445 threshold current?

[norty303]

I've got the first of my 445's up and running, doing about 520mW @ 730mA through an Aixiz glass 405 coated lense.

However I'm having a bit of problem setting my threshold current on my flexmod. At 180mA I get quite a lot of light out still. At the moent I have it at 20mA and its still producing light! Is this right - do all diodes 'leak a bit below threshold, or am i just going to have to ramp it all the way down if i don't want any light spill?

[dave]

Yeah, thats pretty typical of 445nm diodes.. Time to install a shutter...

[chad]

I have found these to be pretty leaky at low levels. The big question is how does it look when scanning.

I would try out some test patterns and adjust your bias to a image and see what looks best. You just don't want some blue eeking out when fully blanked.

I have been worrying about this too. It will probally come down to a combination of bias setting and color tuning in your software.

chad

[norty303]

Hmm, no room for a shutter....... looks bloomin great scanned, and i don't do graphics anyway, so probably less critical for colour balance

[norty303]

Hmmm, actually i can get it to go off completely, but it looks like there is a little bit of signal on my FB3 line when it is idle as it comes back on when i plug in the modulation.

[norty303]

One other thing... is it ok to do fine bias adjustments with the diode connected?

The flexmod instructions say to disconnect and use a meter on the outputs, but what i want to do is just drop it down until the diode goes off.

Connecting and disconnecting every 10mA increment to see if it has gone off yet is just mind numbing, and probably not so great for the connectors either!

[neutrino]

One other thing... is it ok to do fine bias adjustments with the diode connected?

The flexmod instructions say to disconnect and use a meter on the outputs, but what i want to do is just drop it down until the diode goes off.

Connecting and disconnecting every 10mA increment to see if it has gone off yet is just mind numbing, and probably not so great for the connectors either!

I hooked mine up yesterday and after doing the initial setting setup with a multimeter I decided to tweak it with the diode connected. It didn't seem to have any adverse affect with my diode, however, I may have just been lucky.

Man these things look good. Waiting on some new scanners to make up a couple of new blue only projectors.

Can you measure the current whilst the diode is connected or do I have to disconnect it?

Cheers
Rich

[allthatwhichis]

I have not been able to find a way to turn it "on" and nt get any blue light out of it. My Kvant does seem to have the same "issue"... It looks like a built in soft start.

[Lexat8]

Evening,
I fiddled with my bias settings with the diode connected. Nothing went pop!

here's some crap video of a few tests I did

www.445fx.blogspot.com

Cheers

Lex

[kecked]

set the bias to 100 and that works well. Dr. Lava set mine for me and it works real well.