Why test load... Is it necessary?

NKO29 · Jun 12, 2013

Hey i am doing my first ever laser build from scratch, and i want to know a few things about test loading. i am using a LPC-826 diode with a c6 host and an aluminium heatsink, it will also be powered from a mohgasm linear driver set to about 400mA.
do i need to use a test load, or can i directly read off the + and - outputs from the driver with my ammeter?
and i cant seem to find an explanation for test loading apart from "to save my laser" so what is the actual use of doing it?
Thanks for reading and sorry if i am asking an already asked question

lasersbee · Jun 12, 2013

If you need to ask this question that has been asked and
answered hundreds of time before then you have not done
any reading on research on the Forum.

The search bars at the top of every page are your Friends...

Jerry

NKO29 · Jun 12, 2013

i do understand your answer, but in my searches 2 solutions have come up- yes and no... i am sorry for asking a question that has been answered before but i am asking because to me there is no clear answer because there are multiple answers.
sorry if my question annoyed you, but please understand from my POV

Eradicator · Jun 12, 2013

Quick and easy. Yes its necessary, so you can verify the output of your driver so you don't destroy expensive diodes.

lasersbee · Jun 12, 2013

NKO29 said:
i do understand your answer, but in my searches 2 solutions have come up- yes and no... i am sorry for asking a question that has been answered before but i am asking because to me there is no clear answer because there are multiple answers.
sorry if my question annoyed you, but please understand from my POV

If you want to increase the possibility of your Driver+Laser Diode
setup to function properly and not Damage or destroy your LD
then I would suggest you use a Laser Diode TEST LOAD.

If you have time and an endless supply of money for replacement
Lasers then don't use a Laser Diode TEST LOAD... You might get
lucky.

BTW... 95% of the Test Load Threads/Posts on this Forum say to
use one....:thinking: But the choice is ultimately yours...

Jerry

NKO29 · Jun 12, 2013

Thanks for the feedback, i will take your advice and wait for my test load parts to come in the mail

now i gather that it's not NECESSARY but it is alot better practice to do this test.

ApexProxy · Jun 12, 2013

I wouldn't say it's necessary, I would say its required. You simply don't build lasers without testing your drivers. Its like finding a 5 gallon can of gas on the sidewalk and just dumping it into your car. It's clearly gas so it should be fine... right?

The one exception to this rule would be purchasing a driver from Lazeerer because he tests the drivers himself so you could probably get away with not testing them from him IMO.

chipdouglas · Jun 12, 2013

for buck/boost drivers yes, for linear drivers no.

Michael.

ApexProxy · Jun 12, 2013

I have had exp even with linears being wrong. They were some of the major ones used around here as well. I won't say which ones just because it was an isolated event but the point is it does happen.

Just4FunReally · Jun 12, 2013

The only time it's acceptable to not use a test load is when its acceptable to lose your diode. If you think that losing your diode is an acceptable risk, then by no means do you have to use a test load.

Admittedly I made my first LPC-815 laser without a test load, and nearly killed it. The voltage when I first turned it on (using a DIY driver with LM-317 regulator) was too high, and the laser was very bright for an instant and then dimmed to what it should be. I got lucky that my diode lived, but I test load all of my drivers now.

ApexProxy · Jun 12, 2013

Lol, well anything goes when money isn't an issue.

chipdouglas · Jun 13, 2013

ApexProxy said:
I have had exp even with linears being wrong. They were some of the major ones used around here as well. I won't say which ones just because it was an isolated event but the point is it does happen.

You should say which driver so future buyers can make an informed decision, that is unless you know it was user error. I've done about 10 and have never had a problem/error.

Michael.

Just4FunReally · Jun 13, 2013

chipdouglas said:
You should say which driver so future buyers can make an informed decision, that is unless you know it was user error. I've done about 10 and have never had a problem/error.

Michael.

It is no longer an issue. The manufacturer made good in all of the instances and hasn't had an issues since, and since we respect the manufacturer, we'd like to keep them in good standing on the forums. If it had actually been a serious issue, you'd see the review and company forums riddled with info about it. We're not trying to be secretive, just polite. I hope you understand. :beer:

Things · Jun 13, 2013

chip is right, I've never used a test load on linear drivers and it's fine. Boost/buck drivers operate at high frequencies and need to be able to sense the output to keep stable. But a test load will work on linear drivers too, so it's a good idea to get one if you intend on working with buck or boost drivers later.

ryansoh3 · Jun 13, 2013

If you're tight on budget, you can get the parts here: Heavy Duty Test Load Kit for Laser Diode Driver 3000mA | eBay

I personally bought the parts individually and it cost me $0.80.

Blord · Jun 13, 2013

ryansoh3 said:
If you're tight on budget, you can get the parts here: Heavy Duty Test Load Kit for Laser Diode Driver 3000mA | eBay

I personally bought the parts individually and it cost me $0.80.

That is right. You can make a very simple testload with the cheap components. I wouldn't advise to keep the load more than a few seconds on for a high current driver. The components get hot very fast.

Just long enough to see the measurement on the DMM.

Why test load... Is it necessary?

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