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FS: ***Selectable test load up to 3A (assembled or DIY kit)*** IN STOCK!






Z

zhivko

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I found following in literature:
Test Load*
A common method to test the driver is to connect a regular silicon rectifier diode to the driver output. Here has to be paid attention to the junction*capacitance*of the diode. Only fast recovery diodes (or similar) have a low parasitic*capacitance*as laser diodes have. To achieve reasonable test results, the parasitic elements of the test diode and the connection must be very similar to a laser*
diode approach. Regular silicon rectifier diodes have a junction*capacitance*of several microfarads and are not a suitable test load! The use of these diodes will yield in incorrect current measurement at the pulse edges!

Can you comment this?
Does bridge rectifiers you suggested have LOW capacitance?

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Z

zhivko

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Yes my laser diode is CW type but to use it with CNC and regulate power I use PWM power pulse on diode itself.
So my pwm on my diode is 10kHz.
To simulate possible voltage spikes at transition do you think I should think of low capacity rectifier bridge?

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Tmack

Tmack

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Got my test load. Very nice work. Drivers are great too. Thanks so much.
 
jimdt7

jimdt7

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Any chance you'll have them in stock by next week? :thinking:

Jim
 
The Lightning Stalker

The Lightning Stalker

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zhivko said:
Yes my laser diode is CW type but to use it with CNC and regulate power I use PWM power pulse on diode itself.
So my pwm on my diode is 10kHz.
To simulate possible voltage spikes at transition do you think I should think of low capacity rectifier bridge?

Sent from my Nexus 5 using Tapatalk
Click to expand...

The GBPC3501 should work well enough for testing. As long as there are no big overshoots
on the scope at powerup, I think you are going to be fine. The big diodes can take some
abuse, unlike the ones we work with here much of the time. You are going to have a
capacitance on the output of the driver anyway to tame the aforementioned overshoot. Some
final testing should be done once the actual laser diode has been attached anyway.
 
jimdt7

jimdt7

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That's good to know! :beer:

Jim

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Tmack

Tmack

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Mine has been getting it's use lately. Love how easy it is to use. Throw some alligator clips on and boobam. I also made a little rig to select one or two cells so I don't have to break out the power supply every time. Super convenient
 
Z

zhivko

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The Lightning Stalker said:
Don' t use a resistor. Use instead a current sense shunt. BR5FB10L0 is a good part number for your
application. At 11.5A, your meter will read 115mV. It is rated 5W, so you will be able to safely
measure current up to about 22.5A continuous using that. Intermittently even more

Use the diode bridge rectifiers in my previous post. There is a even schematic posted if you follow that
first link. Get 12 of them just in case they are a little on the low side. The last one can either be
connected in the center as in the 3V example, or the same as the rest. You will know when the current
level starts getting close to your 11.5A target. Just measure the voltage drop across the diodes to get it
as close as you can.
Click to expand...

Hi, I made dummy load with diode bridge as you suggested. There is no resistor in series with diode, but I have shunt resistor in my 10A current driver.
However dummy load doesn't eat any current... How is this possible?
jytymeme.jpg

How do I know that? Heat sink is cool as the summer beer ;)
What's wrong?
Rectifiers are the one you suggested.

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Jufran88

Jufran88

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Hey Guys the latest batch just arrived in the mail!! I'll be PMing you guys individually as I only have a limited amount this time. I'll go in order of who PM'd me or posted on here. More will be coming!! :beer:
 
The Lightning Stalker

The Lightning Stalker

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They do look like they're connected in series. I only count 11, so it may not quite reach 10.5V @ 11.5A.
It looks like the problem might be reverse voltage (that is assuming red positive and black for negative).
They should be "backwards" with neagative going into + and positive into the - terminals. When all else
fails, double check the continuity of the solder joints and use the multimeter's diode test mode to check all
the diodes.
 
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