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Test loads?

Mrmask

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What are they and what do they do?

I have a digital multimeter. Why would I need to test the ampage with an additional circuit board.

Links are fine but please point to the correct page on them if it is a multi-page faq.
 

lasersbee

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Hmmmm... Time to do some research and reading....

Try "Test Load" or "Dummy Load" or "Dummy Test load" using
the [Search] button... that might work...:whistle:

Jerry
 
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On non linear drivers such as the Flexdrive, you need a test load to simulate the laser diode in order to set the current on the driver before connecting the real diode.

On linear drivers such as all the LM317 or similars based drivers (the DDL driver), all you need is your multimeter as load to set the current. These drivers will keep the current constant regardless of the load, so the multimeter itself will work just fine.
 
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On non linear drivers such as the Flexdrive, you need a test load to simulate the laser diode in order to set the current on the driver before connecting the real diode.

On linear drivers such as all the LM317 or similars based drivers (the DDL driver), all you need is your multimeter as load to set the current. These drivers will keep the current constant regardless of the load, so the multimeter itself will work just fine.
Flexdrive's have to have a load connected to them before power is applied. If you connect the diode with a DMM in series to measure the current, you run the risk of the driver being set too high and instantly blowing your LD.
Also, all LD to driver connections need to be soldered. Unless your willing to solder your DMM leads to the LD and driver, you risk a momentary open, even a micro-second open, IE: bad connection, will blow the LD, due to capacitor discharge.
And lastly, the less times you subject your LD to the heat of a soldering iron, the better off your diode will be.(without a test load, you have to solder wires to it to test, then desolder the wires, then resolder again to the driver)
 

mfo

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What are they and what do they do?

I have a digital multimeter. Why would I need to test the ampage with an additional circuit board.

Links are fine but please point to the correct page on them if it is a multi-page faq.
Read the guide in my signature.
 

Mrmask

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Thank you Hallucynogenyc and Greenmechanic for the advice.

I tried to read the guide but it really made little sense in this part in question. Was he trying to hook up 6 red diodes and 1 blue in the picture? Or were those extra electronics parts that should or shouldn't come with my driver.

Oh and I look at the first 3 threads that look relevant before posting. After that it's just easier to ask.
 
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Those 6 things are normal diodes. They have a 0.7V drop, so in order to simulate a red diode which has a 4V drop, we use 6 of them in series ;)

The "blue" thing is a resistor which we use to measure the current with the MM. It's called indirect current measurement, google it for more info.
 

mfo

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Those 6 things are normal diodes. They have a 0.7V drop, so in order to simulate a red diode which has a 4V drop, we use 6 of them in series ;)

The "blue" thing is a resistor which we use to measure the current with the MM. It's called indirect current measurement, google it for more info.
Actually, red diodes typically have around a three volt drop, so you should be using four diodes in series instead of six. Six diodes are used for blu-rays.
 

lasersbee

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Actually, red diodes typically have around a three volt drop, so you should be using four diodes in series instead of six. Six diodes are used for blu-rays.
Exactly.... That is the norm for RED and Blu-ray Laser Diodes respectively..

Jerry
 




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