle is not infinite.

The key equation for drivers is

power generated by the driver = power used by the LED

Power generated by the driver is given by

driver efficiency * battery voltage delivered to the driver under load * battery current delivered to the driver under load

Power used by the LED is

LED forward voltage * LED forward current

For the boost driver example above, if the driver efficiency is 80% (fairly typical value), then

0.80 * 2.4V * Ibatt = 3.5V * 1A

Solving for Ibatt, we get ~1.8A. If the boost driver can't handle 1.8A input, but instead maxes out at say 1.5A, then you aren't going to be able to run in regulation with this boost driver and deliver 1000mA drive current to the LED.

Typically, modders pick a driver that delivers full power to the LED they want to run. But there is no law of physics that forces you to do that. Underdriving an LED can, and has, been done, and can be advisable for various reasons, e.g., reduced heat generation, longer run time, and/or working within the driver's specs to run in regulation.

The datasheets contain graphs of LED forward current vs forward voltage, as well as relative lumens vs forward current. LEDs don't have a single value for the amount of current at which they can be driven. It is a range, with a manufacturer-specified max.

For a given driver's forward current, you can use the datasheet curves to estimate the forward voltage and the relative lumens factor for that forward current. Then multiply the relative lumens factor that you've found by the LED's lumens rating, which is typically done at 350mA, to arrive at an estimate of the total lumens you might get at the drive current of interest. That's how folks arrive at estimates such as a Cree XR-E Q5 lumens bin LED delivering about 240 lumens when driven at 1000mA. The Q5 bin is rated at 107 lumens when driven at 350mA. The relative lumens factor at 1000mA is about 2.2. Thus, 2.2 * 107 ~ 235 lumens. So if you use a driver that delivers 1000mA drive current and use that driver to run a Cree XR-E Q5 bin LED, you might get about 235 lumens from the emitter. The actual "out the front" (OTF) lumens is generally less because of various optical losses (mainly from the reflector or focusing lens, and any protective glass window).

The eqn and calculations above also show how you might estimate run time. You can calculate (or measure, if you have a multimeter) the battery current draw under load. The batteries will have a capacity rating printed on the label. Let's say you calculate a current draw of 0.5A (500mA). If your batteries have an advertised capacity of 1000mAh, then you will get about 1000/500 = 2 hours run time.

Hello all.

All I can say is WOW and thank you so much!

This is a wealth of information from all of you and that's why I reckon this forum is fantastic, everybody is so willing to help a newbie.

OK, so no I have all the good info, I'm going to do my homework and start doing some practice matching up drivers to emitters.

From time to time I'll post back with what I think are good matches, and ask for your opinions of the match-ups and any advice if my matching up is off track.

Again, thank you to everybody for all the fantastic information, pointers and links.

This is just fantastic, I'm excited lovecpf !


Regards,
bedazzLED.