1 Watt 445nm - Flashing on and off?

daguin said:

The problem is that the diode is only going to pull ~4.5V. The microboost is not built to "drop" voltage, only boost. New batteries' voltage may exceed the diode voltage

If drlava said it was cool, I would trust him

Peace,
dave

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If lava builds these then wouldnt I trust his manual (im assuming he writes them) and be safe with up to 5.5 volts?

Through some testing with the microboost outside of the host and attached to a test load I have seen this type of behavior through a DMM. I watched the power start to climb to 950mA and then suddenly drop off. When I touched the driver it was very hot! An insufficient battery source (cheap 18650) and insufficient wiring (too thin) were to blame. Using heavier gauge wire and a better power source rectified my situation.

RA_pierce said:

2 AA batteries cannot supply sufficient power to the diode.

Use a single 18650 instead or turn the power down.

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AA alkaline should be able to provide 3W each, briefly*, when fresh.
Your diode requires something like 4-5W and the driver is less than 100% effective.

I recently tested both a AAA and a AA with a calliper and a clamp DC-meter, they provided 3A and 9A. That gives an internal resistance of ½ ohm and 1/6 ohm.

If I had not forgotten most of my high school maths I could make a nice curve over output effect as a function of load resistance/total current. What happens is that at high currents most of the voltage drop happens inside the battery giving you next to no effect out of it, it just gets hot.

*I agree, the problem is the batteries.

Braddubya said:

If lava builds these then wouldnt I trust his manual (im assuming he writes them) and be safe with up to 5.5 volts?

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5.5V is the absolute maximum allowable input voltage.
BUT the load should have a forward voltage higher than the input.
A boost driver draws extra current from the battery to "boost" the voltage. Since the MicroBoost is a boost only driver, the load must have a higher Vf to function properly...
Unlike the MicroFlex, which is a buck/boost and can "buck" extra voltage down if it is too high.

Again, I recall him stating that the MicroBoost is ok to use with an 18650 (4.2V) and a 445nm diode driven at ~1A.

At 1A, the Vf of the diode is ~4V. A fully charged 18650 will be around 4.2V. Since it is less than 0.35V over the load, it is ok.
If the battery source is greater than 4.35V, the voltage would be too high for the MicroBoost.

So basically, the input voltage should never be 0.35V higher than the Vf of the load, regardless of what the maximum allowable input for the driver is.

Edit:

Toke said:

AA alkaline should be able to provide 3W each, briefly*, when fresh.
Your diode requires something like 4-5W and the driver is less than 100% effective.

I recently tested both a AAA and a AA with a calliper and a clamp DC-meter, they provided 3A and 9A. That gives an internal resistance of ½ ohm and 1/6 ohm.

If I had not forgotten most of my high school maths I could make a nice curve over output effect as a function of load resistance/total current. What happens is that at high currents most of the voltage drop happens inside the battery giving you next to no effect out of it, it just gets hot.

*I agree, the problem is the batteries.

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In my 445nm Evo, I tried Alkalines and 2700mAh NiMH. Both could only power the laser for a few minutes or so before the power became intermittent. This was with the MicroFlex, power set at 375mW with acrylic lens (~450mA-500mA). The MicroBoost is less efficient than the MicroFlex. The actual capacity of the AA batteries is not sufficient to power the laser for more than a few minutes. I had to reduce the current so that the batteries could keep up with what the driver was asking for. I doubt a MicroBoost and a diode begging for >4W could be sustained by a power source that can hardly keep up with a ~2W load.

I didn't keep up with my math either - I feel you.

I only bought the microboost because the guy emailed me saying the microflex was out of stock and the microboost would work the exact same. I feel cheated because IMO the microboost sucks for a 445 diode drive as 2x aa, aaa, c, d cell batteries arnt enough and 3 aa, aaa, c, d cells are too much. What a crock I want my money back and the flexdrive that I originally ordered.

For now I guess ill go out and buy a battery and charger that I have no future use for just so I can run a test to see if thats the problem. Then I will have to decide if I want to add additional circuitry or junk the current host I have been working on. Awesome.

Braddubya said:

I only bought the microboost because the guy emailed me saying the microflex was out of stock and the microboost would work the exact same. I feel cheated because IMO the microboost sucks for a 445 diode drive as 2x aa, aaa, c, d cell batteries arnt enough and 3 aa, aaa, c, d cells are too much. What a crock I want my money back and the flexdrive that I originally ordered.

For now I guess ill go out and buy a battery and charger that I have no future use for just so I can run a test to see if thats the problem. Then I will have to decide if I want to add additional circuitry or junk the current host I have been working on. Awesome.

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You are not cheated.
The MicroBoost is a great driver and I used one in one of my 445nm lasers. You just need the right power source for it.

AA and AAA batteries are not good for any high-drain devices, really.
There are no AA batteries that can power a 445nm diode at 1W reliably. Period.

The battery source is the problem, not the driver.
Your setup will work just fine with 3 D cells as long as you add a diode to drop the voltage, which is not hard.

There is no need to buy an extra battery and charger. The MicroBoost will "pulse" the diode if it is not getting enough power. I've seen it myself. In my case, I just had to recharge the battery.
The same thing happened with my Evo example above, only with the MicroFlex.

Does anybody know a Linux program that can make a pretty coordinate system with equations like these as input?

Pl=2,25/(Rl^3+Rl^2+0.25Rl)
Pl=2,25/(Rl^3+ R^l2+1/36Rl)

Do NiMH come in D size? What's wrong with using quality NiMH? If people use them for their high power modded m@gs, why not for a measly 4W device?

I had the same pulsing problem, and had the same responces you have here , everyone was saying its a poor quality batt ect, everyone, i knew it wasnt as it did the same thing powered from my LAB PSU , but i followed advice and orderd trustfire 2500mA 18650's and charger, the result? exactly the same, as i expected....turned out the microboost was overheating, so i heatsunk it using the heat transfer pads off the RAM on a scrap XBOX360, and pressed it against the microboost, then pressed the entire thing against the case of the host. no more pulsing!. But what people are saying in this thread is right, dont bother with AA's ect, your wasting your time, it has to be at least D size rechargeables.

ped said:

I had the same pulsing problem, and had the same responces you have here , everyone was saying its a poor quality batt ect, everyone, i knew it wasnt as it did the same thing powered from my LAB PSU , but i followed advice and orderd trustfire 2500mA 18650's and charger, the result? exactly the same, as i expected....turned out the microboost was overheating, so i heatsunk it using the heat transfer pads off the RAM on a scrap XBOX360, and pressed it against the microboost, then pressed the entire thing against the case of the host. no more pulsing!. But what people are saying in this thread is right, dont bother with AA's ect, your wasting your time, it has to be at least D size rechargeables.

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It's pulsing "after a few seconds." If the driver is overheating in a few seconds, then something else is wrong.

Unless we/he can identify the "something else", then my bet is still on battery or connection issues

Peace,
dave

daguin said:

It's pulsing "after a few seconds." If the driver is overheating in a few seconds, then something else is wrong.

Unless we/he can identify the "something else", then my bet is still on battery or connection issues

Peace,
dave

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Yeah i hear ya.

A few seconds is a bit quick...mine lasted about 20 seconds before overheating, so your probably right, especially if he's maxed out the driver, with crap batteries.


edit....have a nose here http://laserpointerforums.com/f65/m...-flex-boost-driver-read-54959.html#post774452

I moved to a nicer 3.6v rechargeable pack out of a flashlight and it the same story. Ill try heat sinking.