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TO-18 / TO-3 808NM Diodes

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Lamarr

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Hi Guys,

I am no expert, but I am looking to wire up multiple 808nm 300mw laser diodes to a single heat sink (was going to power these with one larger CC driver, in series, but each diode will now have it's own Aixiz constant current driver) but I'm wondering as I will have one solid heat sink, am I likely to have any shorting issues that would blow the diodes?

I understand the TO-3 Mounts are more likely to be electrically insulated is that correct?

Thanks in advance!

Lamarr
 
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Alaskan

Alaskan

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I was going to do something similar at one time and with the diodes I was going to use, it was a problem. I was going to have to find a way to electrically insulate the case of the diode from the heatsink to run several of them in series. Most drivers can't be used for multiple diodes because their maximum total voltage is too low, but tomorrowssystem, an ebay seller, does sell one which can run at a higher voltage allowing you to string more diodes in series. You will need to contact him to ask, I don't think he has that one listed on ebay.

The work around I was going to use to allow me to have one heat sink for several diodes was to wrap each diode with a very thin sheet of heatsink material to DC isolate them from another: 100x 100 x 0 5mm Silicone Thermal Pad Sheet CPU Computer Chip Heat Sink Heatsink | eBay

Beyond that, I'd need to check the info of your particular laser diode to see if it is insulated or not from the case to give you more of an answer.
 
VisibleGreen

VisibleGreen

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Laser Project said:
I was going to do something similar at one time and with the diodes I was going to use, it was a problem. I was going to have to find a way to electrically insulate the case of the diode from the heatsink to run several of them in series. Most drivers can't be used for multiple diodes because their maximum total voltage is too low, but tomorrowssystem, an ebay seller, does sell one which can run at a higher voltage allowing you to string more diodes in series. You will need to contact him to ask, I don't think he has that one listed on ebay.

The work around I was going to use to allow me to have one heat sink for several diodes was to wrap each diode with a very thin sheet of heatsink material to DC isolate them from another: 100x 100 x 0 5mm Silicone Thermal Pad Sheet CPU Computer Chip Heat Sink Heatsink | eBay

Beyond that, I'd need to check the info of your particular laser diode to see if it is insulated or not from the case to give you more of an answer.
Click to expand...

LP you can have your heatsink anodized and that will electrically isolate the modules from the heatsink
 
DashApple

DashApple

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if they are the 2 Pin TO-3 diodes then the pre made thermal pads will fit fine as you will most likely have to insulated them from each other as the cases are usually diode +
 
L

Lamarr

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Thanks guys, I actually decided to go for parallel wiring (although finding a driver wasn't an issue as I found a 50v variable constant current driver), so would the diode still need insulating? if so will the silicon pads transfer enough heat to maintain a long duty cycle/life span?

The only problem I can see with this, is that If I'm using the TO-3, I would have to use nylon bolts in case voltage is leaked via these?
 
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Lamarr

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Also the laser diodes I am yet to purchase them, so how would one tell if they are insulated? I am going for cheap bulk lots from alibaba or alike...I am using around 150 of them!
 
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Lamarr

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Looks like normal To-18 would be insulated wiring in parallel, if I were to put them all on one heatsink I shouldn't have a problem can anyone confirm that please?
 
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lazeristasUVISIR

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Lamarr said:
Also the laser diodes I am yet to purchase them, so how would one tell if they are insulated? I am going for cheap bulk lots from alibaba or alike...I am using around 150 of them!
Click to expand...

Get a datasheet for the laser diode! That must be your source about its pins.

As for a parallel connection: don't drive at full power then. LDs are individuals and they'll take different currents at the same voltage, and for some it might be too much.
 
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