Blown diodes and questions about the Badpip Quad driver

[-bart-]

ok look we all make the hot swap mistake once. OUCH you burned you hand on the stove learn not to do that. When you put a diode in or take one out keep it shorted until it is conneced and then remove the jumper. This eliminates any possible spike from any source. Second, put a lasorb on each diode chain and it will help you a lot. Third, You could though I have not seen it done build a soft start circuit into the power supply. That could be as simple as a large value cap across the power supply. Fourth, running at 24V is running on the hairy edge of the drivers parts ratings. You would be better to use more driver and lower voltage. Putting that much "Vf" for lack of a better name on the driver stresses the driver.

I had a cascade failure of all my diodes and drivers using p3flexmods after I put a diode in backwards while running off 12V. I think it took out my blue and then somehting went nuts in the power supply and an osc feedback into the whole thing and killed it all. You might try putting a scope and looking for parasitic osc around 110 Mhz. This can and does happen if the driver doesn't have suppression for such osc..

Get one more driver card and run off 12V. Put two diodes on each chain, add lasorbs to each chain, put a soft start on the power supply, look for parasitics and you should live a nice photonic life. Forgot. You can also add ferrites to the power rails near the driver and bypass 0.1uf caps across the rail near the driver (the usual filter). This will suppress osc in the power rail.

Attached isa softstart and a filter. These are from oakleysound and are not original thought. Should work well.

Robvdv is putting 4 diodes in series per driver, so 24 volt supply voltage is just right.

I would advise against a lasorb per chain, lasorbs are designed for a certain Uf matched to the diode, not to multiples in series.

A linear PSU would be ideal, but would be beefey @24v/9A.

I would advise against adding "a large value cap across the power supply" if its a switchmode.
Many manufacturers advise against this, or (specify a limit) in their applicationnotes.
And real hf-oscillations pass right through it.

[robvdv]

Thanks very much for the help, gents. I've clipped off all the capacitors. It seems to start up and shut down much mores smoothly now in terms of brightness spike. Thanks also for the information, Thomas. Your driver has been great to work with so far.

If anyone's curious about the project it's on Facebook here: http://www.facebook.com/FindYourself2012

Basically it's a cymatics sound to light machine that'll project patterns like these onto a 15m diameter inflated dome:

[swamidog]

that is *lovely*.. please tell me more.

Thanks very much for the help, gents. I've clipped off all the capacitors. It seems to start up and shut down much mores smoothly now in terms of brightness spike. Thanks also for the information, Thomas. Your driver has been great to work with so far.

If anyone's curious about the project it's on Facebook here: http://www.facebook.com/FindYourself2012

Basically it's a cymatics sound to light machine that'll project patterns like these onto a 15m diameter inflated dome:

[robvdv]

Cymatics is this: https://www.google.com/search?hl=en&...mg.AwHs40kfvdU

I use two sound cards bonded together under Linux to form a virtual 12 channel sound card. The channels are:
1-3 speakers vibrating the water lens
4-9 XY galvos, one galvo pair per colour
10-12 RGB intensity

I use CSound http://www.csounds.com/ to play tones to the 12 channels. I haven't really started to drive the device properly, but I've been getting patterns like this:





It'll be projected from inside an air inflated hemispherical dome. The pattern will be visible inside and out the dome. Air pressure will be maintained by a revolving door airlock.


Here's my project last year:
http://www.photonlexicon.com/forums/...inated-obelisk

Afrikaburn is good fun: http://www.afrikaburn.com/. It's the largest Burning Man event outside the US and if you're ever down south you should pay it a visit.

[swamidog]

you raise the bar on awesome projects. i would be all about coming over to play if the other side of the world wasn't so far away. your work is very inspiring.

Cymatics is this: https://www.google.com/search?hl=en&...mg.AwHs40kfvdU

I use two sound cards bonded together under Linux to form a virtual 12 channel sound card. The channels are:
1-3 speakers vibrating the water lens
4-9 XY galvos, one galvo pair per colour
10-12 RGB intensity

I use CSound http://www.csounds.com/ to play tones to the 12 channels. I haven't really started to drive the device properly, but I've been getting patterns like this:





It'll be projected from inside an air inflated hemispherical dome. The pattern will be visible inside and out the dome. Air pressure will be maintained by a revolving door airlock.


Here's my project last year:
http://www.photonlexicon.com/forums/...inated-obelisk

Afrikaburn is good fun: http://www.afrikaburn.com/. It's the largest Burning Man event outside the US and if you're ever down south you should pay it a visit.

[robvdv]

Thanks, that's very kind. I feel like a complete noob here chatting to you all. I greatly appreciate the guidance.

[Displaser]

I feel like a complete noob here chatting to you all. I greatly appreciate the guidance.

Please don't, you're doing some amazing work & your project looks great! I'd like to know more about your "Water Lens" if you will tell us about it.

I'd love to see this in the dome. Thanks for sharing this with us.

Greg

[chad]

I agree, Really pretty images. Keep up the great work.

Chad

[dilbert]

Loose the caps... period..... that's your problem.

If your concerned with a certain effect that can happen running a series string of diodes @ high modulation speeds with some drivers use 10nf ( 0.01uf ) per diode.

[sugeek]

Could not upload the images.

I thought I had that problem earlier, the upload link is not highlighted click the text and it will work.