AMC7135 Specs Inside UPDATE

Mr Happy · Mar 24, 2008

Re: AMC7135 Specs Inside

TorchBoy said:
No - it's a linear regulator - and yes respectively.

Very well, I bow to common parlance. Though I don't see why the term "buck" has to be confined only to step-down regulators that use switching technology

TorchBoy · Mar 24, 2008

Re: AMC7135 Specs Inside

Yeah, I don't know why that is. It certainly caused a bit of confusion for me before I figured out what people meant by it.

Supernam · Mar 25, 2008

Re: AMC7135 Specs Inside

TorchBoy said:
Supernam, if you're going with alkalines I'd definitely recommend 4 instead of 3. Their voltage really doesn't hold up and most of their life is with a lower voltage than would do the job if you only had 3.

With NiMH, it would depend what the Vf of your LED is and when you wanted the thing to drop out of regulation. Drewfus' test above showed his LED needed 4V for the board to stay in regulation, so 4 NiMH cells would probably work better in that situation, and drop out of regulation at a loaded 1V per cell. Note though that the board might get quite hot when the NiMH cells are freshly charged.

The more I look at the data, the more I wonder what WAS this board designed for? One LiIon would mean that there would be no regulation for the most part. 2 CR123's is too much. 3 Nimh's would present the same problem as 1 LiIon. It seems as though the only way to go with this board is to use 4 NiMH's. I think 3 D sized Alkalines would work fairly well, at least with the 1050mAh board. 4 would bring you to at least 6v which will run the board pretty darn hot when you're using new batteries.

I was planning to use this with a SSC P4 with a Vf around 3.3 in 3D Nimh host, but I'm going to just kill my wallet with a buck/boost GD1000 instead (about $25 shipped for 1!). Perhaps this board will be better with a 4C or 4 SubC mag.

Drewfus2101 · Mar 25, 2008

Re: AMC7135 Specs Inside

Supernam said:
The more I look at the data, the more I wonder what WAS this board designed for? One LiIon would mean that there would be no regulation for the most part. 2 CR123's is too much. 3 Nimh's would present the same problem as 1 LiIon. It seems as though the only way to go with this board is to use 4 NiMH's. I think 3 D sized Alkalines would work fairly well, at least with the 1050mAh board. 4 would bring you to at least 6v which will run the board pretty darn hot when you're using new batteries.

I was planning to use this with a SSC P4 with a Vf around 3.3 in 3D Nimh host, but I'm going to just kill my wallet with a buck/boost GD1000 instead (about $25 shipped for 1!). Perhaps this board will be better with a 4C or 4 SubC mag.

I bought these specifically for modding Mags with alkalines and P4s. Like you said, 3 alkalines are pretty perfect. The 700mA setting is slightly lower than you really want, but still plenty bright and works great for 3 C batteries. And the 1050mA setting works well for 3 D batteries that can handle that current draw better than the C size batteries.

mike2g · Mar 25, 2008

Re: AMC7135 Specs Inside

Supernam said:
The more I look at the data, the more I wonder what WAS this board designed for? One LiIon would mean that there would be no regulation for the most part. 2 CR123's is too much. 3 Nimh's would present the same problem as 1 LiIon. It seems as though the only way to go with this board is to use 4 NiMH's. I think 3 D sized Alkalines would work fairly well, at least with the 1050mAh board. 4 would bring you to at least 6v which will run the board pretty darn hot when you're using new batteries.

I was planning to use this with a SSC P4 with a Vf around 3.3 in 3D Nimh host, but I'm going to just kill my wallet with a buck/boost GD1000 instead (about $25 shipped for 1!). Perhaps this board will be better with a 4C or 4 SubC mag.

I completely agree. Efficiency and regulation occur in two separate parts of the voltage curve, with only a small overlapping area. If you want efficiency greater than 90%, then you have to stay below 4.2V. If you want, regulation you need to stay above 4V. This leaves a 0.2V window to get good regulation and efficiency.

If you are willing to have an efficiency down to 80% the voltage must only stay above 4.6V/4.8V for the 1050ma/1400ma version respectively. Regulation still requires 4V so the window for regulation and efficiency is now 0.6V/0.8V (1050ma/1400ma).

From the battery perspective however, this is difficult to achieve. Li-ions will start at 4.2V and quickly drop below 4V and out of regulation. Regarding alkaline D batteries, it seems that the voltage drop is roughly linear from 1.4V to 0.8V, resulting in a 0.6V change. However because there are multiple cells the change is now 1.8V for 3 cells, and 2.4V for 4 cells. Both of these are much larger than the 0.8V window allowable for 80% efficiency.

Nimh may be the best solution however for it's ability to maintain voltage up to the bitter end. At the 1A draw rate for AA, the discharge is primarily between about 1.35V to 1.15V giving a change of 0.2V. This change is 0.6V and 0.8V for 3 and 4 cells respectively. This range seems reasonable for the 80% efficiency minimum and the best compromise from the available battery choices.

The only optimism I have left for this board is in the coming SSC P4 test with the lower Vf. Hopefully the regulated range will increase. Thanks Drewfus2101 for doing the meticulous testing! :thumbsup:

freedom2000 · Mar 25, 2008

Re: AMC7135 Specs Inside

Drewfus2101 said:
1050mA version:

I definitely love a good boost/buck convertor more than these, but these things are not bad little boards. I thought others could benefit from these numbers.

Hi Drewfus2101,

Many thanks for this nice technical review. (I have just bought such a driver, and you already helped me a lot).

You mentionned however that you prefer boost drivers...
Would you have a recommendation for me to find a good (and cheap) driver to drive a Q5 Cree led at 1A with one or two Nimh ?

My intention is to mod this flashlight, which has curerntly a rather inefficient driver see here

Again, thanks for your help
JP

TorchBoy · Mar 26, 2008

Re: AMC7135 Specs Inside

Drewfus2101 said:
And the 1050mA setting works well for 3 D batteries...

Why?

(That Energizer Max doesn't do too well compared to the others.)

Within a handful of minutes the cells are down to 1.4V, and by the time they hit 1.2V there's, what? 75-80% of the life left. And even 3x1.2 V would be enough only if the Vf of the LED is <=3.4V. Yeah, they exist in quite a few P4s, but I don't think many Q5s. From 1.2V onward, even a 3.4 Vf LED would be out of regulation.

I still say three alkaline cells are not suited for this driver (unless you want to just use the top 20% of each cell's capacity).

mike2g, your point of voltage difference is very good. I'll still say 4 alkaline cells will work quite nicely, though, with a qualifier or two. Because of the way alkaline cells discharge, the board when used with the LED tested above would be in the higher efficiency area (median would be 84.5%) for four times longer than it would be in the low efficiency area. So for efficiency, it would work nicely. If regulation is your goal, however, you'll have to use a low Vf LED to have it stay in regulation until 0.8 V per cell, and that would push the median efficiency down (to ~75%), which I'd still be happy with for efficiency as well. I don't deny you might have trouble finding the right LED though.

mike2g said:
Efficiency and regulation occur in two separate parts of the voltage curve, with only a small overlapping area.

That's a contradiction. I suppose the efficiency area isn't quite a subset of the regulated area, so you could say the areas are in different, but not separate, places.

mike2g said:
Thanks Drewfus2101 for doing the meticulous testing!

It's a great test, and both very interesting and very useful, but meticulous probably means something other than what you intend. You can't have 1.24 A in and 1.28 A out with a linear regulator - no disrespect intended to you Drewfus.

(Actually, one definition for meticulous I found is "ridiculously obsessed with extreme minutiae" - which would be me posting this.

)

freedom2000 said:
Would you have a recommendation for me to find a good (and cheap) driver to drive a Q5 Cree led at 1A with one or two Nimh ?

freedom2000, I don't think such a driver exists, if $20 (for a GD1000) doesn't come into your idea of cheap. Have you seen the driver list?

Drewfus2101 · Mar 26, 2008

Re: AMC7135 Specs Inside

freedom2000 said:
Would you have a recommendation for me to find a good (and cheap) driver to drive a Q5 Cree led at 1A with one or two Nimh ?

I wish I did. I've bought the only two single mode boost drivers that DX sells but have only had time to test one. I'm trying to do the same thing.

This is the one that seems better, but I havn't had a chance to test it. I'll post the results when I get a chance:
http://www.dealextreme.com/details.dx/sku.4735

Here is the other one. You can see my post at the bottom of the page. These boards are useless as boost boards. Maybe they are just mislabeled.
http://www.dealextreme.com/details.dx/sku.4382

Drewfus2101 · Mar 26, 2008

Re: AMC7135 Specs Inside

TorchBoy said:
Why?

(That Energizer Max doesn't do too well compared to the others.)

Within a handful of minutes the cells are down to 1.4V, and by the time they hit 1.2V there's, what? 75-80% of the life left. And even 3x1.2 V would be enough only if the Vf of the LED is <=3.4V. Yeah, they exist in quite a few P4s, but I don't think many Q5s. From 1.2V onward, even a 3.4 Vf LED would be out of regulation.

I still say three alkaline cells are not suited for this driver (unless you want to just use the top 20% of each cell's capacity).

mike2g, your point of voltage difference is very good. I'll still say 4 alkaline cells will work quite nicely, though, with a qualifier or two. Because of the way alkaline cells discharge, the board when used with the LED tested above would be in the higher efficiency area (median would be 84.5%) for four times longer than it would be in the low efficiency area. So for efficiency, it would work nicely. If regulation is your goal, however, you'll have to use a low Vf LED to have it stay in regulation until 0.8 V per cell, and that would push the median efficiency down (to ~75%), which I'd still be happy with for efficiency as well. I don't deny you might have trouble finding the right LED though.

That's a contradiction. I suppose the efficiency area isn't quite a subset of the regulated area, so you could say the areas are in different, but not separate, places.

It's a great test, and both very interesting and very useful, but meticulous probably means something other than what you intend. You can't have 1.24 A in and 1.28 A out with a linear regulator - no disrespect intended to you Drewfus.

(Actually, one definition for meticulous I found is "ridiculously obsessed with extreme minutiae" - which would be me posting this. )

freedom2000, I don't think such a driver exists, if $20 (for a GD1000) doesn't come into your idea of cheap. Have you seen the driver list?

To your first question about using the 1050mA with 3 D alkalines, I should have said that was my choice OVER direct driver or resistors. As I said, DD with resistors was always a headache. These are better, but definitely not perfect.

For the Mag that I made for a friend, I used a SSC P4 and the 700mA version with 3 D alkalines. It was that or a 1 ohm resistor.

Drewfus2101 · Mar 27, 2008

**UPDATE**

Following the suggestions, I tried a few different things. First I found a SSC Z-Power P4 emitter and tested it:

So it has a more lower Vf than a Cree Q5 does.

Then I hooked it to the 1050mA version of the AMC7135 and re-ran the normal test the exact same way as before. Next I took out the diodes and soldered in a leg from a resistor in place and re-ran the same test. Both tables are below followed by the graphs.

Removing the diodes didn't seem to make much of any difference at all in the efficiency:

freedom2000 · Mar 27, 2008

Re: AMC7135 Specs Inside

Drewfus2101 said:
I wish I did. I've bought the only two single mode boost drivers that DX sells but have only had time to test one. I'm trying to do the same thing.

This is the one that seems better, but I havn't had a chance to test it. I'll post the results when I get a chance:
http://www.dealextreme.com/details.dx/sku.4735

Here is the other one. You can see my post at the bottom of the page. These boards are useless as boost boards. Maybe they are just mislabeled.
http://www.dealextreme.com/details.dx/sku.4382

Thanks !

The first one is backordered ...

So I have ordered this one (it has good reviews... I couldn't resist :thinking

What seems to be nice is that it has a pot to trigger the output level (left side of the pic)

JP

TorchBoy · Mar 27, 2008

This test just gets better and better. You the man! :bow:

Those output current figures are sometimes still a bit high compared to the input current (as much as 4.4%). What can be done about that?

It looks like taking out the diodes has not made a significant difference for the voltage range tested. That supports what I said in post 17, but even your SSC P4 doesn't have a low enough Vf at 1 amp to know for sure if it will make any difference at even lower voltages. But what you've basically done is Mythbusted the idea for any except possibly the very lowest Vf LEDs, or low VF LEDs run at lower current. :clap:

Could you the test with just one AMC7135 on the SSC? That would show what happens to regulation at a slightly lower voltage.

Of course, using the diodes will mean the board could be used at up to 6.6V in.

CampingLED · Mar 28, 2008

Thanks again for your great info/review. On the morning of your first post I purchased a 3D to use for a quad Cree Q5 mod. The intention was to use these drivers. Now I know I need another solution. I should have gone for the 4D instead, but like the size and feel of the 3D.

Drewfus2101 · Mar 28, 2008

TorchBoy said:
This test just gets better and better. You the man! :bow:

Those output current figures are sometimes still a bit high compared to the input current (as much as 4.4%). What can be done about that?

It looks like taking out the diodes has not made a significant difference for the voltage range tested. That supports what I said in post 17, but even your SSC P4 doesn't have a low enough Vf at 1 amp to know for sure if it will make any difference at even lower voltages. But what you've basically done is Mythbusted the idea for any except possibly the very lowest Vf LEDs, or low VF LEDs run at lower current. Could you the test with just one AMC7135 on the SSC? That would show what happens to regulation at a slightly lower voltage.

Of course, using the diodes will mean the board could be used at up to 6.6V in.

I think the current figures are the same but that my readings methods add some error in there. The current in reading is coming straight off my power supply. The current out in a multimeter with the leads spliced into the wiring of a setup that I made to test emitters and driver boards. So I feel that the current is the same and the error is coming from my method of reading, although there is no other way of reading. I did try and use the largest guage wire that I could find, but couldn't use the thickest stuff in my entire setup. I'll try and snap some pics when I get a chance.

I can re-run the test at the 350mA level. It will be early next week before I get a chance, but thats no problem. I'll start a new thread at that time. I might even see what happens at 6.6V.

Drewfus2101 · Mar 28, 2008

CampingLED said:
Thanks again for your great info/review. On the morning of your first post I purchased a 3D to use for a quad Cree Q5 mod. The intention was to use these drivers. Now I know I need another solution. I should have gone for the 4D instead, but like the size and feel of the 3D.

Glad I could help. Thats the whole point after all. To help educate myself and whoever else will listen and hopefully help other people make the right choice in they're projects.

TorchBoy · Mar 29, 2008

I guess the only ways to get around that current measuring problem would be to repeat the test run with all voltages measuring the current in with your multimeter - lot more work - or get a second meter.

I don't think there's much need to test the high voltage limit of the poor thing, although knowing a bit more about failure modes might be useful. Your call on destructive testing.

Supernam · Mar 31, 2008

Awesome update!

***Off topic plug. If anyone would be willing to trade some of the 1400mA versions for 1050mA version, please PM me. I need 2, but can trade up to 6. (Don't feel like ordering another set of 10).

TorchBoy · Mar 31, 2008

Supernam, why don't you just pull a couple of AMC7135s off a board and put an extra one on a couple of boards? Or piggyback them and just have one board with lots and lots.

Edit: Not unlike this doubled board from KD, which arrived in just the last week.

TorchBoy · Apr 9, 2008

Drewfus2101 said:
I can re-run the test at the 350mA level. It will be early next week before I get a chance, but thats no problem. I'll start a new thread at that time. I might even see what happens at 6.6V.

Have you had a chance to run that test yet? (I don't think I've missed any new threads about it.)

Drewfus2101 · Apr 9, 2008

TorchBoy said:
Have you had a chance to run that test yet? (I don't think I've missed any new threads about it.)

No not yet. I'm hoping tonight or tomorrow night I will get a chance. I'll add the info in this thread when I do.

AMC7135 Specs Inside **UPDATE**

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