my first headlamp "construct"

As I anounced in my very first post, it shall be simple.

So here it is my first « construct », I call it a construct as it is what it is: Quick, dirty, but simple.

Thanks to all at CPF for ideas, issues & diverse turn arounds, sold parts, fun.
Special thanks to ursuspeleus and his ACETOLED for the main idea

knowhow: soldering, sawing, screwing, glueing

construction time: 1 week (yes, the epoxy had to harden too)

oh yes, ehhhrrr... sorry for metric units, I´m from the old continent...

parts:
1x SSC-P7
1x AMC7135 350 mA driver
1x AMC7135 2800 mA driver
1x controler "NanoDim" (or any other that allows dimming with a trimpot)
glass fiber epoxy board
1x on/off switch
1x 3x4 rotating switch
1x trimpot 10k
2 compound epoxy glue
non-conductive thermal epoxy
4x4 cm square tubing, 2-3 mm strength

reason for choices:
SSC-P7 – nuts idea, next will be Cree MC-E (4 individual dies)
controller: I wanted a construction that can be dimmed with a pot.
rotating switch: in mode low it will consume a maximum of 350 mA/h
on/off switch: a necessity to reset the controller when it freaks out (once in overdrive, no way to reset it than switching completely off)
all the rest: just a matter of commodity to get into the stuff whilest learning.

I´m sorry, the pics from the assemby are gone, but the finished product is below.

1st round
- Starting with cutting a 6 cm piece of 4x4 cm rectangular tubing. (2mm strength)
- 2x 2,5mm boreholes for screwing the P7 to the tubing (3mm steel screw in 2,5mm alu hole keeps tight)
- 2x 3mm boreholes for the P7 connection wires
- Mounting the P7, with thermal epoxy, then screwed (if you like to screw it)

2nd round
- Cutting acrylic glas, 3 pieces 4x4 cm, 2 having a bore hole fitting the SSC-P7 into.
- Epoxy glueing the acrylic glas to a sandwich, smoothing the sides, sandpapering the top,
- Epoxy glueing the acryl sandwitch above the P7

3rd round
- cutting glass fiber board : twice 4x4 cm & twice x 3,6x3,6cm

4th round
- sandwiching one 4x4 and one 3,6x3,6 cm board, adjusting it the smaller fits into the tubing, the larger covering the tubing (do not yet glue it onto the tubing!!!)
- drilling a hole for the rotating switch
- fit the rotating switch onto the drilled board (take care it does fit into the tubing)
- you may use additional epoxy glue for water tightening the parts
- call this side board A

5th round
- sandwiching one 4x4 and one 3,6x3,6 cm board, adjusting it the smaller fits into the tubing, the larger covering the tubing (do not yet glue it onto the tubing!!!)
- drilling 3 holes: for the trimpot, the on/off switch and cable
- fit the trimpot, the on/off switch and cable onto the drilled board (take care it does fir into the tubing)
- you may use additional epoxy glue for water tightening the parts
- call this side board B

6th round:
- glue with non conductive thermal epoxy the 2 prewired AMC boards and the controller onto a 2x6 cm aluminium bit (or epoxy board)
- do soldering between the bords
- glue the resulting board into the 4x4 aluminium tubing, I kept it tight with clamps

7th round:
- solder the wires from boards onto the rotating switch (side board A)
- solder the wires from boards/switch to LED
- fit sideboard A to side of 4x4 tube (everything fits?)
- glue side board A to side of 4x4 tube

8th round:
- solder wires to trimpot, on/off toggle, battery cable (side board B)
- do check with connected batteries if everything is OK
- fit sideboard B to side of 4x4 tube (everything fits?)
- glue side board B to side of 4x4 tube

9th round:
Finding a solution to fix the construct to helmet or anything else:
I did it with o-rings.

It´s splashproof, not watertight. That´s next step.

run times:
high mode @ 2800mA, not dimmed: around 3h 46min on 2800mA, then I stopped although still shining.
low mode @ 350mA (moon dim), still OK after 26 hours

batteries 4x Eneloop in series (ok, it should be just 3, but I was to lazy for adapting a battery holder)

plan:

face:

right:

left:

top:

ON

oh yes, brightness:
its bright, its a P7

"beam" spreading more than 180°, the layered acrylic glass reflecting a part of the light to up to around 200-210° on the sides and around 250° above head :huh:

I don not understand the runtime??

Wich cells you are using??

Regards.

4 AA 1,2V Eneloop in series (actually)

runtime with circuit switched to the 2800mA driver, undimmed = 3 hours 46 minutes (meaning floodlight for at least that time)
runtime with circuit switched to the 350mA driver, dimmed to nearly minimum = 36 hours moon mode so far (still shining this morning)

one thing I forgot to mention, I bridged the diodes on the AMC7135 boards.
This giving me around 0,4 more volts that would have been "lost" through the diode drop voltage.
To protect the circuit, I put a red LED with a resistor anti-paralell to the whole circuit.
Meaning, if I insert/connect the batteries the wrong way, current will flow the inversed way and the red LED will flash and warn me about, but the circuit will not .
This was for me the best solution for a situation where I have to change batteries in complete darkness (what already happened once) and where I need a visual feedback to know the origin of the eventual problem. No light would mean that at least one battery is Ok and at least one battery is inversed.

Wow, full marks for detail, and for using metric measurements. Got a link for that nanodim controller?

cyclopsed said:

rotating switch: in mode low it will consume a maximum of 350 mA/h

Click to expand...

Um, mA would make more sense.

cyclopsed said:

4 AA 1,2V Eneloop in series (actually)

runtime with circuit switched to the 2800mA driver, undimmed = 3 hours 46 minutes (meaning floodlight for at least that time)
runtime with circuit switched to the 350mA driver, dimmed to nearly minimum = 36 hours moon mode so far (still shining this morning)

Click to expand...

An Eneloop cell has a nominal 2 Ah, and four in series will have 2 Ah also. Drawing 2.8 A will give you less than an hour runtime. (SilverFox's testing indicates the battery would have less than 1.8 Ah at that draw, so it would be less than 40 minutes.)

Of course, your driver will drop out of regulation gracefully, so you probably will not notice you're not running at full power any more. What voltage were your cells at by the end of that test? What current was actually being drawn from them?

You're probably better off staying with four cells. I made a 3x XP-G (each with 3x AMC7135) headlamp recently that just wouldn't run in regulation with only three. There was too much voltage sag and resistance losses.

cyclopsed said:

one thing I forgot to mention, I bridged the diodes on the AMC7135 boards.
This giving me around 0,4 more volts that would have been "lost" through the diode drop voltage.
To protect the circuit, I put a red LED with a resistor anti-paralell to the whole circuit.

Click to expand...

Only if it's a Schottky diode, which those AMC7135 drivers don't come with. 0.6-0.65 V would be more like it for silicon diodes, which makes it even more attractive to do.

cyclopsed said:

To protect the circuit, I put a red LED with a resistor anti-paralell to the whole circuit.
Meaning, if I insert/connect the batteries the wrong way, current will flow the inversed way and the red LED will flash and warn me about, but the circuit will not .

Click to expand...

That sounds quite clever, but wouldn't it still be putting a voltage across the driver the wrong way around? If the driver can survive your reaction time until you turn it off that's a great idea. Doesn't your battery holder only connect the cells to the holder terminals one way around? Is it the Petzl Duo battery holder?

Hi torchboy

Nanodim, Ebay Germany item no. 140372362739
There is a link on the item side to the data sheet, unfortunately... its in German.
Most is self explanating, if need is, I can do a kind of translation.
If a problem exists to draw the datasheet, I can email it.

Um, yes for all your points...

Yes, mA

Yes for the 2000 mA if Eneloops are in series (mine are).
But time indications are true...
3 hours 46 in high mode when I turned off.
P7 still running in moon mode when I went home an hour ago. Making around 40 hours+

I did not do any mesurements... shame is.

Yes 3 cells are better... for known reasons to be found here at CPF and in datasheets.
However, I had the feeling that the driver went out of regulation with 3 cells when barebone testing driver+controller+P7.
I misinterpreted this as not having enough voltage and driver going to direct drive. Therefore I added an other cell
You gave me an other reason, which, for unobvious reasons, I did not dare to consider :s

Diode: yep, I was departing with guestimated minimum.

Antiparalell diode: No... maybe... yes... I was departing that the P7 working like a diode would block, thus current (or most of it) will go through red LED for the short time I have to switch off. I might be wrong... remembering now reversed voltage on the data sheet of the P7... thinking...

No, its not the duo holder, its apart, for reasons of separated circuits in case of failure, low bats, leakage,.... Used holder is a (an other) construct I still had in the cellar... actually fixed to the back of the duo holder with velcro until a better solution is found (has to be found).

cyclopsed said:

Yes for the 2000 mA if Eneloops are in series (mine are).
But time indications are true...
3 hours 46 in high mode when I turned off.
P7 still running in moon mode when I went home an hour ago. Making around 40 hours+

I did not do any mesurements... shame is.

Click to expand...

I strongly suggest you make some measurements ASAP. By doing so you will find out what your LED is actually doing, and you may be able to avoid some long term problems. For example, using four cells in series, one could go flat and be reverse charged by the others while those three still have enough voltage to drive your LED in moon mode. Running it for 40+ hours without knowing what state each of the cells are in seems like a great way to guarantee this happens. :green:

cyclopsed said:

Yes 3 cells are better... for known reasons to be found here at CPF and in datasheets.

Click to expand...

Better for what? Yes, it's better for efficiency if you have enough voltage to run in regulation. It's not better for staying in regulation at high currents because you're far more likely to run out of volts. How many volts does your P7 want at 2.8 A?

As for known reasons, how about these? They basically result from V = I*R.
- Eneloops at 2.8 A will show a higher voltage drop under load than they will at 350 mA. Have you seen SilverFox's testing?
- Voltage drops from even small resistances in your setup will be higher at 2.8 A than they will at 350 mA. On my high mode of 3 A there's a definite measurable drop even just between the back and the front of my caving helmet, and that's with a good thick length of speaker wire. Every battery terminal contact will also add resistance, which will therefore have a voltage drop across it.

A thought - there's actually no point in you using a P7 with a 2.8 A driver if you're happy with a much lower (and unregulated) current, which you will be getting after so many hours running. I say go for the power your headlamp should be able to deliver!

cyclopsed said:

However, I had the feeling that the driver went out of regulation with 3 cells when barebone testing driver+controller+P7.
I misinterpreted this as not having enough voltage and driver going to direct drive. Therefore I added an other cell

Click to expand...

I think you made the right choice, but it shows why you need to make measurements. Without knowing what's actually happening you're making decisions in the dark.

cyclopsed said:

Antiparalell diode: No... maybe... yes... I was departing that the P7 working like a diode would block, thus current (or most of it) will go through red LED for the short time I have to switch off. I might be wrong... remembering now reversed voltage on the data sheet of the P7... thinking...

Click to expand...

The Vdd pin of an AMC7135 will still be connected to the positive side of the LED it's driving. Normally it would have the extra polarity protection diode in between. It might get a lot more complicated with the extra controller you have. :shrug:

With the 7135 and voltage-protection diodes, really it comes down to what voltage is needed to turn the chip on vs. what supply voltage is needed to give meaningful output with the LED chosen.

The 7135 datasheet reckons 2.7V is the minimum recommended supply voltage (though the actual minimum may be lower in practice).
If the LED Vf + 7135 dropout voltage was >~3.3V, the presence or absence of the diode might not make much difference to normal operation.

With a 4-cell NiMH battery, by the time the combined voltage has dropped to ~3.3V, it seems likely that at least one of the cells will be close to empty, but also, unless the cells are very mismatched, with luck the weakest cell wouldn't be entirely flat and ending up reverse-charged.

Having a cutoff (or at least a reduction in drain) at something like 3.3V doesn't seem like a bad idea.

It looks like the Nanodim controller wants at least 3.5 V, which three cells under heavy load at the back of the helmet could easily drop under - at least by the time they're partly used. I have no idea what it does under 3.5 V though. The web site http://www.ledtreiber.de/ keeps coming up with a complaint about "overLIB", so I'm not making much progress in finding out what the exact specs are.

TorchBoy said:

I strongly suggest you make some measurements ASAP... :shrug:

Click to expand...

I disconnected the batts yesterday eve.

Going to reopen Pandora's epoxy box during the weekend to do measurements.
Also taking a stabilized power supply to have a closer look on behaviour with lower voltages on the whole circuitry.

Results will be available by next monday, partial results maybe earlier, there are enough questions that deserve an answer.

TorchBoy, uk_caver, or anyone else, if you are interested in mesurements on particular testpoints, just ask.

edit:
TorchBoy, going to send you the downloadable pdf manual if you like, PM me a mail adress.
First readings: all 4 batts still have each 1,3V (precisely) yep, thinking it would be less, my first reaction was: 8-I

cyclopsed said:

Also taking a stabilized power supply to have a closer look on behaviour with lower voltages on the whole circuitry.

Click to expand...

Ooh, that will be good.

cyclopsed said:

edit:
TorchBoy, going to send you the downloadable pdf manual if you like, PM me a mail adress.

Click to expand...

But is it in German?

TorchBoy said:

But is it in German?

Click to expand...

yes...

Thanks for the offer, but I think I'll pass. My German's not so hot.

TorchBoy,
I didn't find any the time to do mesurements this weekend, as I had to visit familly to a hospital quite far away.
But what I did just now during my lunch time to change thoughts, was to do a translation of the Nano-Dim manual.
If you still are interested, PM me.
I think that you are the one who did best job to establish a driver data base, so it shall be your benefit to get at least a quite good (maybe not best) translation to know at least what we are going to talk about later.
Paul

Sure, go ahead and send your translated datasheet to me (email link is in the footnotes of the Driver List). Thanks very much!

Great floodlight! Maybe you shuold try a smooth reflector on your next mod?

TorchBoy said:

Sure, go ahead ... !

Click to expand...

on the way

COAST said:

Great floodlight! Maybe you shuold try a smooth reflector on your next mod?

Click to expand...

floodlight was intented

cyclopsed said:

floodlight was intented

Click to expand...

Ohhhhh ok. Understood .

cyclopsed said:

on the way

Click to expand...

Thanks cyclopsed. I'll look it over and add it to the list when I get a chance.