modified Romisen RC-T6

[hanachan]

Hi, I have been modifying the Romisen RC-T6 to the underwater light.

My light first received from DX was defective; normaly it powers 2->4->6 LEDs.My light powered 2->another 2->another 2Leds. So i exchanged it with new one. But the new one had the same defect. As the exchange at DX took a lot of time(1 month), I decided to repair it by myself. I found its defect occurred at lower voltage of battery. But with full charged battery it initially powered 6 LEDs but shortly did 6->4 and 4->2 LEDs. I thought the diodes connected to the switch were bad. so I exchanged them resulting no improvement. I knew the similar report that this light does not work well under 8 volts at another thread in the CPF. In this light the driver used is PT4115; this IC works above 8 volts!! To power 6 LEDs results the down of voltage of the battery and fails in lighting. I guess many defective RC-T6 might be sold...

Anyway I started the modification of Romisen RC-T6 to UW light with such the problem.

I ususally use the UW light with the UW camera. The flashlight is too long for me. So I cut it in two.

and removed the diodes and connected wires directly to the driver

and sealed the front and rear of the light part and front of the battery part
and made the waterproof switch. It works only 1 mode (all 6 Leds powered).

I tested it in the washstand. The initial voltage was 4.21Vx2(18650x2).

Reslut: Initially for 20 min it powered 6 LEDs(top fig.). for next 40 min 4 LEDs(inside fig.) and after then it powered only 2 LEDs(bottom fig.). I turned off the light two hours after beginning of test and immediately turned on it again but no light. The final voltage was 3.6Vx2.

The direct wire connection attained a little improvent. But I can enjoy the good brightness(6 LEDs) only about 20 min.

Next I will make the new switch which enables 2 mode(2 or 6LEDs). Usually I use it with 2LEDs and when I wish I will power 6 LEDs. But I think the basic solution is achieved only by the increasing the input voltage such as 18650x3 used. I must make the new battery box....
Anyone has a good idea?

To be cont.

 

[hanachan]

Re: modify Romisen RC-T6

Hi, today I carried out the 2nd lighting test of the modified RC-T6.

I made the new switch with Double-Pole/Double-Throw toggle switch,
low(power 2 LEDs)-off-high(power 6 LEDs).

and reformed the front(top in fig.) of the battery part.

The test was carried out as that the low mode (2LEDs) for 10 min and the high(6 LEDs) for 5 min altenatively for 2 hours.

The initial voltage was 4.16Vx2(not fully charged).
Six LEDs lightning was succeeded for 4 times i.e. after 1 hour from the begin of the test. Total time was 20 min; this is the same as at previos test. Then 4 LEDs lightning 2 times and only 2 LEDs lightning in high mode after 90min.

left:at start of test(6 LEDs lightning) right:at end of test(2 LEDs)

The final voltage was 3.7Vx2. After the test it was possible to power two LEDs.
No water invasion was observed.

I think two mode is usefull. Though I could do 2 dives sparing the battery,
I have no reserve battery. So still I have to make the battery case for 18650x3..

 

[hanachan]

Hi, I carried out the 3rd test of my modified RC-T6 yesterday.
It may be somewhat difficult to make the battery case for 18650x3.
So I made a case for single 18650.

and inserted it between the battery case and the switch in series.

As the glue of the new battery case had not dry, the test was carried out with only the light part underwater.

left:at start(6LED lightning) right:after 2 hours of test.
All the 6 LEDs were continuously luminous (very bright!) about for 2 hours. And then it abruptly ceased lightning.
Reswithching OFF and ON enabed lightning with 6 LEDs agian
but the 3rd trial of relightning failed. After then it did not light with 2 or 6LEDs.

The initial voltage of 18650 was 4.21 or 4.22 Volt. The final voltage was 3.45, 3.42 and 0 Volt respectively.
The recovery voltage of the 0 Volt battery was 3.32 Volt.

Theoretically it can power light with 2 LEDs for 6 hours.
This result satisfied me. Next I will use it under the sea.

 

[csshih]

nice work!

better get those underwater sea shots!

 

[hanachan]

Thank you attention.
Tomorrow I'll go diving and take a beam shot underwater unless flooded.

 

[hanachan]

Hi, I dived and took the beamshots of the modified RC-T6.
I have learned the difficulty of taking the beamshots underwater.
I thought it is easier to take the fish photos...

I dived with G10+DIY semifisheye lens+4 modify flashlights including the RC-T6. One of them in the BC.
I have been testing my waterproof method of the flashlight.

The light supporter was broken at the boat to the diving point.
So I had to take a photo having the light in my left hand.
Fortunately it was cloudy and the visibility was not so bad. We searched the dark area and took the photos.

This photo taken by the buddy's camera by my side at 23m depth.

SP-320:SS=1/80, F=2.8, ISO=100, no flash
The distance between the fish and the light was about 1m.
That between the fish and the camera was about 2m.

The distance between a sea anemone and the light was about 20cm.

A: taken by the buddy's camera by my side.
SP320:SS=1/80, F=2.8, ISO=100, no flash
B: taken by my camera(G10)
G10:SS=1/40, F=3.5, ISO=80, no flash

another 2 samples at 10m depth

the distance between the objects and the light was about 50cm.

No water invasion was obsereved in all 4 flashlights.

It was not so brighter underwater against my expectation.
My buddy's HID 20W light was brighter. But it was too much brighter as a focus light.
I think this modified RC-T6 is bright considering its cost(about 70USD).

The beamshots show that the spill of the light was not so effective to light the object. The thrower type of light may be usefull underwater.

Although how long this light works well is still the issue, my project of modifying RC-T6 ends.
Next I would like to make a brighter light than this as cheap & easy as possible.
Thank you.