# Romisen RC-G2 w. Cree R2 (update - detailed instructions).



## meuge (Feb 13, 2008)

I was very excited when I modded my first G2 with an SW0 SSC and the SKU7880 board. It was bright... somewhere between the Medium and High settings of a Fenix L2D-CE. 

However, I wanted more. So here it is - the pursuit of the "pocket searchlight". 

Shopping list:

1. Romisen RC-G2 (naturally) from DX
2. Cree R2-bin XR-E emitter (bare) WG bin (CPF marketplace)
3. SKU7880 board from DX
4. MCB650 Cree mounting PCB from the sandwich shoppe.

Tools/Supplies:

1. Soldering Iron (15W radioshack type)
2. WBT 4% silver-bearing solder (partsexpress)
3. Arctic Silver 5 Thermal compound (newegg)
4. Dremel w. various bits (Home Depot)
5. Curved forceps
6. Straight forceps
7. Curved Hemostat
8. Needle-nose pliers

I will write up the exact procedure a little later, but without further ado, the beamshots.

RC-G2 vs Fenix L2D-CE LOW





RC-G2 vs. Fenix L2D-CE (medium)




RC-G2 vs. Fenix L2D-CE (high)




RC-G2 vs. Fenix L2D-CE (turbo)




Sorry about the color, but I haven't fully figured out how to use the camera. In reality, the color of the R2 WG bin is much closer to that seen in the 2nd pic - very CREAMY white... with a slight tinge of yellow... very warm and pleasant. 

In ceiling bounce tests, the light seems to unbelievably tie the Fenix L2D-CE P4 on Turbo, which means it's putting out at least 135 lumens at the emitter, on just a single AA. 

As you can see from the pics (and if my camera could underexpose more, I'd do it), the hotspot of the RC-G2 is significantly brighter than the L2D-CE on Turbo, and this is even more readily apparent in real life. This is amazing, given that my L2D-CE has a smooth reflector. A quick look outdoors puts this light in the Fenix T1 category, in terms of throw. When I get my T1 and the SSC-modded RC-G2 from my friend (borrowed it for hiking), I'll do an outdoors comparison. 

For those who want to do this mod, here's a quick overview:

0. Remove the pill, by rotating it out using needle-nose pliers or curved forceps.
1. Unsolder the driver (I used unsoldering braid)
2. Unsolder the P2 LED
3. Remove the pill (I used a small flat-head screwdriver)
4. Remove the star and the LED (I ripped it out using pliers)
5. Use a rotary tool to enlarge the hole at the back of the pill as much as possible (take off ~0.4mm)
6. Use a rotary tool to shave about 0.8mm from every edge of the 7880 driver
7. Prepare the emitter by flowing a little bit (<0.5 mm^3) of solder onto the terminals
8. Prepare the PCB star by flowing ~2 mm^3 of solder onto the back of the emitter terminals. Place thermal compound on the back of the emitter. 
9. Cut out holes for the wires in the MCB. I used a dremel with a cutoff tip, and simply cut straight lines into the MCB 180 degrees from one another. 
10. Place the emitter exactly into the correct position on the PCB, then carefully allow the solder to reflow, while pushing gently down on the emitter. I clamped it down using hemostats, which allowed the bottom of the emitter to come down onto the MCB base. 
11. Place the driver in its proper position, and thread the wires through the holes in the pill. Solder them to the MCB solder points. 
12. Test the light engine to make sure the LED lights up, and test battery draw. Assuming 600mA to the LED, and an 80% efficiency of the driver, you should be getting 2-2.5A draw from the battery. 
13. Solder the driver negative rings to the pill (I prefer doing it in at least 4 points, for lower resistance, and a stronger bond. 
14. Place thermal adhesive under the MCB, then use forceps to lower the MCB onto the compound, then press and twist. Take care to ensure that all the slack wire goes into the pill, and the underside of the MCB contacts the pill fully. 
15. Also add thermal adhesive around the places in the driver rim where it wasn't soldered. This will permanently mount the driver, and ensure that it won't come loose from shock if the light falls. 
16. Screw the pill into the light. 
17. Place the isolation plastic ring onto the LED, the screw the head down, so that it secures the LED assembly and let the epoxy cure for 20-30 minutes. 
18. Insert battery and enjoy!


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## gunga (Feb 13, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

Very cool.

Is there another driver that would work well without the 20 modes?

I would prefer a 3 to 5-ish mode driver, not 20. Does it switch modes easily (by accident?).

Also, do you find better beam pattern with cree vs Seoul?

Interesting...


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## f22shift (Feb 14, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

like a cheap jetbeam pro :nana:


i'd rather put the r2 in the l2d but this is really cool. how much would you estimate the total cost to be?


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## BruceD (Feb 14, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

Thanks - I appreciate the excellent lists stating where you got the stuff!


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## meuge (Feb 14, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



gunga said:


> Is there another driver that would work well without the 20 modes?
> 
> I would prefer a 3 to 5-ish mode driver, not 20. Does it switch modes easily (by accident?).


I converted the 7880 driver into a single-mode by re-soldering the negative lead to the outer rim. 

In general, multi-mode on one-stage forward clickies is VERY awkward, as it renders the forward switch useless, due to constant changing of modes. I tried it with my first mod, and immediately changed it. 

Also, the 7880 driver hums VERY loudly on all modes <100%, so it's very annoying. 

The only other driver I'd use here, would be the MadMax, but it's $13 + shipping, as opposed to $4 and free shipping. 


gunga said:


> Also, do you find better beam pattern with cree vs Seoul?


Both beams are ringy with this reflector, but the Seoul is smoother, as always. However, because the Seoul isn't perfect with regards to height, the spot isn't really comparable to the Cree. So while the brightness is much better than stock with the SW0, the throw is significantly enhanced with the Cree.


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## meuge (Feb 14, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



f22shift said:


> like a cheap jetbeam pro :nana:
> 
> i'd rather put the r2 in the l2d but this is really cool. how much would you estimate the total cost to be?



I probably will put an R2 into the L2D, or I may wait till R3 or whatever. Mainly, I thought it would be fun to make a really small, but really throwy light, with a forward switch. 

About the cost, 

RC-G2 - $11
7880 - $4
LED - $10
PCB - $3
Misc (consumables) - $2
---------------
Total: $30

Considering that I didn't need to buy any of the tools or supplies to do this, I think $30 for this light is a bargain. I will likely drown all soldered parts in thermal epoxy, to make sure they hold if the light is dropped, but otherwise I think it's pretty set.


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## gOhAsE (Feb 14, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

The two RC-G2s I received 10 days ago had glued pills. Very very hard to remove it.

What I wanted to ask: How much current is the light drawing in Low - Mid - High?

The one I modded a few hours ago draws 0.4, 1.1 and 3.1 Ampere from a single eneloop nimh.


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## Jarl (Feb 15, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

Very nice indeed. What purpose does the MCB650 serve? I already have some LED's I could use, and since I'm UK based getting the MCB's could be tricky.


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## meuge (Feb 15, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



Jarl said:


> Very nice indeed. What purpose does the MCB650 serve? I already have some LED's I could use, and since I'm UK based getting the MCB's could be tricky.


The LED in the RC-G2 is on a small star-board, which is used as a heatspreader. Thus, a spacer is required between the pill and the LED, to have the LED sit high enough to fit into the reflector properly. Also, it's easier to reflow solder the emitter onto the MCB, and then solder the leads to the joint, rather than soldering bare leads to the LED. 

The MCB is NOT needed, and shouldn't be used, if using an SSC emitter... only a bare Cree.


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## Jarl (Feb 15, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

That's good to hear. I'll try to bodge something out of spacers and a few rebels I own. great guide; I'm going to use these as my loaner lights- 2 high power, 1 with a 400ma micropuck.

edit: Do you know how much current the LED is getting?


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## Flashlike (Feb 16, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



meuge said:


> ...The only other driver I'd use here, would be the MadMax, but it's $13 + shipping.



Meuge--
If I spring for the MadMax driver, which one would you recommend? There are two different converter boards listed on the Sandwich Shoppe (both $13). The one is called "MadMax Lite" and the other one "MadMax Plus".


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## meuge (Feb 16, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



Flashlike said:


> Meuge--
> If I spring for the MadMax driver, which one would you recommend? There are two different converter boards listed on the Sandwich Shoppe (both $13). The one is called "MadMax Lite" and the other one "MadMax Plus".


Madmax Plus is 700mA output, versus 350mA of Madmax Lite... so definitely Plus. 

P.S. My recent unofficial tests put the RC-G2+7880+R2 in dead heat with a Fenix L2D-CE in terms of output, and maybe 30-40% better, in terms of throw. I'll post the results when I have a chance to quantify the tests properly.


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## jinx626 (Feb 27, 2008)

what is the runtime on this modded?


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## meuge (Feb 27, 2008)

jinx626 said:


> what is the runtime on this modded?


00:50 - 1:00 of regulated output, using a 2000mAh Sanyo Eneloop NiMH rechargeable battery.


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## clg0159 (Mar 1, 2008)

For replacing the led could you just swap the emitter/base with an emitter on a 16mm base? I have no experience reflow soldering.


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## meuge (Mar 1, 2008)

clg0159 said:


> For replacing the led could you just swap the emitter/base with an emitter on a 16mm base? I have no experience reflow soldering.


Yes you could - DX now has Q5 WC available on a 16mm base. 

The only downside is the cool WC tint... I prefer WG or WH for a warmer color. On the upside, it'll appear brighter. 

As far as reflow soldering goes, this was my first time doing it. 

The way I did it was to use my soldering iron to warm up each of the pads (2 on the emitter, 2 on the board) one at a time, and apply a tiny bit of solder to the pads (only flows when they're hot enough). The copper pads on the PCB are wider than the base pads of the emitter, so a little solder will show when the emitter is mounted... and that's what we want!

Then I clamped the emitter in the correct position over the pads (everything is primed with solder) using 2 curved hemostats. I then applied the iron to each side separately, warming the tiny bit of solder that stuck out on the side. This transmitted the heat to the underside of the emitter, and within 2-3 seconds using the iron set to 30W the primed solder reflowed, bonding the emitter to the PCB. I then did the same thing on the other side. Because the hemostats were squeezing the emitter and the board together the entire time, when the solder became liquid, the emitter landed onto the board with almost no gaps. To make sure, I repeated the procedure. 

I didn't solder the underside of the LED, but instead left about a 1/4 grain of rice dab of Arctic Silver 5 on it, which got squished when the LED was soldered to the board ensuring an excellent thermal path. 

I've run the light from full charge to empty, and it gets very warm... but the brightness or tint don't change... so the regulation of the 7880 circuit is good at >45 minutes of dead-flat brightness, and the heatsinking of the RC-G2 is sufficient.


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## clg0159 (Mar 1, 2008)

I appreciate the info. That sounds like a good method. Now if only I could find an R-bin XRE! arghh......I have all of the pieces, but will wait to find the appropriate emitter. I really prefer the tint I have seen on the R2's to the the Q5 WC. Thanks again


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## meuge (Mar 1, 2008)

clg0159 said:


> I appreciate the info. That sounds like a good method. Now if only I could find an R-bin XRE! arghh......I have all of the pieces, but will wait to find the appropriate emitter. I really prefer the tint I have seen on the R2's to the the Q5 WC. Thanks again


No problem. 

The other thing you could do is use the Q5 WG on star that DX sells, and just trim the board to fit. 

That's what I am going to do to my RC-F4 tomorrow.


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## clg0159 (Mar 1, 2008)

Yeah, I have already ordered some(DX).......but who knows, by the time I recieve my order someone may have the R2's in stock or lumileds may fix the K2 epoxy problem(I love these)! What a great time to be a flashaholic!


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## clg0159 (Mar 6, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



meuge said:


> I converted the 7880 driver into a single-mode by re-soldering the negative lead to the outer rim.
> 
> In general, multi-mode on one-stage forward clickies is VERY awkward, as it renders the forward switch useless, due to constant changing of modes. I tried it with my first mod, and immediately changed it.
> 
> ...


 

Well, the madmax apparently will not work with a single AA setup according to post#14 here:
https://www.candlepowerforums.com/threads/191168

Anyone know why that might be?


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## meuge (Mar 6, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



clg0159 said:


> Well, the madmax apparently will not work with a single AA setup according to post#14 here:
> https://www.candlepowerforums.com/threads/191168
> 
> Anyone know why that might be?



Eeep... I didn't notice that before

While it has an input voltage range of 0.8V to 5V, it only outputs 3.1V, so it won't do well with high Vf LEDs. I would guess it would work with a Rebel... or an SSC U-bin.

Well, 7880 it is then... since it's a great board for 1xAA.


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## taschenlampe (Apr 5, 2008)

Does anyone know where the thread: “Romisen MXDL *RC-G2* Cree experience?” is gone?

Can’t find him …:shrug:

tl


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## kavvika (Apr 5, 2008)

tl: It is being worked on as we speak.


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## gunga (May 1, 2008)

Cool. I just picked up an unglued G2 qith Q5 from Shiningbeam. Now I'm tempted to try a multi-level mod with some more pop.

ANyone tried this board?
(5 mode, max 500 ma).

http://www.dealextreme.com/details.dx/sku.7302

Man, I was happy with the light stock, now I'm temped to mess with it!
Not a fan of all the dremel work needed tho.

:sick2:


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## StefanFS (May 18, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



meuge said:


> I converted the 7880 driver into a single-mode by re-soldering the negative lead to the outer rim.
> 
> In general, multi-mode on one-stage forward clickies is VERY awkward, as it renders the forward switch useless, due to constant changing of modes. I tried it with my first mod, and immediately changed it.
> 
> ...


 

I started using the '3W 19-Mode Universal Regulated Circuit Board', DX SKU 7882, with these lights. It's a bit messier to mount them: You need to take off 2 mm from the lower part of the pill, put an o-ring around the edge of the driver that will rest against the ledge in the battery tube. The driver is loose and is pressed against the cut down pill by the o-ring and the battery pressure. It's also necessary to shorten the battery spring in the tailcap a bit for less pressure.

I made a few of these with CREE Q5 on 14mm boards, it's an economical solution and I get a high quality driver that's adjustable in voltage/current. Battery draw is much less compared with the 7880 driver, 1.7A compared to 2.5-2.7A while output is higher and the emitter see more mA. It's a more efficient circuit. A bonus is that it doesn't hum and that one user interface is low-med-high only. And it works very well to change levels with this forward clicky.

Stefan


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## geek4christ (May 18, 2008)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



StefanFS said:


> I started using the '3W 19-Mode Universal Regulated Circuit Board', DX SKU 7882, with these lights. It's a bit messier to mount them: You need to take off 2 mm from the lower part of the pill, put an o-ring around the edge of the driver that will rest against the ledge in the battery tube. The driver is loose and is pressed against the cut down pill by the o-ring and the battery pressure. It's also necessary to shorten the battery spring in the tailcap a bit for less pressure.
> 
> I made a few of these with CREE Q5 on 14mm boards, it's an economical solution and I get a high quality driver that's adjustable in voltage/current. Battery draw is much less compared with the 7880 driver, 1.7A compared to 2.5-2.7A while output is higher and the emitter see more mA. It's a more efficient circuit. A bonus is that it doesn't hum and that one user interface is low-med-high only. And it works very well to change levels with this forward clicky.
> 
> Stefan



Thanks for that report. I did not realize the efficiency was so different.

It seems that those boards are now shipping in a crippled state that requires a slight modification to get all levels. Not too big of a deal if you follow the instructions in this thread, but a pain nonetheless.


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## dealgrabber2002 (Aug 30, 2008)

Anyone know where I can get a smooth reflector for the RC-G2?


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## moviles (Feb 28, 2009)

i think the way to make the most powerfull output its make it direct drive, direct drived dont will work wit 1.2 ni/mh or 1.5 batteries, but with 14500 it will be really powerfull,i think protected 14500 can give 1.4 or 1.5 amps on this rc-g2/r2 flashligt, 
no way to buy the r2 for this rc-g2 in dealexreme????


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## superstylefactor (May 5, 2009)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*



StefanFS said:


> I started using the '3W 19-Mode Universal Regulated Circuit Board', DX SKU 7882, with these lights. It's a bit messier to mount them: You need to take off 2 mm from the lower part of the pill, put an o-ring around the edge of the driver that will rest against the ledge in the battery tube. The driver is loose and is pressed against the cut down pill by the o-ring and the battery pressure. It's also necessary to shorten the battery spring in the tailcap a bit for less pressure.
> 
> I made a few of these with CREE Q5 on 14mm boards, it's an economical solution and I get a high quality driver that's adjustable in voltage/current. Battery draw is much less compared with the 7880 driver, 1.7A compared to 2.5-2.7A while output is higher and the emitter see more mA. It's a more efficient circuit. A bonus is that it doesn't hum and that one user interface is low-med-high only. And it works very well to change levels with this forward clicky.
> 
> Stefan



Hi Stefan, I've been following alot of your posts ever since i stumbled on your first g2 p4 mod. With regards to the cree q5 on the 7882 driver mod, how is the low-med-high level achieved? 

Among all the G2 mod combination, which one is the best? ie p4 with 7880, r2 with 7880, q5 with 7880, or q5 with 7882? Is a p7 mod possible for the G2 or N3? Thanks!


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## AlexGT (May 5, 2009)

*Re: Romisen RC-G2 w. Cree R2 - tremendous throw on 1xAA*

I like the 7880 driver with a Q5 using eneloop AA, it does get somewhat hot, but very bright! Poor man's Jet-I! I wish they made it in HAIII

I had to use Artic silver to help transfer heat from the pill to the body of the light.

AlexGT


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## superstylefactor (May 6, 2009)

when to use artic silver, and when to use artic alumina?


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