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12X BR Diode - LM317 Based Driver Set Up

Helios

Helios

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Im going off of this schematic from Rog8811's website

LM317%20components01.jpg


Im shooting for 500mA using this design minus the pot and just using the correct resistor.

Im using 1/4W resistors so I may use several in parallel so I they dont get to hot. According to my calculations I need 2.5ohms.

Anyone see any problems with this setup? Can I use the same diode and cap for this higher current setup?

Also can I use the regular tail clicky even though the switch would be on the negative side of the circuit?
 
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A

anselm

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No. Yes and Yes. Yes.:D
But don't use those diode pins as in the picture, but I guess you knew that.
 
rhd

rhd

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Wait, what are you planning to use as a battery supply ?
 
rhd

rhd

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There's a problem with this driver design then. You're going to need 6V for the diode itself. (PIV Curve)

By the time you factor in 2.5 to 3 V drop from the LM317, the two batteries supply of 8.2V max, still won't be enough to deliver that 6V. It might deliver 5.5V max, which would cut your current down to like 150mA based on the PIV curve linked above.
 
Helios

Helios

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rhd said:
There's a problem with this driver design then. You're going to need 6V for the diode itself. (PIV Curve)

By the time you factor in 2.5 to 3 V drop from the LM317, the two batteries supply of 8.2V max, still won't be enough to deliver that 6V. It might deliver 5.5V max, which would cut your current down to like 150mA based on the PIV curve linked above.
Click to expand...

hmmm that is a problem. How did your setup work in my host? I know you didnt use the lm317 but could I configure it similar to yours?

If I use 2 cr123a im short voltage but if I use 3 I am over the 12V limit when bats are fresh.
I think I can fit 3 cr123a in one of my hosts with a custom heatsink but I will need to drop the voltage with a diode right?
 
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BShanahan14rulz

BShanahan14rulz

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*IF* you are comfortable using Li-Ion, that should give you an extra ~1.4V nom to work with, with a max of 8.4V on fresh cells.
 
rhd

rhd

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Helios, since you're just running at 400mA, you could actually use LM1117s. They're lower dropout and probably net you a good extra Volt, if not maybe even 1.5V more wiggle room than a 317. Do you have any 1117s ?
 
Helios

Helios

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rhd said:
Helios, since you're just running at 400mA, you could actually use LM1117s. They're lower dropout and probably net you a good extra Volt, if not maybe even 1.5V more wiggle room than a 317. Do you have any 1117s ?
Click to expand...

I have a dozen lm317 I bought to make drivers with since they seem the most popular but now im starting to regret it. What do others do to power these diodes with these regulators?
 
rhd

rhd

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For 405nm 12x DIY drivers, the 1117 is a good choice, because the dropout voltage is lower, so you can use 2x cells. Plus, the current limit of 800mA is no big deal, since you're probably running a 12x under that.

For me, I would use:

For 650nm - LM317
For 445nm - LM1085
For 405nm - LM1085 or LM1117

The circuit is exactly the same, except that you need another capacitor across the +/- input, not just the output.

Do you want some 1117s? I've got a bunch more than I need, I'd be happy to drop some in an envelope to you tomorrow morning.
 
chipdouglas

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you can use the rcr123's those are generally 3.7v also. why not use a 2watt resistor? they are just a hair larger.

michael.
 
rhd

rhd

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BShanahan14rulz said:
try some 16340, CR123a are 3V.
Click to expand...

...not really true. Whether or not that is technically accurate, the following are pretty much used interchangeably:

- CR123
- CR123A
- RCR123
- RCR123A
- R123
- 16340
- 17335
- 17340

You can try to dissect the proper meaning of each, but it's a fairly useless debate, since the naming conventions aren't used universally anyway.

About all you can tell for sure is that the "R xxxx" names will imply rechargeable.. but that's about it. And that doesn't work in reverse - IE, something called a "16340" is possibly (likely) rechargeable too, etc, but it still might not be.

If it's a lithium, it will be 3V, if it's lithium ion, it will be 3.7 (same as any other lithium ion). If it's a LifePo4, it will be 3.0 or 3.2V. Or, it might be a rechargeable Lithium Ion with a protection circuit that limits it to 3V for compatibility in older devices.

IE, lots of stupid complexity here, but the bottom line is that I think Helios WAS using the right batteries :)
 
Helios

Helios

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rhd said:
...not really true. Whether or not that is technically accurate, the following are pretty much used interchangeably:

- CR123
- CR123A
- RCR123
- RCR123A
- R123
- 16340
- 17335
- 17340

You can try to dissect the proper meaning of each, but it's a fairly useless debate, since the naming conventions aren't used universally anyway.

About all you can tell for sure is that the "R xxxx" names will imply rechargeable.. but that's about it. And that doesn't work in reverse - IE, something called a "16340" is possibly (likely) rechargeable too, etc, but it still might not be.

If it's a lithium, it will be 3V, if it's lithium ion, it will be 3.7 (same as any other lithium ion). If it's a LifePo4, it will be 3.0 or 3.2V. Or, it might be a rechargeable Lithium Ion with a protection circuit that limits it to 3V for compatibility in older devices.

IE, lots of stupid complexity here, but the bottom line is that I think Helios WAS using the right batteries :)
Click to expand...


Im talking about 3.7V Li-Ion cells. rhd very kindly will be sending me some lm1117s so I will use one of them as a regulator because of the lower drop so I can use the batteries I currently have. Thanks rhd!
 
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