I'm Almost Ready For 20W!!!

[KapHn8d]

Am I the only one that heard the Empire theme when I saw SBA's pic?

 

[scumbagatheist]

:crackup:

Kap, you always keep me entertained! We'll have to meet up at the next TEXLEM or something.

 

[scumbagatheist]

I think I'll title this one, "I'm not F-ing around any more" or "$h!t just got serious"

Look at the beautiful shine on this diode heatsink from Mrcrouse! He does such great work. And he packs things so securely, it aggravates my arthritis to rip it all open! (that's an endorsement)

Look for great things to come from a collaboration of SBA Lasers and Mrcrouse in the coming months. :shhh:

 

[Bionic-Badger]

Is the surface of that sensor meant to handle that kind of power?

 

[Trevor]

Is the surface of that sensor meant to handle that kind of power?

Well... the datasheet says it can handle 20W with external heatsinking. But it also states that the supply should be up to ±18V... and if I recall correctly, that means you could measure a maximum of 16W - not 20W. Something about the signal always being 2V less than the input, at a maximum.

That being said, all I'm looking at is this simple, poor excuse for a datasheet. There's probably a whitepaper somewhere, but I've no idea where it is.

http://www.ophiropt.com/laser/pdf/20C-SH_20C-A_20C-UAU.pdf

Trevor

 

[scumbagatheist]

If you run a 36V PS w/ split rails at 18VDC for each rail, you can measure up to 20W. Based on other 20W Ophir heatsink designs I've seen, mine should be more than capable of cooling the sensor.

 

[djQUAN]

You can't get 20V output from 18V supplies. It may be 36V total but the signal is ground referenced which means output can only swing to plus or minus 18V. But since the op amps inside the head aren't rail-rail, the output can't swing right at the supply voltages. There is a 2V drop so it can go to only 16V which is 16W.

 

[Speedy78]

Its not like ike you will need those extra watts to measure any handhelds you have or ever will have

Im still waiting on you to build a readout display so you can stop using that DMM haha

 

[scumbagatheist]

That's why I said I would have to use a 36V power supply. These heads are out there measuring 20W, the design is made to measure 20W..I don't know why this 16V issue keeps coming up. I'm not trying to get 20V or split 18V or 20V...Just wait for the finished product.

 

[Speedy78]

Its recommended max onput is 18V via the data sheet. With a loss of at most 2V in the head you get 16V. If you run 22V to it maybe you can get the 20W.

 

[scumbagatheist]

Speedy, This thing is being designed to handle my future endeavors with CO2 lasers.

As far as a readout goes, I still have much to learn about building the arduino, running the power circuit, etc...That's alot to take on while I am building so many lasers and designing a new line of lasers.

I can get by on the DMM until I can either find the time to build the LPM or buy one...I hate to go out of the box though.

 

[Speedy78]

You're going to need more than 20W for most CO2 tubes out there. Hahah. I like building my own things too but I was impatient and needed a meter.

 

[ARG]

As far as a readout goes, I still have much to learn about building the arduino, running the power circuit, etc...That's alot to take on while I am building so many lasers and designing a new line of lasers.

Arduinos come pre-built in all cases I think

 

[scumbagatheist]

Thanks, ARG...I still have not had the time to wrap my head around how to do your DIY ARG meter. I hate to say it, but I may just have to buy one with DL from you.

I just don't see how I am going to find the time to learn and build the DIY ARGMeter.

 

[djQUAN]

Sorry, I'm not good at explaining things in words but I'll try. If this still doesn't come clear, sorry, I just woke up

The op amps inside the head can swing its output to the plus or minus voltage minus 2V. Since the output is ground referenced (brown wire) you can only go to the plus or minus voltage. If you're using two 9V batteries, that would be plus 9V or minus 9V. Subtract the 2V dropout of the op amp's output stage, you get 7V maximum output swing.

Now, you're planning to use a 36V supply, which you will then split in two to get plus and minus 18V. So now the ophir output will be referenced to the new "ground" which is the midway or the "split" which is at the middle of that 36V supply. So now the op amps have plus and minus 18V supplies. With zero input, your output will be at the midpoint or split of the 36V. So you have 18V minus the dropout which results to 16V swing. To have a 20V output, you'd need plus and minus 22V rails or 44V total which is well beyond the max supply voltage for the op amps.

The 20W rating mentioned is for the 20CA-0.1-Y which has an 0.1V output per 1 watt input which would only need a 2V swing for 20W input. I'll try to dig up where I read it and link it here.

 

[ARG]

Thanks, ARG...I still have not had the time to wrap my head around how to do your DIY ARG meter. I hate to say it, but I may just have to buy one with DL from you.

I just don't see how I am going to find the time to learn and build the DIY ARGMeter.

PM me and I'll walk you through it if you want.

I've needed a test subject to explain things to such that I can write an effective "how to" tutorial.