Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers

 Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.

One laser store meets all your needs

 Laser Pointer Forums - Discuss Laser Pointers Do these numbers make sense?

LPF List of Laser Pointer Companies (link opens new window)

07-23-2013, 01:08 AM #1
 Junior Member Join Date: Apr 2013 Location: Ontario, Canada Posts: 8 Rep Power: 0
Stereo Joe
Junior Member

Join Date: Apr 2013
Posts: 8
Rep Power: 0
Do these numbers make sense?

Howdy, I've been lurking here for a few months and I'm onto my 2nd build now. I went a bit more DIY this time and built my own test load to set the driver current:

My diode is an Osram PL450B that I'm going to feed 200-250ma from a Micro Boost driver (fed by 1 li-ion battery). According to this thread, the PL450B drops about 6 volts at my target current: Osram PL450 450nm 80mW power chart

Based on my calculations, I should hook up my driver to the test load with 8 of the 1N4007 diodes in the circuit (0.7 x 8 = 5.6) to come close to the 6 volt drop of the PL450B. I just wanted to ask you experts if these numbers make sense since most of the info I read about the test loads suggests using either 4 or 6 diodes in the circuit.

LPF List of Laser Pointer Companies (link opens new window)

07-23-2013, 01:31 AM #2
 Class 4 Laser Join Date: Jun 2010 Location: St. Louis MO Posts: 5,482 Rep Power: 10819
DTR
Class 4 Laser

Join Date: Jun 2010
Location: St. Louis MO
Posts: 5,482
Rep Power: 10819
Re: Do these numbers make sense?

If you have a bench power supply you can test the voltage drop at the current you will be using. I believe those are rated 0.7V drop @ 1A so they could be dropping a lot less than that at lower currents. With the blueray setting on my test load it only drops 4V @ 300mA.

07-23-2013, 06:51 AM #3
 Junior Member Join Date: Apr 2013 Location: Ontario, Canada Posts: 8 Rep Power: 0
Stereo Joe
Junior Member

Join Date: Apr 2013
Posts: 8
Rep Power: 0
Re: Do these numbers make sense?

Thanks, DTR! Unfortunately, I don't have a bench power supply yet. I'm just getting started in this cool hobby and I'm ramping things up slowly with each build I do.

I've got a couple extra 1N4007 diodes loose - do you know of any way to test one with some basic equipment? Batteries, multimeter, etc...

I'm not going to be running my laser diode near its max so as long as I can use my test load to get the Micro Boost in the ball park in terms of current, I think I'd be OK. Then I'll fine tune once the actual laser diode is connected.

Last edited by Stereo Joe; 07-23-2013 at 06:51 AM.

07-24-2013, 10:09 PM #4
 Banned Join Date: Jul 2013 Location: Alabama, USA Posts: 15 Rep Power: 0
Sasquach
Banned

Join Date: Jul 2013
Location: Alabama, USA
Posts: 15
Rep Power: 0
Re: Do these numbers make sense?

Run your test load at the current you are interested in and use your DMM to measure the voltage across one of the diodes. This will give you an idea how much each drops at that particular current. All diodes aren't created equal so some of them may read a slightly different voltage.

07-24-2013, 10:41 PM #5
 Class 3R Laser Join Date: Aug 2010 Location: Rio Grande do Sul, Brazil Posts: 2,088 Rep Power: 165
Leodahsan
Class 3R Laser

Join Date: Aug 2010
Location: Rio Grande do Sul, Brazil
Posts: 2,088
Rep Power: 165
Re: Do these numbers make sense?

Start connecting the microboost to the load using 6 diodes and measure the voltage on all of diodes. You can measure in the series, not needed to measure one by one and sum. Just remember the output for this driver is minimum Vsource, maximum 13v, so don't feed it more than the test load drop...

But something you said sounds strange...
Quote:
 Originally Posted by Stereo Joe I'm not going to be running my laser diode near its max so as long as I can use my test load to get the Micro Boost in the ball park in terms of current, I think I'd be OK. Then I'll fine tune once the actual laser diode is connected.
Ball park? The diodes on the load sets a voltage drop, it don't go more or less accurate if you miss the actual quantity of diodes.
What would give you a "ball park" value would be a 10% tolerance 1ohm resistor.

When in doubt, you can always connect your DMM in current mode, "between" the whole test load and driver.

And you said "fine tune"... How will you do that? Turning the pot? lol. Thats >\$100 you're playing with... beware.

edit:
@DTR
The drop vary for each diode. Most are rated 1.1V drop @ 1A.
__________________
Any doubts, feel free to PM ou send me a visitor message! I'll help as I can.

Best regards,
Leonardo
__________________

* Deploying CNC router project soon...

DONATE!
The smallest donation will help, if you like this enormous information resource, just do it.

Last edited by Leodahsan; 07-24-2013 at 10:46 PM.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

All times are GMT. The time now is 05:07 PM.

 -- DarkShadows V5 -- Responsive LPF -2562016 -- Default Style Contact Us - Laser Pointer Forums - Archive - Top