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ArcticMyst Security by Avery

First power supply

phenol

phenol

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Thats a 300MHz scope, but when i limit its bw to 20 MHz the loop doesnt pick any noise whatsoever...
I am not saying that this or that chip is bad per se, it is the layout and component selection that make the difference. For instance, inductors, even those shielded ones, radiate detectable amounts of hf noise, as do high current traces. If the fb loop of one such driver passes under or close to a power inductor, it may render the whole design inherently unstable.
as a precaution against switching transients, i have soldered 0805 100n caps directly on the leads of my laser diodes.
 





Cyparagon

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Sigurthr said:
You're absolutely right, but I don't think it is a common issue for the kinds of loads one usually encounters.
Click to expand...

I disagree. He's already said he intends to power drivers with it. I'm not talking theoretically here; I've had it happen several times. Common issue or not, he asked about it.
 
scumbagatheist

scumbagatheist

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uaM5NHC.jpg


Not for nothin' guys, but here's a pic of my rig, running stably with the driver nailing it's setting straight from Mohrenberg. It did switch into CC mode as I cranked up the current. The PSU was preset to 6.5V prior to adjusting.
 
Lazerbeak

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Sigurthr said:
It is definitely doable for under $50 or so. There are several methods, but I'm fond of the DIY approach;... this can easily supply 300A at 5V.
Click to expand...
My brain hurts,:thinking: I don't even really understand what you said there, but that was awesome Sigurthur :) You high voltage guys you.

That's a sweet PSU SBA. Looks like definitely a necessary tool for the serious enthusiast. Thank you for sharing.

phenol said:
.. it may render the whole design inherently unstable.
as a precaution against switching transients, i have soldered 0805 100n caps directly on the leads of my laser diodes.
Click to expand...
Hi Phenol, I'm sorry for the dumb question, but all the deep electronics talk is Greek to me. Using capacitors to stabilize your laser diode current is the gist of what I got. Please share if you are willing, what switching transients are and how the capacitors are able to overcome them. It sounds like an excellent method to improve the voltage to the laser diodes. Thank you :)
 
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Sigurthr

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Switching transients are sudden very fast changes in current and voltage that react to a property in all conductors called inductance. When current changes rapidly it causes inductance to try to fight back by creating very high voltages. These high voltages will blow out a laser diode. Capacitance fights inductance, and also high frequency voltage changes see a capacitor like it is a shorted piece of wire. So by placing a capacitor right on a laser diode with as little conductor used as possible you minimize the inductance and provide a route for high frequency transients to go through that is outside of the laser diode.

Oh and thanks for the compliment!
 
Lazerbeak

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You're welcome :) Thank you for sharing your knowledge. Very cool, like applied quantum theory. So if I understand correctly, the leads of the capacitor are just touching the positive wire to the diode. How do you know how big a capacitor. Does to much conductive material leech power to the diode? Thank you in advance. BTW, the tesla coil lasing the hene was too cool for words :bowdown:
 
Lazerbeak

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If possible, it would be great to see a picture of a driver set up with the capacitors in place as a reference guide. This seems like a different conversation, compared to the traditional driver configuration threads. Really awesome thank you. :san:
 
scumbagatheist

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Lazerbeak, pardon me if I'm wrong, but it sounds to me like you could benefit from the same online electronic circuits course that I am using. It's completely free, and basically an C.C. level electronic engineering course.

Check it out if you like. Here's the link
I'm treating like a course, so that I get as much as possible out of it.
 
phenol

phenol

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in this case the LD is some distance away from the output of the driver. The purpose of this capacitor is to bypass the brief high-freq switching spikes that may be arriving at the leads of the diode. 100nF may not be enough to smooth out power-up slugs of poorly designed high current drivers, sometimes even 2uF is not enough....
Because i have them, I also slip ferrite beads on the wires leading to the laser diode. Those present high impedance to fast transients.
 

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scumbagatheist

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Man, is that UGLY! At least it's working for you! I'm afraid I will be waiting until I finish the section of capacitors and induction before I go through this kind of trouble. If my PSU is gonna be a bitch with a driver, I've got batteries to back me up.
 
phenol

phenol

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it will get even uglier if you spill solder all over the prongs of the diode
 
scumbagatheist

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Of that, I have no doubt. I've suffered enough at the hands of solder blobs (or is that my hands?).
 
Lazerbeak

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scumbagatheist said:
Lazerbeak, pardon me if I'm wrong, but it sounds to me like you could benefit from the same online electronic circuits course that I am using. It's completely free, and basically an C.C. level electronic engineering course.

Check it out if you like. Here's the link
I'm treating like a course, so that I get as much as possible out of it.
Click to expand...
You don't match your name at all SBA ;) The thought of a electronics course of some sort has been coming up a few times :whistle: Thanks, it looks really good. rep once the system lets me :)
 
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