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FrozenGate by Avery

Using a DC/DC converter to power the laser

unfortunately theres no room for a power divider.
i need it to step it up to 7.5v-9v, keeping it small is important.
 





ah no i didnt know that, i was looking online and saw products. yea that will fit

i need help with the resistor values... what should i use?
sorry, im not in any kid of classes for electrical engineering so im struggling a bit to understand things for the first time.
any possibility i can get help with the schematic for the entire booster circuit including the lm3410 and divider? pretty please :D
 
Viroy... What do you need 7.5V for?

Not for a laser i hope? I almost get a feeling you want to put a linear driver (rkcstr's micro) after it?

The 3410 is not just a voltage booster. It boosts (or bucks) voltage to the exact level required for a certain current to flow through the load, and keeps adjusting it, so that the current is always the same. If you need it for a laser, the 3410 is a driver by itself. All it needs is a capacitor on the output, and you're ready to go.
 
IgorT said:
Viroy... What do you need 7.5V for?

Not for a laser i hope? I almost get a feeling you want to put a linear driver (rkcstr's micro) after it?

The 3410 is not just a voltage booster. It boosts (or bucks) voltage to the exact level required for a certain current to flow through the load, and keeps adjusting it, so that the current is always the same. If you need it for a laser, the 3410 is a driver by itself. All it needs is a capacitor on the output, and you're ready to go.
Click to expand...
it is just a voltage booster, which is designed to regulate current. but you can set it up for constant voltage (I think)
 
Well yeah, it is just a voltage booster, but it boosts the voltage in a way that keeps current constant, in the usual setup.

I was just trying to say, that since this is a laser forum, i almost have a feeling, he wants it for a laser.. :D
More specifically, for a PHR diode with rkcstr's micro driver after the 3410..

That's why i asked, just to make sure there is no confusion.
 
IgorT said:
Well yeah, it is just a voltage booster, but it boosts the voltage in a way that keeps current constant, in the usual setup.

I was just trying to say, that since this is a laser forum, i almost have a feeling, he wants it for a laser.. :D
More specifically, for a PHR diode with rkcstr's micro driver after the 3410..

That's why i asked, just to make sure there is no confusion.
Click to expand...
why would someone do such a thing?  :o
wait, thats not the emoticon i want to use, try this one :-?
 
Well, there is more than one thread about "such a thing", and if you read the beginning of this one, i also first thought about "such a thing".. :-[

That's why i asked.... In case they think the 3410 can only boost the voltage to a certain value, and not regulate the current as well.
 
I was joking, damn emoticons. i needed one that winks and raises its eyebrow at the same time... or something
 
Hey I've got a weird problem with my lm3410 can anyone give me some advice?

I've got it set up and at least its boosting, so I suppose I've set it up right. :P But it doesn't seem to exactly be regulating. With a 1ohm resistor between FB and Gnd, I get about 100ma current, so about 100mv across those 2 pins. With a 2.2, that voltage goes to about 240mv, so the output is a bit above 100ma. Then with a 4.7, the FB goes to a whopping 380mv, and I get about 75ma at the output.

Any help would be appreciated.
 
what are you using as a load for your tests?
try using a 20ohm resistor as a load, and a 1 ohm resistor as the sense resistor. you should be reading 3.8V across the load.

and never power up the circuit without a load
 
I was using 6 or 7 diodes as a test load before. With 20 ohms of resistance as a load it was a bit better. FB voltage was .16 so the voltage across the load was 3.25.

I still don't know what to put it down to. I've got a 4.7uh inductor, 2.2uf ceramic at the out and a 2.2 ceramic paralleled with a 10uf tant at the in.

Stupid hyperactive reference voltage :-[
 
hmm i would say its the output capacitor. put a 10uF ceramic or tantalum on the output as well.
FB voltage should be constant at 0.19V I reckon its struggling to keep it constant because of the output cap
 
Does the output cap provide the actual output (as opposed to filtering) on one part of the cycle? I'll try a tant (the biggest ceramics I have are 2.2)

It doesn't seem to be struggling since the FB voltage goes above 300mv when i use a 4.7 ohm resistor. Its just all over the place :'(

Could it be the inductor? I gave it a lot of heat when I was soldering since I figured it was a lump of metal.

EDIT: Just tried a tant. No difference, or not much.
 
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