Bought an lm337 by accident

Likquidblur · Feb 7, 2011

So i have almost finished soldering my first driver (just missing the zener diode) and i have realised i bought an lm337t by accident so it is the opposite to the 317t, is it possible to power this backwards, and change the way the zener diode is solderd to counteract this. Or should i just desolder the 337 and replace it with the 317.
any help would be appreciated

heres a pic too, pretty much my first time soldering on a pcb, be nice

-likquidblur

Benm · Feb 7, 2011

Just replace it with a 317, its less work. By the looks of that circuit board its not complicated to replace at all.

You can use the 337 to build a mirror image of the driver, in case you ever have a case-positive host, for example, a green dpss laser.

Leodahsan · Feb 7, 2011

thinking logical, lm337 being a negative terminal regulator, he regulates his negative input. in lm317, the GND wire passes thru (from batt to LD), but in lm337 the POS wire passes thru (from batt to LD).

Likquidblur · Feb 7, 2011

Okay thanks benm,
thought i would need to in the end, lucky this stuff isnt expensive at all.
Thanks for fast reply also.

Likquidblur · Feb 7, 2011

thanks also for replying quick Leodahsan, but i'll just replace it. Less faffing about adding extra wires and what not, im a lasy bum

HIMNL9 · Feb 7, 2011

Careful, the 337 IC have still an NPN darlington as output, and its ADJ pin is connected with a reversed diode to VO, so you can use it as current regulator, but it works better through VI than through VO as you can do with the the 137 serie.

Leodahsan · Feb 7, 2011

I was writing something similar HIMNL.

@Likquidblur
NP. check teh datasheets.

Likquidblur · Feb 7, 2011

ohhhh sorry leo, i thought you were getting at it being easier to just switch regulators,
well i will try what i said in the first post, it'll just be less efficient, im hoping i understand properly, its 1230 here so sorry if im not.

Leodahsan · Feb 7, 2011

Don't be sorry, we're learning everyday !
Just read the datasheets, they commonly have example circuits and so. Just beware with VOLTAGE REGULATOR and CURRENT REGULATOR..

I'm not sure but, the 337 **may** have a different pinout than 317.

Likquidblur · Feb 7, 2011

:thanks: for the help guys/girls, little bit more reading is in order ...night/morning

Leodahsan · Feb 7, 2011

^
Yeah I didn't get it too :O

Likquidblur · Feb 8, 2011

Was up to some thinking and realised, if i only reverse the curent the laser diode will be getting hit with the full nine volts, and if i turn around the 337 and the zener diode it wont change a thing (will continue to be the oposite of the 317) and the man in at leading edge confirmed it. So ive just replaced the 337 with the 317's
But thanks for all the replies

-likquid

Leodahsan · Feb 8, 2011

I'm sleepy, I can't really read.. It worked?

Likquidblur · Feb 9, 2011

I havent recived my LD yet, but it lit up an LED so i know there is current passing through. i will make a test load soon aswell.

Leodahsan · Feb 9, 2011

lol @ your sig, maybe you meant 'porn' instead of 'pron' ?

ontopic: make sure you get that test load first than your LD..

Likquidblur · Feb 9, 2011

haha yeah i put it like that on purpose, dont want anyone get in offended by something stupid like that(still figuring out whats acceptable to say on here but every thing seems chilled)

Yes definitely, dont want to blow up my first LD, btw does the driver look ok to drive a 1W 445, it will only be running at 100mW tho, i built it off these plans.

Bought an lm337 by accident

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