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Custom high current drivers for 445s?

jupiter8

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I'm wondering if anyone's come up with a design for a custom driver for these diodes yet? I'm keen to build my own, if we can discuss circuit/component details I'll give it a go. I'm not worried about size, this will be built into a lab/bench laser. Good heatsinking is more important than compactness in this application.
 



ReNNo

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Then Lm317 is perfect driver for you.
It's very stable driver and you can use pretty big capacitors to protect diode from voltage spikes.

If you have space for heatsink and about 7V power supply then this would be the best IMHO :)

What current you want to achieve?
 

jupiter8

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Judging by the reading I've been doing on the forum here I don't want to push it up to 1W. I'd like to start at 200 or 300mW and ramp up to maybe 700mW max. I'm thinking around 500mW is a good safe power for longer duty cycles - I want to play with scanners in the near future.

Just checked the online catalogue of my local electronics shop - they stock the Lm317 for about $6. Now I saw a simple circuit diagram somewhere on the forum, let me go a hunting.
 

ReNNo

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6USD for only one chip is too much.

What you need is adjustable LM317 chip, resistor, potentiometer, capacitor and heatsink.
If you want to limit current to 700mA then you need to use 1.78ohm resistor (1W or bigger resistor) and 5ohm potentiometer (1W or bigger).

Just connect resistor and potentiometer in series.
1.78ohm resistor will limit current to maximum of 700mA and with potentiometer you will be able to adjust current from 185mA up to 700mA.
 

styropyro

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I buy LM317 chips at my radioshack for a little over $2 piece, and parts there are expensive. My lab setup for my 445nm diode in the mail uses a LM317 driver and a network of resistors in series and parallel that should add up to 1.5 ohms. You will probably want to add a pot to make it adjustable. This driver can be built for under $3 with the right parts sources.
 

ReNNo

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He wants stable driver, he doesn't mind about heat.
LM317 can give up to 1.5A, if he needs more current then he can go for LM350.
 

yobresal

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Sorry if this is a tad off subject but can the Micro-boost and flexdrive both drive these 445nm diodes up to 1 AMP? If yes, aside from the normal voltage input requirements is there any limiting battery capacity which will hinder the 1 AMP driver power?
 

jbtm

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I have a question. It says to use a 10uF capacitor...Does more capacitance mean more protection...What im asking, is there a limit where more doesn't do much. I for fun stuck a 16V 150,000uF capacitor on it but I don't want to keep it on if its utterly worthless.
 

ReNNo

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Yes, you can use that capacitor.

LM317 doesn't have problems with large capacitors.
 

jaycey

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I am using a standard LM317 (DDL Design) driver 100ohm pot, 4 X 10ohm 1watt resitors in parallel (anyone tell me what the max out put with 4 x 10ohm resistors is?) 7.4v LiPo battery.

Duty cycle of 1 min on 1 min off, with no heatsinking on the driver.

Picture in my thread in the multimedia section.
 
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ReNNo

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When pot is set to 0ohm then maximum current will be 500mA (with 4x10ohm resistors).

You can set current from 12mA to 500mA.
 

jaycey

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Cheers, I thought I was maxing @ 600mah, but 500mah is enough for now...more than enough!
 

Elektrotechniker

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A lot of question are stated here as well as in other threads about 445 nm lasers.
@yobresal, I think max current is <1 A with a flexdrive. but with a micro boost you achieve more than 1 A. Eudaimonium said that on another thread.
 




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