Sold/Expired Make your CR123 twisty into a 2-stage CR2 - Interest thread

* NOW CLOSED to new orders * - CR123 twisty - 2-stage CR2

<13-Nov : Minor updates at end of thread>

<edit 9/19/06> NOW CLOSED TO NEW ORDERS. I have no more housings to make more than I have on the list. I am working my way down the list as these still take a lot of my limited time to make. I test each one and add solder to the center post as needed to tune it for short turn from low to high.
Thanks to everyone on the list I will get to you soon.

<edit 8/16/06> Now taking orders from those who posted interest - as my material quantity is limited for now. $14 each with your choice of 10, 15, 20, 24, or 30 ohms. Other ohm ratings by special request.
* See post #63 for positive beta test report *

I have an idea I have been developing to make a simple drop-in puck that would fit in a single cell CR123 twisty along with a CR2 or RCR2 to make any 1x 123 twisty into a two stage CR2 twisty light.

<edit 7/28/06> I will only make less than 10 ohm pieces by special request, but 5 ohm is possible. Most people will want to use these in high power lights, and wattage requirements are lower at higher ohm levels. 5 ohms requires 0.75W. To do this, I will need to use two 0.5W 10ohm resistors, which complicates assembly.

The concept goes like this:
A CR123 is roughly 34mm long by 16mm diameter.
A CR2 is 26.6 to 27mm long by 15.5mm (or less) diameter.
An RCR2 in a CR123 cavity leaves 6.6 to 7mm in length and 16mm diameter to make a disk housing a spring and resistor.
<See picture of mock-up in post #19 below>

In operation:
1) At first contact with the battery and LED PCB, the current has to flow through the resistor for low level.
2) Continue to tighten the battery tube to the head and you compress a leaf spring to ground out to a direct path - bypassing the resistor for full power. Full power of a CR2.

**This may also allow some clicky lights to have two stage. Twist closed a little for low clicky, tighten more to engage high, like the Fenix L1T.**

This general concept has been incorporated in lights for several years and I have seen it in the Orb Raw, FireFly2, McLux (I think) and most recently the Fenix L1T (in a slightly different way). But this is a simple retrofit that you will be able to drop into your favorite Peak, Amilite, Jet-1 CR123, or Fenix Rocket. Even the two stage R123 lights will be able to retrofit for 4 stage output and lower moon modes.

This would allow RCR2's in most CR123 lights that don't currently fit RCR123. It's up to you to make sure the resulting voltage is not too high.

So the question is:
Is anyone interested in getting in on a small build? Should I transform my graph paper designs to CAD? Should I collect parts? Will people buy them? The more interest, the more costs will drop, since I think I will need one part machined at a shop. I estimate cost around $20 and will try to keep it down as low as possible, especially for the initial build.

-Mark

Re: Making CR123 twisties into CR2 2-stage Interest thread

Sounds like a winner to me!:huh:

Re: Making CR123 twisties into CR2 2-stage Interest thread

Thanks Radar1,
I am working on ways to make it simple, cheaper, and to use something I can find and modify (5/8" PVC pipe, flex washers from shock absorbers...) to make just a couple of prototypes. If I make one or two, I'll let you know so you can help test it if you want.
I am still trying to come up with a way to use a CR123, but there is just no room, and it would be light specific if I could do it.

Re: Making CR123 twisties into CR2 2-stage Interest thread

I think this is a great idea. I have no real need for the extra capacity of the 123's and would love the option of a two stage on a light like the Amilight.

Can't wait to see this in my hand.

Re: Making CR123 twisties into CR2 2-stage Interest thread

The CR2 is a great package and on most lights you won't give up much run time. I have several 123 lights that I would like to have a conversion for plus the possible 4 brightness levels as opposed to two. Go for it!

Re: Making CR123 twisties into CR2 2-stage Interest thread

As an update:
My current design direction is to use a Plastic 5/8" (15.875mm) OD tube as found in a hardware store as a cylindrical body. The ID will be bored out to fit internals. The top cap will be a special thin washer (I have 0.15 and 0.2 steel washers to stack up) that are 14mm OD and 4mm ID. I will use an M4 bolt and nut through the 4mm hole as a top contact. I will use the same or similar washer on the bottom as well. These washers will sit on small ledges cut in the end of the plastic tube. These washers are high quality steel that is engineered to flex 2 million times, so fatigue and cracking will never be a problem. Between the washers there will be a 1/4-1/2 Watt resistor of 4-10 ohms soldered between the top and bottom contacts.

The top of the CR2 will sit against the lower washer, current will flow through the resistor to the upper washer and bolt to the contacts in the light. When the twisty is tightened past initial contact, the washers flex to come together to ground out the bolt to the lower washer, bypassing the resistor for full curent flow and brightness.

The issues are cutting the PVC, attaching the washers, and soldering the resistor to the washers during assembly.
I may have to make a special jig or tool to accurately cut the PVC if I try to do it myself in low quantities.
The washers may be glued or heat staked to the PVC. I'm still looking for a better way if possible. <edit> Glue will interfere with flexing, so it's out.
I will probably just route one end of the resistor to the outside to solder on the top of the upper washer or head of the bolt so it can be done last.
The bolt will be cut and ground down to an accurate length to assure a certain amount of flex in the washers will make contact. I am targeting around 90 degrees of additional turn from ON(low) to ON(high).<edit> a thread pitch of less than 0.75mm on my Jet-1 means a less than 0.2mm gap for 90degrees, which is very small, so I will have to shoot for 180 degrees.

Any suggestion on resistors? 5 Ohm? 10 Ohm? I may get a range from 2.2 to 10 for trials. At the moment I plan to have spares, and maybe ship a spare with each assembly.<edit> I will use 2.2 to 10 ohm 1/4 watt for trials since I found 10 ohm 1/4W at Radio Shack today.

I know this may be too much detail to follow here, but I want to make sure anyone that is interested knows what is going on, can follow the process, and make comments/suggestions if they like. All input is welcome.

Mark

Re: Making CR123 twisties into CR2 2-stage Interest thread

I vote for no more than 5-ohm. That's plenty to make an obvious two-level difference.

Re: Making CR123 twisties into CR2 2-stage Interest thread

Sounds interesting, would it work with RCR2s? I have a Peak CPF special that I would like to have as a two stage.

Re: Making CR123 twisties into CR2 2-stage Interest thread

It depends on your light whether RCR2 will work. An RCR2 will give a LITTLE less (I really don't know how much) current than an RCR123 because of lower current capacity, so it MAY work. I will try to compare some RCR123 vrs RCR2 current in some of my lights after I get an order I just placed for four RCR2's today.
On Low, the resistor will make it OK, but on high, bypassing the resistor will put the current directly into your light, there will be nothing in the way of max voltage and current. In the future, I may try to put a second resistor in there for high to enable RCR123 use if I find that some lights just can't take the higher voltage.

*The CPF Special is built for RCR123's, so RCR2's will be NO problem*

I should be able to make versions with several resistance level options (Low) for different lights.

Re: Making CR123 twisties into CR2 2-stage Interest thread

Resistors:
Having done some calculations, I have changed to 1/4 or 1/2 watt resistors since it seems I don't need 1W for single cell twisties. Smaller resistors will fit better, so good news.

Given a 3.7V input from a LI-Ion and assume a 3.3 fV "J" bin Luxeon:
- for 200mA, it looks like a 2.2 ohm 1/4W (or greater) will work
- for 150mA, a 2.7 ohm 1/8W (or greater) will work

Good call Archangel. I'll get a few 2 to 5 ohm 1/4 watt resistors to play with. I will use 1/4W minimum resistors to account for the initial 4.2V from Li-Ions.

I'm not an LED current or electrical specialist, so if anyone sees anything wrong with this, PLEASE let me know.

Re: Making CR123 twisties into CR2 2-stage Interest thread

I could only get 10 ohm 1/4 W resistors at Radio Shack today to start playing with, wich should be OK with a fresh RCR2. I will solder up parts using my washer springs and nut/bolts I got at the hardware store over lunch. Since I have all the electrical components, I can at least test brightness change from hi to low with this setup.

Anyone know where I can get 5/8" OD rigid plastic tube? I went to two hardware stores and only found 1/2" and 3/4". Home Depot is next.
<edit> Home Depot had some PVC tube - sold in ten foot sections for $2. I now have enough PVC to make (10ft x 12in x 25.4mm / 7mm) 435 assemblies not accounting for cutting losses. (maybe 40 pieces after that!)

I have come up with a revised design for a relatively simple machined production part that would combine three parts into one, ease assembly, eliminate one source of potential failure, and make room for a bigger resistor down the middle if needed. It's not feasible for prototyping though. I may send that design to emachineshop.com for a quote. At volume, this assembly should only cost $10-15.

As a teaser, here is an early sketch of the current prototype design direction in cross section:
Photo hosted by Flickr.com
The small circle with an R in it on the right is the cross section of the resistor. The resistor leads are to be soldered to the top and bottom contact plates and bolt. Under pressure, the top and bottom leaf spring plates flex, and the 3mm nut and bolt (nut is there just to hold screw in) touch the bottom spring, bypassing the resistor.
It is 15.875mm outer diameter (across in this photo) and 7mm high. I drew this one-to-one scale to help me design it - that is why the lines are so thick.

As always, feedback, opinions, and offers to buy :naughty: are welcome!

Re: Making CR123 twisties into CR2 2-stage Interest thread

Good call on making them RCR2 compiant:goodjob: This should be really cool!

Re: Making CR123 twisties into CR2 2-stage Interest thread

Remember, they are only RCR2 compliant if the light you put them in can handle up to 4.2V peak, 3.7V continuous.

That said (for the lawyers), I did a trial last night with an unprotected RCR2 at 3.7V (not fresh of charger) and a 10 ohm, 1/4W resistor. Shorting just the RCR2 to my Amilite Neo T3 caused brightness about the same level as the 3.0V regulated RCR123 I usually have in it, but using the resistor put out about one quarter to one third the brightness, about what I would consider perfect for a low level. I was not able to measure current, I will have to do that this weekend.
So I consider this test successful:rock:, except that I'm not sure I'm comfortable with the resistor warming up. Not bad, but I will look into 1/2W resistors just in case.

Next step is to try and cut some body pieces from my PVC tubing. I may have to use a lathe to get the accuracy I want. If I can't get access to a lathe this weekend, I will try to hand cut some parts, but it may be difficult and ugly even if it does work. But I see a run of prototypes within two weeks if all goes as planned. The soldering step is a tiny bit of an unknown because I've never soldered to this type of hardened spring steel, ..hell, I've only ever soldered a couple of times ever, so it's all an unknown to me. That is my only other possible delay besides getting different ohm resistors for specific requests. I haven't even seen 4.6 ~5.7 ohm resistors in stores yet, so I may have to mail order them.

Radar1, Roboholic, Archangel, and Minkling will all get first (and cheapest) crack at prototypes (first run actually). Given my result above, what resistors do you want in your samples?

Re: Making CR123 twisties into CR2 2-stage Interest thread

Sorry, I have to pull out of this one. Trading off my RCR2s.

Re: Making CR123 twisties into CR2 2-stage Interest thread

Is that measured 1/4-1/3 brightness, or just what it seems? I have a 5ohm in my NGBB500 miniMag and it's almost exactly 1/4 the brightness measured with my meter. I'm not sure a direct comparison can be made though since that running ~2/3 the voltage. If that's actual brightness than yeah, 10ohm works. If not, i guess 10ohm still works if that's as low as you can find. Once you start taking about "seems", there no way to know if both of our seems are the same.

Re: Making CR123 twisties into CR2 2-stage Interest thread

I'm in for TWO if possible, one for my Amilite and one for my Peak CPF special, This is FANTASTIC, how did I miss thiss!!! Great Job!!!

:buddies:

Re: Making CR123 twisties into CR2 2-stage Interest thread

Archangel said:

Is that measured 1/4-1/3 brightness, or just what it seems?... If that's actual brightness than yeah, 10ohm works. If not, i guess 10ohm still works if that's as low as you can find. Once you start taking about "seems", there no way to know if both of our seems are the same.

Click to expand...

That brightness level was just my impression. I don't have any way to measure lumens, lux, or candles. We will probably have to go off eventual beamshots.
I will still try to find some lower ohm resistors to try. I will test two 10 ohm resistors in parallel to act like 5 ohm and take beamshots of all three (0, 5, and 10 ohm) if I can clamp them up. I have been holding them together by hand.

I found brass bolts and nuts to use for the upper contact since they should be lower resistance than steel. Did you know steel only has 12% the conductivity of silver? Copper has 97% and brass is part copper, part zinc, so I hope it is more conductive than the steel bolts I have.

Re: Making CR123 twisties into CR2 2-stage Interest thread

I'd like to have about 1/3 - 1/2 of original brightness. You make the call on the ohms. Looks like this is taking off!:goodjob:

Re: Making CR123 twisties into CR2 2-stage Interest thread

Did some current tests this weekend on my Q3. My numbers (measured on the 20 Amp scale on my multimeter) seem high, but the relative numbers seem to agree with the observed (estimated) brightness.
Full power = 820 (mA?)
~Half brightness from 5 ohms (two 10 ohm in parallel) = 350 mA
~1/5 brightness from 10 ohms = 250 mA

Half brightness will therefore give ~three times the run time, but 1/5 brightness is a little dim, so I will most likely shoot for between 5 and 10 ohms, again giving options for orders. Get what you want!

I also did a mock-up showing the size on a CR2 next to a CR123.
picture hosted by Flickr.com
The screw head on top will be ground down smooth to be much nicer to the positive contact on your light.

Re: Making CR123 twisties into CR2 2-stage Interest thread

Looking good blind! I might be interested in one for my Jet1.