Testing DDl's circuit

[Fusion2004]

My power supply consists of 4 AA Energizer Lithium batteries, and I thought that would be enough. When I measure their voltage after hours of non-use, it comes out to about 7 volts; and after an hour of on and off use, trying to test my circuit with the 4 rectifier diodes, it was around 6-6.2 volts.

And yet, instead of getting that range going up to 250mA, I'm only getting up to 190mA. Should I measure the Vout and Vadj pins to ensure that I have 1.25 volts flowing there?

 

[jayrob]

My power supply consists of 4 AA Energizer Lithium batteries, and I thought that would be enough. When I measure their voltage after hours of non-use, it comes out to about 7 volts; and after an hour of on and off use, trying to test my circuit with the 4 rectifier diodes, it was around 6-6.2 volts.

And yet, instead of getting that range going up to 250mA, I'm only getting up to 190mA. Should I measure the Vout and Vadj pins to ensure that I have 1.25 volts flowing there?

If you are using the 2 X 10 ohm resistors, with the 25 ohm pot, then yes, you should be able to turn it up to 250mA's. 4 AA X 1.5 is 6 volts. That is why the LM317 is dropping out. It is not able to maintain exactly 1.25 volts across it's sense resistor. Do you have a way of testing the driver with either 2 X 3.6 volt batteries? Or, add another AA or two into the battery pack. Then I'm sure you will see the range it is supposed to give.
Jay

 

[Fusion2004]

Yeah, my voltage between the Vout and Vadj was only around 1.07 volts.
And unfortunately, my battery holder only has 4 battery slots.

I have some 3.6V RCR123As on their way from DX, but my diode is going to arrive long before those batteries do. Meh, I'll run it off of 5-6 AAs then, until my Hong Kong Post package arrives.

Thanks for the info, Jay.

And just as a side question, I know the SenKat diodes have an operating current of 130mA, just about how high can I safely push that?

(P.S. Does anyone know where I can find CR123A battery holders?)

 

[jayrob]

Yeah, my voltage between the Vout and Vadj was only around 1.07 volts.
And unfortunately, my battery holder only has 4 battery slots.

I have some 3.6V RCR123As on their way from DX, but my diode is going to arrive long before those batteries do. Meh, I'll run it off of 5-6 AAs then, until my Hong Kong Post package arrives.

Thanks for the info, Jay.

And just as a side question, I know the SenKat diodes have an operating current of 130mA, just about how high can I safely push that?

(P.S. Does anyone know where I can find CR123A battery holders?)

Here's a link for the battery holders:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=BC2/3AE-ND

People are pushing the Sony/Senkat diodes to 250mA's. This will give you around 160mW's to 170mW's with an acrylic lens. I like to push these diodes a little more. I like 294mA's (4.3 ohm resistor, no pot). This will put you around 200mW's with an acrylic lens. At this power, it is best to have a nice heatsink!
Jay

P.S. We have been reading about some new diodes that Stonetek is selling that may be able to be pushed even a little more!
http://www.laserpointerforums.com/forums/YaBB.pl?num=1206910274

 

[photongeek]

You could also use a 1/4Watt 100 ohm resistor for a BluRay dummy load. It is fairly close to the dynamic resistance of the BluRay when running at around 40-50mA. You can also calculate the current in your head by measuring the voltage and dividing by 100.

That's a good point. Why can't we just use a properly valued resistor as a dummy load for any wavelength LD instead of the series connected diodes and resistor? Wouldn't that be a lot simpler?

 

[FokoF]

For the 803t diode what values do you use for the resistors and the pot? need to get about 160mA.......... or higher

 

[redsamuraidragon]

I am about to post a "How To" on testing DDL's circuit before adding the LD, I hope it is all pretty clear and with no errors. Those members who have been there, done that, would you please let me know if you disagree with anything therein.

Regards rog8811
*Edit Circuit layout attached to help with circuit testing

thanks dude, I looked everywhere for this layout..

 

[rog8811]

My Pleasure
It is nice to see it is still of use to folk....

Regards rog8811

 

[Droyd]

is 4 AA batteries bad to power it?

 

[rog8811]

is 4 AA batteries bad to power it?

If you are building a red 4 AA's will work when batteries are fresh but they will soon sag causing the LM317 to drop out of regulation.....

5 X AA will give 7.5v, much better......

Regards rog8811

 

[Droyd]

crap, i already bought the 4X battery snap
is there anyway to make a 5X battery snap?
and what happens if it drops out of regulation?

 

[rog8811]

Go to 3.7v rechargables http://www.dealextreme.com/details.dx/sku.5790

You can either use the 4 pack holder and short out 2 battery positions or get a 2 battery holder.

If the LM317 goes out of regulation at best you will get less output from the LD.
At worst... dunno never tried it

Regards rog8811

 

[caleb]

woah, it took a while for me to find this and its prety mad!

but, just double checking, instead of 4, i need to use 6 1N4001 for 803T Blu-ray.

thanks.

 

[rog8811]

but, just double checking, instead of 4, i need to use 6 1N4001 for 803T Blu-ray.

I have not used the LM317 for any of my 803T builds so I am not sure......
I am sure that someone who has done it will let us know soon

Regards rog8811

 

[caleb]

oh, so this driver is for 650nm :'(. is there a BR build then?

 

[nvmextc]

I use DDL/LM317 for BR sometimes, just change the resistor value for the current. and for a test load 6 IN4001 diodes instead of 4. and also increased voltage because the BR wants atleast 5v instead of 3v like the reds. even more at higher currents I believe. 9V battery seems to work alright <150ma. That's what I've found, I'm sure others on here have used this setup also. I'm not an electrical whizz though so don't understand what's going on in the circuit, all I know is that the end result works.