Adjustable 10A linear LED driver - New and Improved!

[flashfiend]

Sorry if this is an incorrect question to ask, but what is the minimum input voltage of this driver? Would this driver work on one sst-90 with 2 Li-Ions in parallel?

[Delphinus]

5.76V off the charger. I never attempted to do a long run since the light gets so hot after a minute, it's just for show and was aware of that. I'll get the low mode working soon when I find a good 2 pole rocker that will fit.

Today I will continue my tests, I believe that large part of the hot comes from the circuit, why don’t you use only 3 cells and have someone to machine you a fake one or even better use the extra space for a bigger circuit dissipater.

For the 2 mode I use a very simple solution, one inverter reed, magnet off LOW magnet on HI

http://www.conrad-international.com/...-int&pi=503642

http://www.produktinfo.conrad.com/da..._DT_5W_1WE.pdf

[Aircraft800]

Today I will continue my tests, I believe that large part of the hot comes from the circuit, why don’t you use only 3 cells and have someone to machine you a fake one or even better use the extra space for a bigger circuit dissipater.

For the 2 mode I use a very simple solution, one inverter reed, magnet off LOW magnet on HI

http://www.conrad-international.com/...-int&pi=503642

http://www.produktinfo.conrad.com/da..._DT_5W_1WE.pdf

I've tried with 3 X 4500mAh NiMH "C" cells, and there was no way to discharge them fast enough to get the wanted 10A result, the battery voltage sag was too much. I did not try 3 X NiMH "D" cells, but I believe the results would be similar, too much sag.

I like the switch idea, I'll have to do some research on it, I'm not familiar with how they work. Thanks for the help!!

EDIT: If you wouldn't mind, can you point me in the right direction on how to implement such a switch, or a simply a schematic? Maybe I can mount the magnet in the head, and a simple twist would switch from low to high?

[Delphinus]

EDIT: If you wouldn't mind, can you point me in the right direction on how to implement such a switch, or a simply a schematic? Maybe I can mount the magnet in the head, and a simple twist would switch from low to high?

You connect the side that has only one terminal to C and the other two
terminals to L and H, and test if you got full power change the L and H terminals, with a small magnet put it close to the C terminal of the reed to get full power.

Did you use the lamp switch in series with the batteries or in series with the C terminal and the H? I don't know the lamp but probably it won’t handle 10A it's safer to use it between the C terminal and L and H this way will you should remove the batteries to prevent a full discharge of them but will save the switch.

My English it not good probably someone else could help you better.

[DIWdiver]

I've tried with 3 X 4500mAh NiMH "C" cells, and there was no way to discharge them fast enough to get the wanted 10A result, the battery voltage sag was too much. I did not try 3 X NiMH "D" cells, but I believe the results would be similar, too much sag.

I like the switch idea, I'll have to do some research on it, I'm not familiar with how they work. Thanks for the help!!

EDIT: If you wouldn't mind, can you point me in the right direction on how to implement such a switch, or a simply a schematic? Maybe I can mount the magnet in the head, and a simple twist would switch from low to high?

Reed switches, including the ones suggested by Delphinus, are wired just like any other switch. The only difference is that they are switched by a magnet instead of your finger pushing on something. His suggestions on how to wire it are correct.

D

[Delphinus]

Reed switches, including the ones suggested by Delphinus, are wired just like any other switch. The only difference is that they are switched by a magnet instead of your finger pushing on something. His suggestions on how to wire it are correct.

D

DIWdiver thank you very much for this circuit it works very well and if we don't need 2 power modes it has a double function power limiting and power switch.

I'm working in my video lamp and finally decided on the batteries, I choosed LI-PO since your circuit only takes 0.25V it works very well.

When I have more data I will post it.

[DIWdiver]

Sorry if this is an incorrect question to ask, but what is the minimum input voltage of this driver? Would this driver work on one sst-90 with 2 Li-Ions in parallel?

It is a good question to ask. Unfortunately, the answer is not simple.

For this discussion I will talk about a 10A driver that has been adjusted to give 9A. Some info on other driver models is at the end of the post.

The driver works by placing a variable resistor between the battery and the LED. When the input voltage is too high for the LED, the driver makes the resistance high, so the current will be 9A. As the battery is discharged, the driver constantly adjusts the resistance, to keep the current always at 9A. At this point the driver is "in regulation".

But the resistance can only go as low as 0.03 ohms. At some voltage, this resistance will be too high to get 9A to the LED, and the current will begin to drop. At this point the driver is "out of regulation" and it will look like a 0.03 ohm resistor all the time, as long as the input voltage is at least 3.0V. Below 3.0V, the resistance will begin to rise.

So what does this mean for 'minimum input voltage'? For the driver to give current to the LED, you should have at least 3.0V. For the driver to be in regulation, you probably need more than that.

The way to figure the minimum input voltage for regulation is as follows:
1. Select the design current. In this example, 9A.
2. Look up or measure the LED voltage at the design current. In this case, the SST-90 data sheet says typically 3.87V.
3. Calculate the voltage drop across the driver at the design current. In this case it's 0.03 ohms * 9A = 0.27V. That is the minimum resistance of the driver, times the design current.
4. Add the LED voltage to the Driver voltage drop. 3.87+0.27 = 4.14V.

So for this LED and this driver, you need 4.14V for the driver to be in regulation. If you were driving a red LED with voltage of 2.1V, it would stay in regulation all the way down to 3.0V. If you were driving two SST-90's in series, you would need 3.87+3.87+0.27 = 8.01V so it would regulate with input voltages of 8 to 12V (the max allowable input voltage).

Your LiIon cells probably will not put out 4.14V for very long.

Some people would say that means they are not a good choice for this LED and driver. But by that argument incans are always bad, because they always operate 'out of regulation'. The light output always starts dropping as soon as you turn on the light. The question is how much drop in output can you tolerate? A 50% drop in output is very noticable if it happens suddenly, but not if it happens over time.

Let's say you choose 50% as the tolerable drop in output. How much voltage is needed for this?

1. Half output is 0.5*9A = 4.5A.
2. The data sheet says the LED will need about 3.4V to get 4.5A in the LED.
3. The drop across the regulator will be 0.03*4.5 = 0.135V.
4. The voltage needed is 3.4+0.135 = 3.535V.

How long will it take your batteries to reach 3.535V? You will have to go to the battery data sheets, or test them to find out. It will depend very much on which cells you choose.

Also keep in mind that the biggest variable in the equation is the LED voltage. The data sheet gives a few numbers, and a graph. The graph is "typical" data, so your LED may be a little different.

For those interested in drivers other than the 10A one, the 8A driver has minimum resistance of 0.035 ohms and the 5A one is 0.05 ohms. By special order, I could build single-mode drivers with resistances down to 0.015 ohm.

I hope this helps answer your question.

D

[flashfiend]

Thanks, that was an excellent answer to my question. Btw, is this driver compatible with a D2flex controller?

[Delphinus]

This is the results I got from the IS1006-0820 with 2 LI-PO 5Ah 30C, I choose this battery for its ability to drain hi power and for the voltage that makes the circuit more efficient, ideally I should use 3 LI-PO but since I have 2 leds and only 4 cells I will limit the current to 5A.

I also tried 2 LiFePO4 in series but produces a lot of heat not a problem to use underwater but reduces the time.

[DIWdiver]

Thanks, that was an excellent answer to my question. Btw, is this driver compatible with a D2flex controller?

I haven't tested it, but I think this should be compatible with the D2flex.

D

[flashfiend]

I haven't tested it, but I think this should be compatible with the D2flex.

D

Sorry to bother you with this but could you explain how your driver would work with the PWM D2flex? Thank you.

[DIWdiver]

Sorry to bother you with this but could you explain how your driver would work with the PWM D2flex? Thank you.

Hopefully this will answer the question. Be careful that you don't exceed the rating of the d2Flex, which is only 6A.

[kris23]

do you have any IS1006-10100 or IS1006-1025 drivers on hand or on order? i would like to buy one soon.

[DIWdiver]

do you have any IS1006-10100 or IS1006-1025 drivers on hand or on order? i would like to buy one soon.

Yes, I have two that can be built either way on short notice. After that it's probably ten days for shipping of additional units.

D

[Al Combs]

for an IS1006-1025 + $4.95 for USPS flat-rate box.

Thanks for making these.

[kris23]

of $29.95 for ONE IS1006-1025 driver

thanks!

[DIWdiver]

Al Combs, kris23, those will ship Monday.

Then I'm out of stock. I have 14 more boards, for which I will order the parts to build them up. Demand has been higher than I ever expected. I never expected to sell more than 30, but 36 are gone and it's still going.

Once the remaining 14 boards are gone, I don't know if I'll order more. Since the cost of ordering boards is so high, I'd need to have 10-15 paid orders for it to make sense. Once that threshold is reached, it would be several weeks until shipping could start.

D

[Al Combs]

Got my IS1006-1025 in the mail today. That's great service, thanks.

Looking it over I have a question. I was thinking about using something like this for a heat sink in my MagLite. I noticed the ground of the TO-220 FET package is actually common to L- and not B- on the board. Not sure why I thought it would be the other way around. But if the anodizing on the inside of the battery tube is thin, would my 4*NiMH battery pack fry the LED? Do I need to use a mica shim to insulate it from the heatsink because it might be grounded? Just want to make sure the extra precaution is necessary. Or did I just misunderstand the situation? Hey I figure better safe than sorry...

Thanks

[Popsiclestix]

Just curious, would it be a bad idea to use one of these in a hotwire mod? Say something like an Mag85?

[Al Combs]

Have you seen these regulators that were actually designed for hotwires? Alan B's is just for a M*gLite or Elephant and JimmyM's, although made with M*G's in mind, could more easily be adapted to something else. Both have soft start, low voltage warning, high temp shutdown, user programmable...

[DIWdiver]

Just curious, would it be a bad idea to use one of these in a hotwire mod? Say something like an Mag85?

The IS1006 would work as well with incancescent load as with LED, but as Al Combs points out, there are better options for many applications. Incans are very tolerant of high voltage spikes, as long as the average is within reason. That allows a PWM driver like those he suggests to work really well.

LEDs would under such treatment. They want strictly limited current (which means you can't simply turn a high voltage on and off, like you can with an incan). This is why the IS1006 was developed. But in addressing the limitations of LEDs, it ignores one of the biggest strengths of incans.

Depending on your goals, the IS1006 could be either a clever or very foolish choice for a hotwire. Perhaps if you tell us what attracted you to this driver, we could help you decide which it is for you.

D

[DIWdiver]

Got my IS1006-1025 in the mail today. That's great service, thanks.

Looking it over I have a question. I was thinking about using something like this for a heat sink in my MagLite. I noticed the ground of the TO-220 FET package is actually common to L- and not B- on the board. Not sure why I thought it would be the other way around. But if the anodizing on the inside of the battery tube is thin, wouldn't my 4*NiMH battery pack will fry the LED? Do I need to use a mica shim to insulate it from the heatsink because it might be grounded? Just want to make sure the extra precaution is necessary. Or did I just misunderstand the situation? Hey I figure better safe than sorry...

Thanks

You are correct that the metal tab of the FET is connected to L-, not to B-. If the heatsink is connected to B-, then the FET should be electrically isolated from the heatsink.

This is discussed in the Assembly section of the datasheet, and was discussed in another thread, but apparently never in this thread. Thanks for getting it into the conversation here!

If you were to connect L- to the heatsink, which was connected to B- through the body, you would not damage the driver, but you would put the full battery voltage across the LED. Depending on your batteries and your LED, that could be REALLY bad, really fast.

If, on the other hand, the heatsink (and thus L-) were connected to B+, this would effectively short the LED. That wouldn't hurt the LED, but it wouldn't light up and you would have the full battery voltage across the driver. With really good heatsinking the driver could survive this indefinitely, but if the heatsink or the bond from the FET to the heatsink were less than optimal, the FET would eventually fail. With little or no heatsinking, this could occur within a few seconds.

D

[DIWdiver]

Parts are in for the next 14 boards!!

D

[Delphinus]

Parts are in for the next 14 boards!!

D

Can I use the circuit to drive 2 led’s in parallel, for example using one of 10A to feed 5A to each?

[DIWdiver]

Can I use the circuit to drive 2 led’s in parallel, for example using one of 10A to feed 5A to each?

Well, yes and no. I guess that means maybe.

If the LEDs are different, like a red and a green, then definitely NOT. They will have such different forward voltages that one would draw most of the current.

But you are probably talking about white LEDs (SST-50's?). The forward voltages are more similar among whites, but you may still need to be careful. If pushing the LEDs near their limits, you want them to carry equal current, so you want the forward voltages to be nearly the same. That means getting not only the same model numbers, but parts from the same voltage bin.

The good news is that if you buy all the LEDs at the same place and at the same time, there is a very good chance they will all come from the same bin, and so they would share pretty well.

D

[kris23]

hey DIWdiver, i have a little problem with the driver...

with 4 NI-MH F cells, apparently the vdrop at 10A is so low that the driver puts out so much heat that it begins to melt the flux and solder on the board...

what do you recommend as a heatsink for it?

[DIWdiver]

hey DIWdiver, i have a little problem with the driver...

with 4 NI-MH F cells, apparently the vdrop at 10A is so low that the driver puts out so much heat that it begins to melt the flux and solder on the board...

what do you recommend as a heatsink for it?

Most of these go in aluminum body lights. I would sink it to the body of the light, the way the LEDs are usually done. I did a light with a similar problem, and there is an aluminum wall behind the LEDs. The LEDs are attached to the front, and the driver to the back of this wall. Since this wall is part of the body of the light, there is excellent conduction of heat from the electronics to the body. With your setup the LEDs should generate 3-5x as much heat as the driver, so it should be easier to keep the driver cool than the LEDs.

Something to keep in mind, as Al Combs pointed out, you may have to electrically isolate the driver from the heatsink. The thermal tab of the driver is connected to L-, so if the heatsink is attached to some other voltage (often the body is connected to B-), you will have to isolate the driver. There are many ways to do this, but I'll mention two:
1. Anodize the heatsink and glue the driver to it with non-conductive thermal adhesive (Arctic Alumina ADHESIVE is a good one).
2. Get a thermal pad, a screw insulator, and some thermal compound (Arctic Alumina COMPOUND is a good one), and screw the driver to the heatsink with a #4-40 or 2.5mm screw.

Let me know if you need more help on this. There are many others around who can help as well. I can recommend or even give you some thermal pads and screw insulators.

D

[kris23]

i thought about this, but when i received the heatsink, Britelumens sink for SST-90, the holes for wires come out right in the center of the sink....

no way for the driver to contact the surface of the heatsink. however, given the amount of heat put out by the SST-90 at the full 10A, the driver seems to need something isolated from the main LED heatsink....

im hoping that i can find something that can accomplish this, what have you used as a heatsink?

[DIWdiver]

i thought about this, but when i received the heatsink, Britelumens sink for SST-90, the holes for wires come out right in the center of the sink....

no way for the driver to contact the surface of the heatsink. however, given the amount of heat put out by the SST-90 at the full 10A, the driver seems to need something isolated from the main LED heatsink....

im hoping that i can find something that can accomplish this, what have you used as a heatsink?

Can you provide any information on your build, i.e. what the head looks like? We could provide more targeted advice if we knew what the target was!

D

[Aircraft800]

i thought about this, but when i received the heatsink, Britelumens sink for SST-90, the holes for wires come out right in the center of the sink....

no way for the driver to contact the surface of the heatsink. however, given the amount of heat put out by the SST-90 at the full 10A, the driver seems to need something isolated from the main LED heatsink....

im hoping that i can find something that can accomplish this, what have you used as a heatsink?

I used the same BL heatsink as you, and came up with this screw on heatsink for the driver. It gives me just enough room to pass the wires threw.