Alternate power source?

[theman101]

Hey LPF, first I just want to thank you guys for having such an informational forum There's a lot of good stuff in here. I learned enough to feel confident enough to but the parts for my first build, based on a PHR diode and a DDL (LM317T and 10 Ohm) driver. Everything I need has arrived, except for my host and batteries (x2 14500). I ordered these from dinodirect, and shipped around the time everything else arrived :/ My question is, is there what is a convienient way to power my diode (looking for ~120mA) until my batteries arrive?

Thanks.

 

[LtKernelPanic]

I use a 6xAA holder with NiMH AAs when testing DDL drivers which gives around 8.4v at full charge. I also have a 2xAA to use with two 10440s or 14500s as well as a 4 and 8xAA to use with NiMHs if I need more or less juice. If you have a breadboard you can test it on there. Just whatever you do *DO NOT* direct power the diode off a battery. It will fry the diode within minutes. I have pics of a DDL driver I built powering a red diode on a breadboard if you want to test your build before the host and batteries arrive.

 

[sampson]

Hey LPF, first I just want to thank you guys for having such an informational forum There's a lot of good stuff in here. I learned enough to feel confident enough to but the parts for my first build, based on a PHR diode and a DDL (LM317T and 10 Ohm) driver. Everything I need has arrived, except for my host and batteries (x2 14500). I ordered these from dinodirect, and shipped around the time everything else arrived :/ My question is, is there what is a convienient way to power my diode (looking for ~120mA) until my batteries arrive?

Thanks.

I use an old ATX computer power supply. I cut back all the wires and tucked them safely inside then installed banana jacks for +12V +5V +3.3V and GROUND. Here is a link to some instructions for this:

How to Convert a Computer ATX Power Supply to a Lab Power Supply - wikiHow

You can also use old wall warts if they output sufficient current; I've got a lab module powered by an old 9V 1A ac/dc adapter that I found in the trash.

 

[theman101]

...I have pics of a DDL driver I built powering a red diode on a breadboard if you want to test your build before the host and batteries arrive.

That's great for reference!

 

[LtKernelPanic]

I didn't want to spam your thread with pics without asking first. Here's two pics with short explanations that may help you.


DSC_0427 by ltkernelpanic, on Flickr

The diode in the picture is a 5mW 635nm red that operates at 40ma normally. The closest I could get to 40 was 42ma using 30ohms of resistance. I didn't have any 30ohm resistors so I used three 10s in series. The 1N4001 1A diode is there to stop me from frying the diode if I connected the leads backwards - which I did do at least twice while not paying attention. I didn't bother with the multi turn pot for a low powered build.




2010-11-08_08-59-55pm by ltkernelpanic, on Flickr

There are actually a couple circuits on my board in this pic. I was actually testing the driver that would power the diode in a pen host. It has a 30ohm resistor soldered across the adjust and Vout pins setting it to 42ma. To the left of the red lead you can see what was part of the driver in the previous pic. The other important circuit on the board is my test load. When testing the driver's output for a red there would normally be 4 diodes in series then the 1ohm 1 watt resistor. I moved one diode to my ground line to protect against a reverse polarity spike killing the diode. For a 405 you'd want 6 diodes in series to estimate the volatage drop from the diode. In theory if you used the right resistor you shouldn't have to check a LM317 based driver with a test load but I always do. The extra 2 minutes to set it up is worth not frying an expensive diode in case something went wrong.

You can see the full sized pic on flickr if you have trouble seeing what's plugged where on the breadboard.

 

[theman101]

Thanks for your advice, LtKernelPanic! I wired up a set using x6 AA batteries, but only got a very dim light. I think I'll wait until the rest of my items arrive for further testing. Again, thanks for your help!