Parallel wiring of shining beam 2.5A driver

[TorchBoy]

One type has 2 diodes, another type has only 1 diode and the last type has surface mount resistors. The boards with the surface mount resistors are the newest boards that I've purchased, so that's probably what they all come with now.

You'll find they're surface mount diodes, not resistors. All those little packages look the same, but in this case the arrowhead on them shows which way around the diode works.

There are different models of AMC7135 chip, with outputs that vary from ~300 mA to ~380 mA. It may be that the bottom number has something to do with that. I don't know.

Thanks for the extra pics and explanations.

 

[ti-force]

You'll find they're surface mount diodes, not resistors. All those little packages look the same, but in this case the arrowhead on them shows which way around the diode works.

There are different models of AMC7135 chip, without outputs that vary from ~300 mA to ~380 mA. It may be that the bottom number has something to do with that. I don't know.

Thanks for the extra pics and explanations.

Thanks for the info, I didn't know they made surface mount diodes. Like you said, they're all so small and look about the same:thumbsup:.


BTW, thanks for putting that led driver list together; it's a pile of information.

 

[ti-force]

Anyone looking for information on drivers should go to CPF member TorchBoys site at

http://www.videofoundry.co.nz/ianman/laboratory/research/driverlist.php

There's a HUGE amount of information here and a VERY good write up at the bottom of the page about AMC7135 drivers. I recommend to anyone who's reading this to try and learn about the AMC7135 drivers, go to the above link and scroll all the way to the botton for the 7135 info:twothumbs. Of course, check out all the other info on the way down.

 

[TorchBoy]

FWIW there's a quicklink/jump link to it too: http://www.videofoundry.co.nz/ianman/laboratory/research/driverlist.php#AMC7135 (and then click to expand).

 

[Fulgeo]

That is indeed the spec of the chip, but did you (and others) notice the "Reverse-polarity protection prevents wrongly installed batteries from damaging the circuit" claim? That means there's a diode on the Vdd pin which will drop ~0.6 V, so the driver as a whole will actually have a 3.3-6.6 V range. As far as heat goes the thermal protection will likely cut in well under 6.6 V.

Hey TorchBoy as a rule I have always removed the diode(s) from my non PWM AMC7135 boards. I wanted to say that if you push these AMC7135 boards above 6.0 volts you are really asking for trouble. They will generate allot of heat and besides the efficiency at 6.0 volts is close to 60% where as at 4.0 volts it is 90%+. I usually use them with 3 D sized NiMHs. I have been playing with a stacked AMC7135 board circuit with 4 x NiMHs (4.8v - 5.6v) to drive a SST-90. When you suggested in your post that by removing the diode that upper range was 6.6 volts I was concerned that someone will try and drive these boards with two LiFePO4 lithium cells in series. Just wanted to reiterate drive these boards with 3 to 4 NiMH cells in series or 3.7 volt lithium cells in parallel. Happy Mods!

 

[TorchBoy]

Thanks Fulgeo. I'll clearly state (again) that whatever voltage the board as a whole (not just the driver chips) might be able to cope with, the AMC7135 chips might not be able to cope with the heat from dropping all those extra volts.

However, there are ways to reduce the power dissipated by the AMC7135s, such as placing a resistor between battery positive and LED positive. All the excess volts still need to be dropped, but if some of the power gets dissipated by the resistor instead of the AMC7135s then the AMC7135s will run a little cooler. That does nothing to help driver efficiency, but that's not always a concern.

BTW, I did NOT say (in post 11) that removing the diode will give an upper working limit of 6.6 V. It's including the diode that gives that extra 0.6 V.

 

[Fulgeo]

BTW, I did NOT say (in post 11) that removing the diode will give an upper working limit of 6.6 V. It's including the diode that gives that extra 0.6 V.

My apologies TorchBoy I misinterpreted what you said. What happened is when I read "an upper working limit of 6.6 volts" I know from playing with the AMC7135 boards they are at their best efficiency, reliability and heat well under 6.0 volts. I have built 14 mods to date using the AMC7135 boards. I run them usually with 3 D NiMH cells and they work great. I have run them with 4 NiMH cells and they work but they do generate some heat. I have a 3 D SSC P7 mod driven at 2.8 amps by two stacked 1.4 amp AMC7135 boards that I have over 100 hours on. It is very reliable so far. I used it to read by.

TorchBoy have you built a mod using the AMC7135 boards well heatsinked at 6.0 volts or above for duration? I have test benched it and I get so much heat that I do not trust it enough for a build. I figure it will be unreliable. I have not proven this thou. Also I want to say that I ask this question with no accusatory air. I have respect for you and appreciate your input.

 

[TorchBoy]

I know from playing with the AMC7135 boards they are at their best efficiency, reliability and heat well under 6.0 volts.

All true.

TorchBoy have you built a mod using the AMC7135 boards well heatsinked at 6.0 volts or above for duration?

Nope! Like you I normally use 3x AA (or AAA) NiMH, since there's really no point to go with higher voltage with the Vf of the LEDs I use them with. All I'd get is extra heat. So I've never pushed an AMC7135 to its limit to see if I can get it to slide off the board.

For 4x AA NiMH there are buck boards that suit very nicely, and their better efficiency at those voltages is preferred for my caving uses, what with runtime and all.

 

[Mettee]

Torchboy,

My first time looking at your site, looks good...lots of good info there.

Tiforce,

If you need any help with spacers or anything let me know I can blast some out for you, or even make the entire thing for you. I have made a few so it would not be much trouble.

Drew

 

[ti-force]

Tiforce,

If you need any help with spacers or anything let me know I can blast some out for you, or even make the entire thing for you. I have made a few so it would not be much trouble.

Drew

Drew,

Thank you very much for the kind offer. I may need to call on you if I can't get this thing done. What material do you normally use for the non conductive spacers?

Casey

 

[Mettee]

Delrin, with a brass, copper, or Al plug, Then I either solder to the copper or I use a small set screw to hold the wire. If I was making this pack I would use hobby noodle wire in as heavy a gauge as I could.

I have been trying to figure out the best way to load batteries if the individual person has to remove them for charging, but I am still in the same place. I use a triton most of the time so I just keep them loaded, but some people may not be able to.

 

[420light]

FWIW there's a quicklink/jump link to it too: http://www.videofoundry.co.nz/ianman/laboratory/research/driverlist.php#AMC7135 (and then click to expand).

That is very helpful. I saved your chart into my Favorites. Thanks.

 

[TorchBoy]

I'm glad you folk find it useful (or at least interesting). I just remembered that I made a short path as well. http://www.videofoundry.co.nz/driverlist

 

[ti-force]

Delrin, with a brass, copper, or Al plug, Then I either solder to the copper or I use a small set screw to hold the wire. If I was making this pack I would use hobby noodle wire in as heavy a gauge as I could.

I have been trying to figure out the best way to load batteries if the individual person has to remove them for charging, but I am still in the same place. I use a triton most of the time so I just keep them loaded, but some people may not be able to.

PM sent.

 

[wildstar87]

FYI, if you look at the spec sheet, the absolute max voltage of the AMC7135 chip is 7v I believe, the only reason I know this, is I am running a multimode slave setup, running off a 5-cell NI-MH battery pack. It's from a previous bicycle light system, and it's still working, so I decided to use it. I have been able to run this light for a good length of time. HOWEVER, they chips are definitely well heatsinked, otherwise there is no way they would take the heat. The body of the light, which they are transferring the heat into does get quite warm, so I know that they are putting off a lot of heat, and unlike Alkaline, they will stay at 6v or above for most of the runtime, so I had to be sure that they had a way to get rid of the heat.

When the battery pack finally dies, I will just run it with 4 cells instead, but this allows me to use a perfectly good bicycle battery setup with the modded light.

 

[SteveoMiami]

Ti-Force or anyone that knows... I saw how you stacked 7135 chips directly on top of eachother and that worked.. Are there any disadvantages doing it that way instead of stacking the entire boards? It looks like it would save a lot of room.

 

[ti-force]

Ti-Force or anyone that knows... I saw how you stacked 7135 chips directly on top of eachother and that worked.. Are there any disadvantages doing it that way instead of stacking the entire boards? It looks like it would save a lot of room.

The only disadvantage I can think of is heat dissipation, and I'm not sure that would actually be a problem unless your input voltage is considerably higher than the led's voltage forward. The higher the input voltage is over vf, the less efficient the driver becomes because it has to burn off the excess voltage.

 

[ti-force]

BTW, if anyone's interested in changing a Shiningbeam 1.4A, 3- mode driver into a single mode driver, all you need to do is remove the ATMEL chip, then solder a jumper wire and you will have a 1.4A, single mode driver :thumbsup::

Here's a picture: