The Big Green Thread (I'm gonna regret posting this in the morning)

[macona]

No, no. That is aluminum. 6061-T6 with mist. I avoid copper. I have used these end mills for copper boat electrodes for my vacuum system and it leaves a very nice finish.

[chad]

I use milk, I buy it by the drum.
http://youtu.be/h83xaOLrE_k

chad

[mixedgas]

Optical mounts made late yesterday evening for the optics which need size adapters to 1" and for the crystals.
Here we go,,,,

Steve

[steve-o]

Oh Boy !!!!




____________

[macona]

I use milk, I buy it by the drum.
http://youtu.be/h83xaOLrE_k

chad

Must be nice to have rigid tap...

[mixedgas]

Crystal mount #1 being tested tomorrow at work, I suddenly need 266 at work and thanks to Macona, have a doubler for 532. . Its almost exactly the same dims as my 4x4x5 Vandate,. Fortunate circumstances.

I'll learn all about angle tuning of crystals tomorrow.

Steve

[mixedgas]

HIGH SIDE CURRENT SENSE FOR 12V DC SOURCE and UP TO 25 AMPS

See Attached.

ALL RESISTORS 1% TOL .25 WATT UNLESS OTHERWISE STATED.

DO NOT ATTEMPT TO BUILD WITHOUT USING PRECISION RESISTORS FOR R1, R2, R4, R6, R7

One percent resistors are not expensive, on the order of 17 Cents each in DOD standard values.

R3 and R12 must be Kelvin connected.

The goal of this circuit is to avoid using expensive, quirky, current sense chips. Digikey parts have been ordered for a test of this portion of the driver.



Steve

[shrad]

Steve, you're the one!

I could calculate this, but do you have indications on gain and bandwidth for the output?

If I'm not wrong, a P channel mosfet between the sense and the diode, driven by the current sense output, would make a nice driver, but it needs to be tweaked to work in the mosfet driving range

[-bart-]

Maybe time to resurrect solarfire's initiative ?

http://www.photonlexicon.com/forums/...read.php/15974

[mixedgas]

Steve, you're the one!

I could calculate this, but do you have indications on gain and bandwidth for the output?

If I'm not wrong, a P channel mosfet between the sense and the diode, driven by the current sense output, would make a nice driver, but it needs to be tweaked to work in the mosfet driving range

Your not wrong, but that is only a small fraction of the board.

There needs to be a few more things, soft-start, overcurrent trip, UVLO, and a time delay, and a way to confirm all needed power supplies are there, plus a shutdown means to gently short the diode before turning off. 450$ diodes do deserve some serious protection.

On the other hand, I'm tired of designing in parts that go away in 3-5 years on "END OF LIFE", so this gets built with discretes.

I have complete, ready to go, proven, analog circuits for the TECs. However there will only be at most one small TEC in this 3W laser.

I'm hoping to not have to fine tune the diode temps. I have 8 watt green lasers at work that keep the big diodes at +/- .01 C. I do not see such a need for that level of precision.


Steve