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Calling all FAPpers - FAP800 - precautions and driving advice

Alaskan

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Robert, I've been eyeing some ytterbium fiber lasers on ebay, prices always high, or the equipment suspect as being something pulled out of the trash somewhere and listed on ebay. I would also be interested if someone here has had a chance to work with one, or owns one.

Paul, I did enjoy burning some cardboard with one of these FAP's, but not my reason for buying it.

Here's a photo of the collimation lens I used in the photo's shown on page one of this thread, it came out of one of those 473 nm medical DPSS units which I sent you, it is screwed into that splitter module on the front of the unit the fiber cables go into and come out of. It's really not an IR lens, as you are aware, but also is without AR coating, so can be used at IR anyway. I don't know how much the back reflection can cause a problem, Mike had one of his units get a fried FAP output due to a back reflection somehow, but mine have never failed, yet. There is a ebay seller in Ukraine listing one of these lenses right now for close to 100 dollars, listing it as an IR collimator, BS! It wasn't made for that.











You can see what the high mRad of the FAP is with this 12.7 mm diameter collimation lens, 15 feet away and the spot is as big as my hand. Near the output of the lens the beam is only a very few mm wide, but sure gets wide fast a few feet away. Looking at these pictures again today I've come to think the output might not be fully collimated, look at how tiny the beam is leaving the lens in photo #3.
 
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Junkers

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Great info guys.

I had a gander at ebay last night after reading your comment Alaskan. I found an ASTRON VS-50M for a decent chunk of change and decided to have a look on youtube to see what's inside. Turns out not too much other than a huge transformer, some TO-3s, and the respective control ICs + filtering caps, which has me wondering whether I should build something myself. Even if I go the route of using a high end DC-DC converter like Paul's or Styro's I'll still need to source 40-50A from something preferably stable ( I would prefer to stay away from batteries). I recently tore down an old 200A TIG welder which had some hefty components inside including a decent transformer, a huge diode bank, a pair fo 400A IGBTs, and the heat sink to go with them. I'm in two minds about building my own versus buying one. I have a variac here and I should really make use of those components I feel. I could be exposing myself to a lot of problems as you can guess.

I also found this review of the DC-DC drivers I've bought. I'm still interested to see what can be achieved with these even if I don't connect them to my diode package. In the video he illustrates a single unit producing up to 250mV Vpp under 12 - 15A of load which is obviously not tolerable but I shall see how much I can reign them in by. I do have a scope and a current clamp.
 

Alaskan

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Regarding the Variacs, I built a 200 A 13.8 VDC power supply using the core from a high current one, taking the slider off, the original winding then became the primary and the secondary was created by wrapping the core with welding cable to produce the low voltage I wanted, then rectified with some huge stud mounted diodes which bolted to a heat sink, filtered with a lot of capacitance and added a large number of pass transistors in parallel for the output.

I used to own a couple of Astron power supplies, not sure how low a voltage they adjust down to, I seem to remember they won't go all of the way down far enough, but maybe I am wrong. Also, the duty cycle is greatly reduced when the voltage is turned most of the way down because the pass transistors used are dissipating all of that excess voltage as heat.

Edit: Found this link and the specifications, these only put out 10 amps continuous at 5 VDC, at 2 VDC, probably far less. Also, for testing you want to be able to adjust the voltage from about .75 or 3/4 of one volt and then adjust up towards 2.0 VDC, not have it bottom out at 2.0 VDC which is very close to the voltage these FAP's are run at for full power output, max 2.1 VDC:


Here are the power supplies I use, found them on ebay too, but they will spike over voltage when first turned on, if you have a diode hooked up to it then, it's fried. Yep, I'm repeating that point, worth repeating.

edit: These are both switching power supplies, I didn't want to pay what it would cost to ship a heavy power supply which uses a conventional transformer, rectification and filtering to me here, at these current levels, they are boat anchors.



Above, don't let this photo angle fool you on ebay, they are very long power supplies, see below. It's this form factor, or a wide one when it comes to this amount of current.

 
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DashApple

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Nice Info , I need to look into getting a better CC driver , I have used two M8 bucks @ 7A each for 14A for a red fiber diode but its an expensive way to get higher currents , I have a 20W 940nm fiber coupled diode that needs a driver too

P1010579 by TwirlyWhirly555, on Flickr
 

Alaskan

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Dash, I like it, a water cooled fiber laser. More photo's if you can :) What do you use it for? Optlasers might have a driver for you $$$

These switching power supplies branded as Sorensen can be found on ebay fairly cheap: https://www.ebay.com/itm/SORENSEN-DCS8-125E-DC-POWER-SUPPLY-8V-125A/223340041100 - but again, probably spike when first turned on (even if the voltage is turned all of the way down). I believe Cyparagon had something similar for sale on ebay for awhile, but a bit older.
 
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Junkers

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This is a question I probably should of asked sooner but what is the acceptable level of voltage ripple for a FAP 800? The article I referenced in my first post stated that transients as low as 25uA can damage the device.
 

DashApple

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Thanks : P , I don't use it for much as its a pain to focuses due to the large beam divergence . I'll take a look at the drivers , two black bucks for 80USD isn't to bad for 16A given the size of the driver though I did use two external low value resistors to help with current balance as I want sure how the two drivers would play together in parallel

P1010573 by TwirlyWhirly555, on Flickr

This is about the best I can get the beam with the optics I have , don't know enough on the optics to get the right ones xD
 

Alaskan

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Dash, when you write red fiber diode, what wavelength is it? At first I thought you meant deep red, as in IR, but with this photo, looks like 638-670 something nm.

Junkers, I went back to look at the article:



My understanding is they are referencing reverse current transients. This is an area I need more understanding, maybe someone can help both of us with this question.
 
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paul1598419

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Robert, I've been eyeing some ytterbium fiber lasers on ebay, prices always high, or the equipment suspect as being something pulled out of the trash somewhere and listed on ebay. I would also be interested if someone here has had a chance to work with one, or owns one.

Paul, I did enjoy burning some cardboard with one of these FAP's, but not my reason for buying it.

Here's a photo of the collimation lens I used in the photo's shown on page one of this thread, it came out of one of those 473 nm medical DPSS units which I sent you, it is screwed into that splitter module on the front of the unit the fiber cables go into and come out of. It's really not an IR lens, as you are aware, but also is without AR coating, so can be used at IR anyway. I don't know how much the back reflection can cause a problem, Mike had one of his units get a fried FAP output due to a back reflection somehow, but mine have never failed, yet. There is a ebay seller in Ukraine listing one of these lenses right now for close to 100 dollars, listing it as an IR collimator, BS! It wasn't made for that.











You can see what the high mRad of the FAP is with this 12.7 mm diameter collimation lens, 15 feet away and the spot is as big as my hand. Near the output of the lens the beam is only a very few mm wide, but sure gets wide fast a few feet away. Looking at these pictures again today I've come to think the output might not be fully collimated, look at how tiny the beam is leaving the lens in photo #3.

It has been quite some time since last I worked with the laser in this unit. The collimating optics, if my memory is still good, stink and I went looking for something else to get a collimated beam out of the 473nm unit. The beam splitter has been used by some for their raman spectroscopy, but I haven't gone in that direction at all. I'm sure you could do better than these optics for your FAP projects.
 
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Alaskan

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I have some lens assemblies with the correct AR coating, but they are made to mount a fiber with a clip holding it tight, need more fibers with an SMA on one end.
 

Hemlock_Mike

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Alaskan --
I'll try posting my pix again. The Bottom pix is the FAP with TI driver. The cells are under. The other pix is my
schematic for the TI PS. I'm using the Fiber optic cable to blur the dots in the beam.

That 50 Amp current supply regulated on the (-) side which might be good since the FAP is (+) chassis. It
could easily follow the TI supply both being of small size. I missed my chance to buy some 0.001 Ohm resistors!
Then again, the TI supply regulates on the (+) side ?!?
Mike
FAP Schematic.jpgFAP-1.JPG
 
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CurtisOliver

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Great thread, subscribing. I too have a 50W FAP. It is their integrated package (FAP-I) I've only ever ran it past threshold. Never had a power supply capable of high amperage at 2-2.2V.

Edit: Mike, great to see you. (y)
 

paul1598419

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Great thread, subscribing. I too have a 50W FAP. It is their integrated package (FAP-I) I've only ever ran it past threshold. Never had a power supply capable of high amperage at 2-2.2V.

Edit: Mike, great to see you. (y)
What about the supply for your new 532nm 4 watt laser? That should supply the kind of current, or at least more, that you are looking for. My 1300 mW 532nm one has a +5 volt supply at 15 amps.
 

CurtisOliver

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It probably is capable but I wouldn’t chance trying it tbh. I’d rather see it power 4w of green than 50w of NIR. :p
 

paul1598419

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You can also get a SMPS that outputs +5 volts at 50 amps for not much money. That can be used to power a driver for your FAP.
 




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