# AMC7135 based boards?



## One Pivot (Nov 20, 2009)

Ive seen a few of these. They seem to have extremely high efficiency, with some people claiming 90-95%. They dont seem to have too many features or anything, but they're dirt cheap!

Not a real amp blaster, with the highest hitting about 1400ma, but thats fine for some projects. Any input on these types of boards?

ex: http://www.dealextreme.com/p/amc7135-1400ma-regulated-circuit-board-for-diy-flashlights-20-pack-3178
http://www.dealextreme.com/p/amc7135-1050ma-regulated-circuit-board-for-diy-flashlights-10-pack-1885


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## manokaiser (Jun 30, 2008)

I've been using them for years! As they can be paralleled you can use as many as you like to get the output you wish. 
Check this version also: http://www.kaidomain.com/ProductDetails.aspx?ProductId=10995
It uses 8 of them for 2,800 mA output and has configurable groups of modes for lower output too. Perfect for single MCEs and XM-Ls!
They are acceptably efficient through the voltage range of a single lithium cell. They get very high efficiency if you closely match input voltage to the driven LED forward voltage.
Pretty tough too as they are protected internally.
Check the datasheet: http://www.micro-bridge.com/data/ADD/AMC7135.pdf


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## mattthemuppet (Jul 16, 2004)

I think they're fine for simple cheap builds, but I'd personally invest a bit more in the driver given how long I spend making (and using) my lights. They're designed for torches/ flashlights, so you'll need a clicky switch, and they don't have any kind of voltage warning, so you'll need either protected cells or a pack with a protection PCB. They also don't have any thermal monitoring, which may become an issue at higher current levels and LED counts.

I bought a 350mA version of that to make a rear light for my commuter bike - can't argue with a complete light for <$10 - but for my front lights, off-road or commuter, I only use Taskled drivers.


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## One Pivot (Nov 20, 2009)

They're so crazy cheap, even if they're terrible its not much of a waste! I need a few bright tail lights too. I can build one for all my bikes, and have a few to mod up for a few headlamps too, for less than the cost of a taskled driver.


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## mattthemuppet (Jul 16, 2004)

that's fair enough - it's your money and time, I'm just giving you my point of view. It takes me a while to build a light, so I want it to last and I'd rather pay the extra for the features, reliability and support of a Taskled driver. However, plenty of people make decent lights out of cheap drivers. Don't forget though, that you should get protected cells or PCBs for your battery packs otherwise you'll risk overdischarging your battery and ruining it.


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## One Pivot (Nov 20, 2009)

Ive been using 18650 flashlights for headlamps for a few years now, so im pretty stocked up on protected cells. They've served me fine in all honestly, I just like to tinker.


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## manokaiser (Jun 30, 2008)

*Rear Light*

I have build a rear light with those which has a unique function! It is light on continually and pulsed brighter 3-4 times per second. I will post a diagram of the circuit but basically is very simple: I have added a resistor and a blinky led to the input. Resistor and blinky are in series connected between Supply Voltage and Ground, blinky attached to Vs. Then driver input (Vdd) is connected at their intersection. Calculate the resistor based on the blinky Vf and the Voltage of your Source.


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## mfj197 (Jan 28, 2011)

manokaiser said:


> I have build a rear light with those which has a unique function! It is light on continually and pulsed brighter 3-4 times per second. I will post a diagram of the circuit but basically is very simple: I have added a resistor and a blinky led to the input. Resistor and blinky are in series connected between Supply Voltage and Ground, blinky attached to Vs. Then driver input (Vdd) is connected at their intersection. Calculate the resistor based on the blinky Vf and the Voltage of your Source.


Sounds good - that is the one thing that I'd like that I don't think is in the TaskLED interface. I'd be interested to see your circuit.


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## El34 (Jan 11, 2009)

See my build site link below.
AMC7135 based boards are all I use for nice simple P7 bike light builds.

Use one board for 1400ma 1/2 power low.
Put two in parallel for 2800 ma high
Use a simple switch to switch from high to low

http://www.el34world.com/Misc/bike/BikesLights1.htm


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## manokaiser (Jun 30, 2008)

*Rear Light*

So here it is the schematic.
I've used a Red Power Led, an optic defuser of 120 degrees and this circuit, all enclosed in a humble metal bottle cover.
I have also used a small RAM heatsink at the back of the LED star but you can check for yourself to see if it's needed. It depends on the housing you use, but it should hardly get any warm at all.
I am not sure about the resistor value but you can play with it and see how it affects output. As a starting point let's say you have a 3V blinky @ 30mA. If your source is 3,7 you want to drop 0,7 V across it, so R=V/I = 0,7V/0,03A=23Ω.
It's a nice, bright and noticable rear light, if you manage to make it let me know what you think!


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## spence77 (May 14, 2011)

manokaiser said:


> So here it is the schematic.
> I've used a Red Power Led, an optic defuser of 120 degrees and this circuit, all enclosed in a humble metal bottle cover.
> I have also used a small RAM heatsink at the back of the LED star but you can check for yourself to see if it's needed. It depends on the housing you use, but it should hardly get any warm at all.
> I am not sure about the resistor value but you can play with it and see how it affects output. As a starting point let's say you have a 3V blinky @ 30mA. If your source is 3,7 you want to drop 0,7 V across it, so R=V/I = 0,7V/0,03A=23Ω.
> It's a nice, bright and noticable rear light, if you manage to make it let me know what you think!


this is exactly what i've been looking for. I assume the transitor icon is the AMC7135 (is it just a transitor?). I've spent hours looking around the internet for such a thing.

How long does it run for? What battery are you using? Would it be ok with 3 x NiMH AA's as I don't have an Lithum cells, they scare me a little, plus I've already got supplies of AA and AAA Nihm and a fairly good charger.

thanks for the ideas


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## manokaiser (Jun 30, 2008)

spence77 said:


> this is exactly what i've been looking for. I assume the transitor icon is the AMC7135 (is it just a transitor?). I've spent hours looking around the internet for such a thing.
> 
> How long does it run for? What battery are you using? Would it be ok with 3 x NiMH AA's as I don't have an Lithum cells, they scare me a little, plus I've already got supplies of AA and AAA Nihm and a fairly good charger.
> 
> thanks for the ideas


Yeap! Transistor Icon is AMC7135, I had no better way to picture it, though it is not just a transistor, it's an IC, a Linear Constant Current Sink. Its fine to use 3xNiMH, I am using a single Li cell. The circuit with the resistor I use pulls ~ 40 mA continually and pulses the Power Led with higher current when the blinky jumps in. It lasts for ages, I haven't bother to calculate. Let's say 2500mAh / 40mA = 62.5 h, you get an idea.


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## HuffyPuffy (Jun 9, 2008)

This is a cool idea to use the blinky LED to control the 7135. 

These are really cool drivers, I used several to power a P7 several years ago with a multimode board from DX, coupled with some 1A boards, ended up with so many modes it was almost useless. They are limited to driving a single LED though since their input voltage range does not go high enough to drive 2 in series.


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## spence77 (May 14, 2011)

manokaiser said:


> So here it is the schematic.
> I've used a Red Power Led, an optic defuser of 120 degrees and this circuit, all enclosed in a humble metal bottle cover.
> I have also used a small RAM heatsink at the back of the LED star but you can check for yourself to see if it's needed. It depends on the housing you use, but it should hardly get any warm at all.
> I am not sure about the resistor value but you can play with it and see how it affects output. As a starting point let's say you have a 3V blinky @ 30mA. If your source is 3,7 you want to drop 0,7 V across it, so R=V/I = 0,7V/0,03A=23Ω.
> It's a nice, bright and noticable rear light, if you manage to make it let me know what you think!


Got all the components and been playing around. I have something going but not exactly sure if this is correct.

The Cree XPG flashes but only if the resistor is removed, but its not off then on it's on (dull or 1/2) then pulses full on with the flashing LED. Using 3 x AA so 3.6v the Flashing LED is a 3mm 3.3v 20ma so I calculated about 15Ohm resistor but with this in place only the flashing LED flashes, NO Power LED at all. I increased the resistor up to 45Ohm but no change.

I've added a 1uF capacitor from positive to ground as per the AMC7135 recommended usage but with or without this I have the same behaviour, just a fraction of a second to start up and fraction of a second fade out when battery is connected/disconnected.

Is this the behaviour I should be seeing and will running it without the resistor cause damage to anything.

Thanks
Spence

Here is the Blinking LED
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=360320012646&ssPageName=STRK:MEWNX:IT


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## manokaiser (Jun 30, 2008)

> The Cree XPG flashes but only if the resistor is removed, but its not off then on it's on (dull or 1/2) then pulses full on with the flashing LED.


Actually this is the desired behavior! Try a lower the resistor to see how it effects the dim and full on brightness.
Let's calculate it again: 
*R = V / I *
You have* 3.6 V* Source, *3.3V Led @ 20mA*,
we need to drop 3.6 - 3.3 = *0.3 Volts*
*R=0.3V / 0.020Α = 15 Ω*

I have everything enclosed and sealed inside so it's an inconvenience to open and check the circuit again.
As long as I remember I 've been praying with the Blinky and Resistor for a while before I get to the final Low On - Blinking High mode. I remember I had tried the configuration as in the schematic as well as the reverse: Attach the resistor on Top + and the blinky to ground. Somehow I had the Completely Off - Blinking On mode, if that's what you prefer.
I prefer the first though I was trying to get the later. It came out by luck actually. 

Reading from the link you bought the blinky:

Forward Voltage Min 2.8V , Typical 3.3V, Max 4V.
That means you can get away with no resistor at all, or considering the worst case scenario, you should count for the fully charged battery voltage (4.2V?) instead of the typical 3.6V. But I'd use that 15 Ω resistor anyway, it should be safe in any case!.


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## spence77 (May 14, 2011)

manokaiser said:


> Actually this is the desired behavior! Try a lower the resistor to see how it effects the dim and full on brightness.


thanks for info, I don't mind the way it's working, the only thing I did notice is that as the battery discharges the full on flash gets duller and dulller until it really doesn't look like it's flashing anymore.

Anyway I'm thinking I'll up it to 4 x AA anyway as 3 is really a pain to recharge so I'll do up a new board with possible 2 x 7135 chips and a solid on 750ma mode plus a 350ma mode that flashes.

Just on the heat, I had the circuit running for 6+ hours without any heatsink on the power led (except the 20mm star board/heatsink it came mounted on) and it didn't even get warm to touch so i'd guess it was only about body temp.


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## manokaiser (Jun 30, 2008)

> the only thing I did notice is that as the battery discharges the full on flash gets duller and dulller until it really doesn't look like it's flashing anymore


My Guess is that's probably because of the discharge characteristic of NiMH, which is an almost linear down slope.
The voltage is lowering as it discharges leaving little room for the extra current the blinky feeds to the Driver. I use a single LiIon cell that has a more flat discharge rate line so I haven't notice this. I think I have to keep an eye on it though cause if this is the case for LiIon too it would give a nice indication of battery getting low. Neat!! 
Perhaps someone with more knowledge of electronics could explain us precisely how this circuit functions this way.


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## rlouder (Jun 26, 2007)

I built a single, then a double xml using single 2.8A 7135 last winter. They've been great for me. Check my pics. Search for "poor man" setup for using a single 7135 chip with more than one LED.


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## Alinvanc (Nov 15, 2011)

is anyone still responding to this thread ?
If so, I'm looking to make on of these, can I just tap off one of the unused Vdd and ground pads and to connect the blinky and resisitor ? Since only one of the 7135 IC pads are being used for a 350mAh driver, the unused pads are in the circuit anyway. 

Does anyone have an actual picture of the modded 7135 ?

One other thing, I have both the 350mAg and the 1050mAh 7135 drivers from Kaidoman. 
When I run XPG P6 LED's, the difference in visible light output is negligable, but the heat output is significant, the 350 is not warm at all, the 1050 is not hot, but warmer than the 350. Does anyone else notice this ?


Thanks


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## emu26 (Jun 23, 2008)

Alinvanc said:


> is anyone still responding to this thread ?
> If so, I'm looking to make on of these, can I just tap off one of the unused Vdd and ground pads and to connect the blinky and resisitor ? Since only one of the 7135 IC pads are being used for a 350mAh driver, the unused pads are in the circuit anyway.
> 
> Does anyone have an actual picture of the modded 7135 ?
> ...


I would have to say that there is a problem with the 1050mA board, not because of the heat but because the light difference should be more than "negligible". You won't get 3 times the output but you should notice the difference.


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## manokaiser (Jun 30, 2008)

Have a look @ the threads below, you'll probably get your answers and some pictures too.
http://forums.mtbr.com/lights-diy-do-yourself/flashing-725900.html
http://forums.mtbr.com/lights-diy-do-yourself/flashing-rear-light-768767.html


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## Alinvanc (Nov 15, 2011)

Thanks Mano, 

The only issue with these drivers is the battery voltage that these drivers can handle. I would rather use 7.4v battery packs, 4.4 Ah, to get longer run times. What are your voltage/Ah battery configurations that you use ?

thanks for your input


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## mattthemuppet (Jul 16, 2004)

just use the same no. of cells in parallel and you'll get pretty much the same run time. Instead of 7.4V 4.4Ah it'll be 3.7V 8.8Ah. Both store exactly the same amount of energy - 32.6Wh.


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## Alinvanc (Nov 15, 2011)

thanks Matt, I new at all this, doing a mod on a dual Marwi Viewpoint housing. Instead of buying the parts form E34, I'm sourcing and putting together myself. 

Do you put your own battery packs together ? I'm looking at buying the Ultrafire 18650 3.7v 4000mAh batteries, putting two in a case and wiring those to my lights. Cost will be less and $20 and I should have plenty of run time. Does anyone know about the Ultrafire, Trustfire and Soshine brands of Li-Ion batteries ? they have similar specs but different prices. 

Thanks for your input guys.


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## Vancbiker (May 25, 2005)

Alinvanc said:


> I'm looking at buying the Ultrafire 18650 3.7v 4000mAh batteries, putting two in a case and wiring those to my lights. Cost will be less and $20 and I should have plenty of run time.


When you are figuring out your runtime, cut the 4000mAh value at least in half. Those cells are grossly overrated. See this link to CPF.

Ultrafire 18650 4000 mah


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## Ofroad'bent (Jul 10, 2010)

Alinvanc said:


> thanks Matt, I new at all this, doing a mod on a dual Marwi Viewpoint housing. Instead of buying the parts form E34, I'm sourcing and putting together myself.
> 
> Do you put your own battery packs together ? I'm looking at buying the Ultrafire 18650 3.7v 4000mAh batteries, putting two in a case and wiring those to my lights. Cost will be less and $20 and I should have plenty of run time. Does anyone know about the Ultrafire, Trustfire and Soshine brands of Li-Ion batteries ? they have similar specs but different prices.
> 
> Thanks for your input guys.


I have to say, EL34's service is very good.


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## manokaiser (Jun 30, 2008)

Vancbiker is right, you should be able to get ~ 2400 mAh out of the best batteries sold in DX. Max Voltage of 7135 is 6 Volts but you will have to stay close to your Led forward Voltage to keep loses down. One Cell is ideal for one Led, should you need to use two Cells you could consider using two Led in series.


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## mattthemuppet (Jul 16, 2004)

Alinvanc said:


> thanks Matt, I new at all this, doing a mod on a dual Marwi Viewpoint housing. Instead of buying the parts form E34, I'm sourcing and putting together myself.
> 
> Do you put your own battery packs together ? I'm looking at buying the Ultrafire 18650 3.7v 4000mAh batteries, putting two in a case and wiring those to my lights. Cost will be less and $20 and I should have plenty of run time. Does anyone know about the Ultrafire, Trustfire and Soshine brands of Li-Ion batteries ? they have similar specs but different prices.
> 
> Thanks for your input guys.


you're welcome. If you're going to do a Marwi mod, I'd seriously consider getting at least the alu slug from El34, it'll make your life considerably easier.

I do build my own batteries. I have used *fire cells before, and they're fine for lower current lights (XP-G, XP-E etc), but I found that they're a bit hit or miss with high current XM-L lights, as they can't always provide enough current. I've since built all my packs and those for others with Panasonic cells. They're more expensive but they're considerably better. The highest capacity ones are pricey, but you can get the lower capacity ones (~2500mAh) for $7-8 and are easily worth the premium over Chinese cells.

For a twin XM-L Marwi light, I'd run a driver in each head then run both heads off a single 4x 18650 pack in 1S4P set up (3.7V). With decent cells you're looking at ~10Ah and ~ 1 3/4h run time with both lights on full. I really wouldn't waste your time with the cheap Chinese cells, they're going to cause you all kinds of problems.


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## Alinvanc (Nov 15, 2011)

Thanks Guys, 

Ofroad - Thanks for the suggestion, I've communicated with EL34 before, he does provide timely info and I would assume his service is very good. I am of the bent to "find my own path" with a little help from my friends (thanks again guys). I enjoy the journey of trying to make things myself. 

Matt - Thanks for the info. I have already made my slugs from solid 1 1/4" aluminum rod. A lot of sawing on my scroll saw and filing. They do the job and seem to be effectively transferring the heat from the LED to the body.

I will definately use the more expensive batteries. How do you connect them together as I gather that soldering is a hazardous endeavour. 

I am going to run a separate driver for each light. One light will have a H/L, the other will have a flash / H. I do a lot of city night riding so visibility to cars is my primary consideration. With both lights on high, that is sufficient for trail riding. I'm using XPG's with the 1050mAh 7135 drivers.

Thanks again guys


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## mattthemuppet (Jul 16, 2004)

well, if you're just running XP-Gs at 1A each then you can happily use the cheaper *fire cells and save yourself some money. I built a 4P pack for a friend using some old Ultrafire 2500 cells (real capacity 2250mAh) which runs his single XM-L light at 3A just fine. 4 of those will cost you ~$15 from DX, instead of ~$30 for Sanyos or Panasonics. I think Of'roadbent has used the Trustfire flames (2500mAh?), which are protected cells, to good effect.

For making battery packs you have 2 options. Holders, like those off Digikey or eBay, or soldering the cells together (which is neither hard nor dangerous if you're even remotely sensible).


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## Ofroad'bent (Jul 10, 2010)

For an easier battery build, I've had good luck with an eBay vendor now called Allbattery 2012.
He sells decent Sanyo cells already connected and protected, in any config you want. You just need to waterproof them. True 2500 mAh each, not the bogus numbers we see.

Images in this thread: http://forums.mtbr.com/lights-diy-do-yourself/easy2led-build-custom-back-cap-772150.html

Otherwise, Ktronic sells a good protection board which you can solder to unprotected cells. I've soldered directly to the contacts on cells, and also used protected holders or soldered protection boards with unprotected holders.


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## mattthemuppet (Jul 16, 2004)

I've just ordered one of Charge/Discharge Protective Circuit Board for Rechargeable Li-Ion Batteries (17.4mm*1.9mm) - Worldwide Free Shipping - DX
to see if I can use it to re-purpose some currently idle unprotected 18650s for a head torch. Seems to have decent reviews and it's cheap as chips


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## Alinvanc (Nov 15, 2011)

I just bought the following from all battery

charger
All-Battery.com: TLP-2000 Universal Smart Charger for Li-Ion/Polymer battery Pack (3.7V - 14.8V, 1-4 cells)
battery pack
All-Battery.com: Tenergy Li-Ion 18650 3.7V 10400mAh Rechargeable Battery w/ PCB

the battery pack is a deal if it holds up, 3.7v 10,400mAh including PCB protection for $21.99 !!! Wow, if the batts are decent, this is a good deal


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## Vancbiker (May 25, 2005)

Alinvanc said:


> I just bought the following from all battery
> 
> charger
> All-Battery.com: TLP-2000 Universal Smart Charger for Li-Ion/Polymer battery Pack (3.7V - 14.8V, 1-4 cells)
> ...


Seems pretty darn good for the battery. The only drawback some may have with that charger would be that it will take a long time to recharge this battery.


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## Alinvanc (Nov 15, 2011)

I made a mistake, I bought the 1.0A charger, so charging will still take a while, but half as long as the 500mAh charger.

All-Battery.com: Tenergy Universal Smart Charger for 3.7-14.8V 1-4 Cell 1A Li-ion/LIPO Battery Pack
We'll see about the battery,,,,


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## El34 (Jan 11, 2009)

I use 1 amp chargers. Don't have much of a problem with them.

Typical sequence is,

Go to a ride
Come home
Put battery pack on charger
Go to sleep
Wake up in morning
Battery is charged

It may take 6 hours if the pack gets really drained, but I don't care, I am asleep.


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