Problem With LM317 "driver"

Tingawinga5 · May 25, 2012

So I've made a nice little LM317 circuit and did some research so I thought I knew how to set the current accordingly. However when in actuality my laser diode is very very dim, I was wondering if anyone can correct my error.

Here's my diagram
http://i.imgur.com/chWj5.jpg

I also tried this with 2x 1 ohm resister in series instead of the 2x 10ohm parallel>

Thanks in advance guys!

Blord · May 25, 2012

We need more info. What kind of diode is used ?

Tingawinga5 · May 25, 2012

Blord said:
We need more info. What kind of diode is used ?

Certainly sir, Its from a Sony DRU-800A DVD Burner big yellow sticker claims its class 3B, But I've read reports of people pushing this diode to 350mW with 650mA obviously with a heatsink

Anything else you need to know?

Things · May 25, 2012

Make sure you have the red diode and not the IR one, as they appear dark red and are very dangerous if you aren't careful.

Also, I'm not sure what diode it is, but usually the max current for DVD reds is under 400mA. You may have killed it. If it gets hot and is dim, it's dead.

Tingawinga5 · May 25, 2012

Things said:
Make sure you have the red diode and not the IR one, as they appear dark red and are very dangerous if you aren't careful.

Also, I'm not sure what diode it is, but usually the max current for DVD reds is under 400mA. You may have killed it. If it gets hot and is dim, it's dead.

Its the red one I use my camera to test which is which, I could have blown it but it seems unlikely. But moving away from the diode (I have a spare if it has blown) how does the driver circuit look? I was concerned the Vout and the Adjust might not be the right way round?

Thanks guys btw

Things · May 25, 2012

The driver is correct. Did you discharge the capacitor before connecting it to your diode?

Like I said, 650mA is too high for a regular DVD red. Try with something like 300mA and see if it works.

Dan

Tingawinga5 · May 25, 2012

Things said:
The driver is correct. Did you discharge the capacitor before connecting it to your diode?

Like I said, 650mA is too high for a regular DVD red. Try with something like 300mA and see if it works.

Dan

The driver pictured above has about 250mA output, and I had the thing wired up to my battery then tested the colour diodes with it so would that blow the diode?

Blord · May 25, 2012

You are pushing it too hard. I would start with a current of 300mA MAX.
I never heard of a red diode in a DVD burner goes that hard.
Only the known diodes like LPC-815 or LPC-826 will go 400mA/500mA respectively.

If the laserdiode is dim at 300mA then it is LED.

Blord · May 25, 2012

Tingawinga5 said:
The driver pictured above has about 250mA output, and I had the thing wired up to my battery then tested the colour diodes with it so would that blow the diode?

You said you tried with 2x 1ohm in series. That could killed the diode.

Tingawinga5 · May 25, 2012

Blord said:
You said you tried with 2x 1ohm in series. That could killed the diode.

Yes it probably has, but I did try this circuit first and it was quite dim, I'll try another diode soon.

Would having the circuit switched on then connecting the diode have killed it do we think?

Things · May 25, 2012

If you connected the circuit to the battery, THEN connected the diodes, then yes, it definitely killed it. That capacitor on the output stores up charge, which, when you connected the diode, dumped all that energy into it at once.

Tingawinga5 · May 25, 2012

Ok thanks guys! I now know for next time!!

Cyparagon · May 25, 2012

One 1n4001 is enough. Get rid of the one on the right.

Problem With LM317 "driver"

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