help with my LM317 regulator circuit!

• Mar 7, 2008

• #1

thebucketmouse

0

Joined

Feb 9, 2008

Messages

273

Points

0

I built this circuit from Daedal's plans, and i followed everything except I replaced the 100 ohm potentiometer with a 10 ohm resistor (until I can find the right pot). Anyway when I hook an LED up to the output, it flashes bright for a split second then glows a dull color... isn't this kind of surge exactly what this circuit is supposed to PREVENT?? what did I do wrong?

 

• Mar 7, 2008

• #2

C

chido

0

Joined

Dec 4, 2007

Messages

1,918

Points

0

A 10 ohm resistor in DDL's drver let's thorugh 125mA which I think is way to much for an LED and thus kills it, I don't know if a dead LED still emits a little bit of light like a LD, but I'm sure you killed the LED.
Here's the thread on how to properly test your driver:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1197651171

 

• Mar 7, 2008

• #3

thebucketmouse

0

Joined

Feb 9, 2008

Messages

273

Points

0

Thanks, that's exactly what I was looking for. But I'm new to circuitry and confused: why can't I just test the voltage and mA right at the output wires in my circuit?

 

• Mar 7, 2008

• #4

pocketfluff

0

Joined

Oct 25, 2007

Messages

221

Points

0

You can.

BTW, did you short the capacitor before you connected the LED?

 

• Mar 9, 2008

• #5

thebucketmouse

0

Joined

Feb 9, 2008

Messages

273

Points

0

no, i guess i didnt. but i will from now on.

so what should my bluray be running at? a 9 volt battery converted down to 6 volts, at about 40-50 milliamps, right?

 

• Mar 9, 2008

• #6

FireMyLaser

0

Joined

Jan 12, 2008

Messages

3,290

Points

83

Max 38ma or threshold current + 10ma for br.

 

• Mar 10, 2008

• #7

thebucketmouse

0

Joined

Feb 9, 2008

Messages

273

Points

0

Aight, I got everything running right. Im getting about 8 volts at whatever amperage I want to the laser diode (at maximum resistance, I get 10 milliamps). However, whenever I plug in my laser and power on, every time I only get a little flash of purple then it goes off, no matter what amperage it is! Have I killed my diode? :[

 

• Mar 10, 2008

• #8

C

clwatkins10

0

Joined

Jan 29, 2008

Messages

606

Points

0

um, it kinda sounds like it :-[, but i dont know much about br

 

• Mar 10, 2008

• #9

B

bobobob121

0

Joined

Feb 8, 2008

Messages

728

Points

16

its highly possible, that little light is most likely the electricity shorting its circuit inside the diode.

 

• Mar 10, 2008

• #10

FireMyLaser

0

Joined

Jan 12, 2008

Messages

3,290

Points

83

thebucketmouse said:

Aight, I got everything running right. Im getting about 8 volts at whatever amperage I want to the laser diode (at maximum resistance, I get 10 milliamps). However, whenever I plug in my laser and power on, every time I only get a little flash of purple then it goes off, no matter what amperage it is! Have I killed my diode? :[

Click to expand...

Did you have the power on, like the battery when connecting the LD?
If so, thats what you did wrong  :-/
You have to solder the LD to the circuit before adding the power.
Better luck next time.

 

• Mar 10, 2008

• #11

thebucketmouse

0

Joined

Feb 9, 2008

Messages

273

Points

0

you guessed it. owell, at least theyre cheap now