Classic review: Romisen RC-A6

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Fritz t. Cat
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Classic review: Romisen RC-A6

As Beautiful, Unusual and Well made as its fraternal twin

★★★★★

This and the RC-A8 are the only two lights I know of that were made taking full advantage of the ability of a numerically controlled lathe to produce arbitrary smoothly curved bodies of revolution, almost like a pottery wheel. Only the Smiling Shark SS-5039 compares to them in artistic and skillful use of the medium. http://budgetlightforum.com/node/30800

Both were made in black and “silver” or “grey”, but silver RC-A6s are now hard to find.

The shape is almost a few sections of cones and cylinders fit together with rounded transitions, but most of the lines defining the cones are curved a bit.

Like its sister the RC-A8, it is a Designerlämpchen, a designer flashlight. http://taschenlampen-tests.de/?p=2557
The shape is at least close to being a longer narrower version of that of the Romisen RC-A8. http://budgetlightforum.com/node/44062 It is bulkier than necessary in a pocket, but it is very comfortable and easy to hold in a hand, even while doing something else with the hand.

There are significant internal differences between the RC-A8 and A6. There is even the architectural difference that an AAA cell fits in the narrow neck, so there is no separate contact board. The A6 has a boost driver. The A8 has a 700 ma. regulating “linear” driver similar to 2 × 7135.

Modification potential

One can hope to improve brightness and/or run time with a driver swap. To maintain throw with the small diameter reflector, an LED swap might be only to a more efficient XR-E, like one out of a POP lite, or to an XP-E2. Or one can use a lower forward voltage LED to put more light out.
The cost of the slim pencil-like shape is the limitations that 2 x AA, except for 1.5 V lithium primaries, doesn’t have a slightly higher voltage replacement like CR123A does, and that 15 mm. is not a lot of space for a boost or buck driver. A zener modded and well cooled BLF SK-68 and two IMR 10440s seems like the only way to get very much current in it.

The driver is soldered to the brass pill. A nice feature but it makes it harder to take apart. There is a mushroom shaped contact button.

The spaces in the pill for the driver and star are each 15 mm. in diameter. The lower part of the pill is 16 mm. and fits in a 16.5 mm. space. So a slightly trimmed 17 mm. driver may fit.

A small star sits between the big LED package and the solid brass pill. There is plenty of heat transfer adhesive.

Surface finish


Art

Flashlight design at its highest point seems to have reached about the point of ancient Greek pottery, without the painting.

The usual criticism of Greek pottery is that it is “mathematical”, in the sense of the simple geometry that was known at that time. An other way to say that is that these lights still resemble, a little, things that could be made on a manual lathe. Either because of his software or his mind set, the designer was not totally free of irrelevant mathematics.

The ideal is still far off. That would be shapes like classical Chinese pottery.


Some places I have learned these things:
http://www.asianart.org, http://www.cityofpaloalto.org/gov/depts/csd/artcenter/, http://www.edpink.com/

Reliability

Out of a total of eight, one of the A6 drivers seemed weak and one RC-A8 has a switch that won’t work with the tail screwed all the way on. The switch is difficult to access, being crimped in at the end of the long tail section.
The light output of my first example was similar to that of an RC-A8, but it drew more current from the 2 x AAA cells than the A8 did from its CR123A. I read 0.55 A at the tail of the A6 and 0.17 now at that of the A8. They both had XR-E LEDs, so the main difference must be in the drivers. Since AAA alkaline cells are cheap and easily available and AAA NiMH cells are easy to charge and good for many cycles, it was usable as is with limited output. A new driver improved the output.
The second RC-A6 that I modified had some space under the star, where it had pulled away from the pill before the thermal silicone adhesive cured:

At the current it drew with alkaline cells, that must not have caused a large decrease of output and would not have shortened the LED life much, but it is a defect and it might matter if the driver and/or cell type had been changed without changing the LED.

Beam shots

UltraOK SK-68 center, A6s on both sides.
Zoomed out

Zoomed in

The cells are, left to right: 2 x Rayovac alkaline AAA, 1 x Excell Alkaline AA, 2 x Eneloop NiMH AAA;
the charge states: 3.05, 1.45, 2.45 volts.
The currents are: 0.5 , 1.1 , 0.7 ampere respectively, comparable in power level and run time.

Conclusion

The LED and possibly the driver are a bit out of date, but it looks and feels so good that I can’t help giving it five stars.


★★★★★style>

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

Edited by: sb56637 on 09/02/2017 - 12:07
Fritz t. Cat
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Modification notes

Driver

I have several #3 zoomies and similar lights like this one. . Some of these have next mode memory, but the drivers seem fairly good otherwise. Most are three mode. I picked an ugly colored one, but I don’t remember where I bought it. I penciled the capacitors of the driver and got rid of the next mode memory. It was the one of the two capacitors that sits near to the coil that did it. These are much cheaper than the Romisens, but they are a recent type so the drivers are more or less up to date. The board is 15 mm. It draws 1.6 A with a single NiMH cell but only 0.9 with two. This makes it brighter with moderate current draw, and the low mode will restore run time when needed.
I removed the old solder with wick and soldered the new driver in for more secure electrical and thermal contact.

LED

I am thinking this will be used mostly at close range, so I am going for total output rather than throw. I chose a Nichia 219C rather than a Cree because the lower forward voltage should make the needed voltage gain smaller, which may make the boost driver more efficient.

The Noctigon XP 16 star had to be filed down by about a mm. in diameter. I enlarged the wire holes of the star and used 24 gauge silicone insulated wire. I flattened the solder blobs that hold the wires to the star with pliers.

Results

At the tail, or rather holding one cell in the air, it draws 0.95 A on high and 0.25 on low. (With new alkalines it draws 0.8 A.)

Compared to an UltraOK SK-68 clone zoomed to about the same spot size, and the SK zoomed out, compared to the Romisen’s spill:
SK on left, RoMiSen on right:

Modification # 2, Driver bought separately, neutral white 219 C

In April 2016, I have two identical seven component boost drivers from Kaidomain and from Ebay. I use the KD one, just because that is the more interesting source. It appears to differ from the driver taken out of a cheap light for the above mod., by having one less transistor.

It has the same component count as the original driver.

The difference may be only a matter of tuning, rather than technical progress.

I use a Nichia 219C LED, 80+ CRI 5000K, From Richard.

Of my two unmodified Romisen RC-A8s, I take the one with lower output. It also has lower input; it draws 0.5 A on the same cells from which the other takes 0.8 A. On these cells, the one modified above draws 1.7 A.

The driver eventually came out of the pill with a combination of solder braid and mechanical force.
I covered the LED with duct tape while I filed a 16 mm. star down to 15 mm. It turned out an interference fit, which I expect to keep the star in contact with the face of the pill, this time. The LED survived the handling and still worked when I took the tape off with mineral spirits.
The holes in the pill for the LED wires are not on opposite sides, so I filed one of the notches in the Noctigon star wider.
The battery was too loose without the button on the bottom of the driver, so I added a clipped bronze spring.

The output seems comparable to that with the driver from the cannibalized # 3 1/2 zoomie, while drawing a bit less current, so buying the driver separately is competitive with buying it in a light.

# 2 Mod. is the neutral white one, # 1 is the warm one. Here they are on new Eneloops.

Currents for the two drivers are:

. . . . . . . . . . . . . . # 3 . . . KD

1 x AAA NiMH . . .1.0 . . .. 0.6
2 x AAA NiMH . . .1.3 . . . .1.2

Both drivers fail to draw more current from the lower voltage source to maintain power. The KD driver draws only 0.6 A from one cell, so it probably has poor output with 1xAA/AAA.

There remained one problem when I got it back together, the KD driver had next mode memory! I took it apart and penciled the cap. That fixed it. Perhaps the capacitor between the controller’s + supply and ground retains enough voltage to keep the memory fresh. The Ebay driver could be alright, as it may be a matter of firmware or depend on component variation, but I will pencil that too in case it is the same. I did not solder it in this time, because I might want to convert to a BLF driver: http://budgetlightforum.com/node/36867.

Modification # 3, Driver from Ebay, neutral white 219C

This driver closely resembles the one from KaiDomain and has less components than the Ebay picture. There may be some in crease in efficiency, but it is no brighter. We need better 15 mm. boost drivers.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

polygon
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This is a Pelikan pen (German) that follows the same sensual lines, although it mates better with the A6 because of it's length. This also came in silver, black and this 2 tone, all satin finished. Wink

ReManG
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Those are shapely lights, is there a link to both? Thanks for the quick review and pictures…

ALL of my links are non-affiliated for your pleasure...

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Fritz t. Cat
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I think I like the pen even better than the light, but nicely shaped pens are a lot commoner than nicely shaped lights. Interesting that the finished are also similar.
The best source I have found is goodluckbuy.com. I think I linked it in the post on the A8. easylightbuy.com and shenzhen-wholesale.com are the same store. They have some, but have proved unreliable in the past and shenzhen-wholesale.com is clumsy to order from because you don’t know the price until they email you about the shipping cost. Maybe it is better not to try to order directly from either site of that company but to email them instead, as most of the things listed are out of stock.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

Fritz t. Cat
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I have added beam shots and generally updated the review, based on new examples.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

ReManG
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Very nice review Fritz! I like the mod of using the #3 zoomie driver, it costs $3 either way to get a driver, so why not use one you know!

ALL of my links are non-affiliated for your pleasure...

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Jerommel
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Hey Fritz,
This is indeed a light i would expect you to like a lot. Smile

Was just looking for a topic about it because i bought one of the last ones from DX at the time (a silver one), and was just looking if there were mods for it, before putting in a Nichia 219B.

But guess what, the 219B on black MCPCB i bought (5 pieces) from Kaidomain, with their odd 14.5mm diameter, fit precisely in the pill of the Romisen RC-A6.
I used the insulation ring that was already there and screwed the head on to the pill and all is good. Smile
Maybe i will swap the driver with one with low and high mode, or maybe not. Smile
The tail switch could use a nicer looking button though, in stead of this black rubber cheap looking and feeling one.

(edit)
…but then i noticed the lens was not clean on the inside, so i tookthe head off and cleaned it, and in stead of the isolation gasket i put in a centring spacer ring, which is thick enough to prevent the reflector from shorting the LED.
Had to sand down the collar though.

….anyway, nice light. Smile

2Q19

daninho
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I like the organic shape, i bet its a pleasure to hold or its a “Handschmeichler” in german. I also like the lack of knurling

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daninho wrote:
I like the organic shape, i bet its a pleasure to hold or its a “Handschmeichler” in german. I also like the lack of knurling
I don’t know what “Schmeichler” means, but mine is really smooth, so it could slip out of your hand when your skin is dry.

…also i have a slight mismatch in anodization colour, the tail is lighter silver than the rest… Sad

2Q19

daninho
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literally translated it means “hand flatterer” but its the same as “a pleasure to hold” i would say. I never had problems with slippery lights i have to say, the lumintop IYP penlight comes without any knurling as well and i like it. The different colors shades of the anodizing it not nice, i hate it i have to say.

Jerommel
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daninho wrote:
literally translated it means “hand flatterer” but its the same as “a pleasure to hold” i would say. I never had problems with slippery lights i have to say, the lumintop IYP penlight comes without any knurling as well and i like it. The different colors shades of the anodizing it not nice, i hate it i have to say.

The difference is not too big, it is still an ‘Augenschmeichler’ Smile

2Q19

greenlight
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Thanks for the essay. We need better lights!

.