Confused on laser output

BeavRat · Jan 22, 2009

With the ddl driver and 2 ohms of resistance on the pot, the max output should be over 420 mA with zero resistance on the pot. Even with the pot fully open, I only get 320mA. Whats wrong here? Do I need to add another battery to have 5AAs instead of 4? 2 ohms should go way higher than 420 mA...
I am powering a red open can long die.

Thanks

ndrew2505 · Jan 22, 2009

you need at least 7.2v to run a ddl circuit for a red and ~9v for a blu-ray

BeavRat · Jan 24, 2009

But why can't the diode take more than 300 mA? I keep turning the pot, but the amperage doesn't increase at all...

Diode_Virgin · Jan 24, 2009

BeavRat said:
But why can't the diode take more than 300 mA? I keep turning the pot, but the amperage doesn't increase at all...

I had a 10 ohm in series with a 100 ohm pot and had to add three more 10 ohms in paraellel to get my 400ma of current. Can anyone remind me of the formula that will allow me to replace my 4 x 10 ohm resistors in paraelll with only one resistor?

BeavRat · Jan 24, 2009

I have 1 ohm of resistance on the pot. This should easily be able to run at 400 mA. Why does output stop at 300 mA even with the pot fully open? Is it because I am only inputing 6 volts rather than the ideal 7.2?

Oh, and I know what the formula is, it's (r/1+r/1)-1

I used this and the lm317 calculator to find the correct resistor, but it still won't go over 300 mA

Mohrenberg · Jan 26, 2009

BeavRat said:
I have 1 ohm of resistance on the pot. This should easily be able to run at 400 mA. Why does output stop at 300 mA even with the pot fully open? Is it because I am only inputing 6 volts rather than the ideal 7.2?

Oh, and I know what the formula is, it's (r/1+r/1)-1

I used this and the lm317 calculator to find the correct resistor, but it still won't go over 300 mA

i would first trying going above the minimum working voltage for a red and ddl driver.

4x AA batteries will prob only give you 5.?V, you need atleast 7.2

BeavRat · Jan 27, 2009

Ok I figured it out. 4 freshly charged AAs can power the laser at 420 mA, but as the power drains below 6 volts, the power drops to 320 mA. WHen I stuck some new AAs, the voltage came out at 6.5 volts. Any less then 6 volts, the ddl driver can't pump out 420 mA.

Gazoo · Jan 27, 2009

BeavRat said:
With the ddl driver and 2 ohms of resistance on the pot, the max output should be over 420 mA with zero resistance on the pot. Even with the pot fully open, I only get 320mA. Whats wrong here? Do I need to add another battery to have 5AAs instead of 4? 2 ohms should go way higher than 420 mA...
I am powering a red open can long die.

Thanks

The problem with the LM317 is that it can have a voltage drop as high as 2.5 volts. It is a very good and stable regulator, and great to start with...easily available too. In fact I still am using mine...lol. But there are LDO (Low Drop Out) regulators that have drop out voltage ratings in the millivolts.

BeavRat · Jan 28, 2009

One more question, will the link below have a noticable increase on power with my open can red from a clear coat acryllic?

http://www.lasersurplusparts.com/index.php?main_page=product_info&cPath=8&products_id=9

Gazoo · Jan 28, 2009

Any glass lens with an AR coating will give you an increase in power. It will not be that noticeable unless you have a meter to measure with so you can take the readings and measure the differences. Is a glass lens still worth worth it? Yes.

jayrob · Jan 28, 2009

There is also another lens option for reds!

IgorT told me about these, I tried them, and they are awesome! They are in a nut that fits right into the AixiZ module (the back is already open too). Same focal length as the AixiZ acrylic, but they are AR coated for red.

You will get at least 20 or 25mW's more power with perfect beam and dot using these with red builds at 400+ mA's in comparison to the AixiZ acrylic lens!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350117036998
Jay

P.S. Welcome back Gazoo! Great to see you posting...

daguin · Jan 28, 2009

jayrob said:
There is also another lens option for reds!
IgorT told me about these, I tried them, and they are awesome! They are in a nut that fits right into the AixiZ module (the back is already open too). Same focal length as the AixiZ acrylic, but they are AR coated for red.
[highlight]You will get at least 20 or 25mW's more power [/highlight]with perfect beam and dot using these with red builds at 400+ mA's in comparison to the AixiZ acrylic lens!
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350117036998
Jay

P.S. Welcome back Gazoo! Great to see you posting...

Is there a difference when compared to the glass lens?

Peace,
dave

jayrob · Jan 28, 2009

Way better than AixiZ glass with reds!

As good or better output as the Meredith glass, but with the great focusing!

Correction: Not as good of output as Meredith glass. But a lot better than AixiZ glass.

All of my red builds have this lens now, with exception of the couple that I already have Meredith glass modules installed already...

In fact, using this lens, I get over 200mW's using a 1239JL-54 diode at only 275mW's! I chose this diode/current/lens combination for one of my Key Chain builds to keep the current as low as I could and still get 200mW's.

Jay

P.S. It's a normal diode too... It would give around 200mW's with an AixiZ acrylic lens at 300mA's.

jayrob · Jan 28, 2009

Yeah... just to further clarify. They are not the same power as the Meredith glass lenses.

But with many builds, you cannot fit a Meredith glass lens. Like a Kryton, or my new Key Chain. That's where you want this lens in a red build. It will give about a 10% power increase over an AixiZ acrylic. Where as the Meredith glass is about a 20% increase...
Jay

Gazoo · Jan 28, 2009

I was just getting ready comment on that...lol. Remember when we were comparing lenses? We were getting a 40 to 50mw increase with the meredith glass lens compared to the acrylic lenses. But the plastic lenses you posted the link to do look good.... and the price seems reasonable.

jayrob · Jan 28, 2009

Yes, I remember all of it! You were my main mentor!

I was so excited about these new lenses, that I temporarily forgot how great the Meredith glass lenses are! ;D (my latest Key Chain build won't fit a Meredith) Hmmm... I bet I could get a Meredith in there. I got a Meridith to fit inside a Leadlight...

I just did a comparison on my Ice Box red build that has a Meredith module in it. I put one of the AR coated acrylic lenses into a Meredith mount:

* 450mA's - 288mW's with the AR coated acrylic.
* 450mA's - 316mW's with the Meredith glass.

Jay

Confused on laser output

BeavRat

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Diode_Virgin

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Mohrenberg

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BeavRat

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Gazoo

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daguin

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