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O-Like Constant Current Driver


TheMonk

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I have a feeling this might be use to drive the 808nm pump diode for green laser which operates around 2v out.

Just emailed o-like see what they say. :p
 

Warske

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REVENGE said:
I saw this today: http://o-like.com/b2b_cpinfo.asp?id=987.

What types of diodes could I use with this? Awfully cheap at 2 per $7.50 shipped.
Says it it does 80-500MA
So presumably it works for any diodes within that range. Maybe there is a diode voltage limit; hard to tell.

I ordered a set & will provide some more info when they show up.

BTW, these look very much like the ones from Qualifound that are being discussed here:
New Qualifound driver

Thanks for the heads-up!
 
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TheMonk

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Got reply from o-like, the MAX output voltage is 2.5V. This driver is for Green Laser.
 

33846

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Can you use a 5mw green's KTP crystal with a much more powerful infrared diode and get more green? or will it over saturate it? sorry to ask in this thread, just thinking of building a cheap but powerful lab-style green.


Devin.
 

The_Muffin_Man

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Devin.P said:
Can you use a 5mw green's KTP crystal with a much more powerful infrared diode and get more green? or will it over saturate it?  sorry to ask in this thread, just thinking of building a cheap but powerful lab-style green.


Devin.
Itll just fry the crystals :D
 

Warske

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Devin.P said:
Can you use a 5mw green's KTP crystal with a much more powerful infrared diode and get more green? or will it over saturate it?  sorry to ask in this thread, just thinking of building a cheap but powerful lab-style green.


Devin.
That question is being looked at in this thread: decan an 808 and add a DPM?
 
 

ElektroFreak

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I like the fact that they include TTL modulation capability. 5kHz isn't very fast, but it's better than nothing, IMO..
 

Warske

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First test results

Here are some test results on the o-like driver that is listed at
http://o-like.com/b2b_cpinfo.asp?id=987

These pictures from o-like show the hookup:



This is a linear current regulator with a low drop out voltage.

LD+ is tied to Power+ internally.

"Head room," therefore, is the voltage between LD- and Power-.

"LD- or null" measures about 3 ohms to "LD-" and was left floating in these tests.

TTL+ limits the output current to about 2.3 mA when left floating. It was tied to Power+ in these tests.

The input current is 10 mA to around 38 mA higher than the output current, depending on conditions. (It might be possible to reduce this by changing some resistors.)

Since this is a linear regulator, power dissipation depends mostly on the drive current setting and the headroom.

At the highest output current settings, the output is less stable because of temperature shifts as the driver heats up. This is mostly dependent on the power dissipation.

For the test load, I used between 1 and 7 silicon diodes in series with a 0.1 ohm resistor.

Current adjustment range
The one I tested had an adjustment range of 12 mA to 235 mA. One of the photos above suggests that you can replace one of the resistors to shift it to a higher current range. I didn't test this.

Input voltage range
Note that o-like specifies the input voltage as 5 v.
The lowest input voltage that provided regulation was 2.37 volts. I tested the driver with up to 11 volts in (with a 5.65 v load running at 122 mA). It probably could have gone higher. However, there is a larger thermal effect at the higher voltages.

Dropout voltage
I define dropout voltage as the lowest headroom voltage that sustains the output current within 5%. That is, dropout voltage plus load voltage is the lowest input voltage you can use and still get reasonable current regulation.

Load: 3 diodes plus 0.1 ohm resistor
Code:
  load mA    dropout v
  -------    ---------
     11.8      0.302
     51.1      3.46
    101.6      0.669
    121.5      0.800
    150.6      0.983
    208.0      1.350
    235.0      1.518
Thermal effects
Example 1
With 8.4 v in and 120 mA out into a 5.56 v load, the input current is 158 mA. The output current climbs to 123 mA after 15 seconds, then drops to 114 mA after 1 minute and 109 mA after 2 minutes.

Example 2
5.2 v in and 118.2 mA out into a 2.40 v load (the same pot setting as example 1), the input current is 140.7 mA. The output current climbs to 118.4 mA after 15 seconds, then to 119.7 mA after 1 minute and 120.6 mA after 2 minutes. After 5 minutes it is fairly stable at 121.0 mA. Blowing on the driver then drops the output current to 119.9 mA.
 




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