TTL, Lasers, and Shutters for Variance...

Okay heres where I'm at:

I'm currently in the process of building a laser projector. I have my scanners working, and the beam table I engineered, but the problem is with getting the CDRH required shutter to work. I'm using a 12vdc 900mA power supply, a 12vdc ledex solenoid, a 12vdc 2amp relay with a 5vdc 42Ohm coil.

When I apply 3vdc @ 100mA to the relay coil, it snaps and the shutter works, although when I connect it to the TTL line of my DAC card, the relay does not work.
I have also tried a 30vdc 2amp relay with a 4.5vdc 145Ohm coil, with the same result.

Any ideas?.. Thanks for the help..

TTL isn't enough power to run a relay, and actually you can damage some digital outputs on some things by doing that. If the source is able to sink that much current (which I very much doubt but it should be in the specs somewhere for whatever you're using) you need at least a diode across the coil to keep the induced current from going backwards and blowing up the controller. What you need to do is use the TTL output to turn on a transistor which turns on the power to the relay. (You still need the snubber circuit on the relay) Or better yet use a solid state relay which you might be able to connect directly to the TTL output. But make sure you get one that controls DC, some are meant specifically for switching AC only.

Good luck, and post pictures!

Just a note. If you are building this for your own amusment then you do not have to install any safety measures. Read the Sticky Posts for further understanding.

Umm.. That kind of helps. I am no electrical engineer, so this is a little hard for me to figure out. I'm interested in going the Transistor way, but I'm not sure what I need. The second relay that I talked about is a soild state relay with a diode on the coil. This is the last step for me, before I apply for a variance from the goverment, so any help would be awesome!.. thanks guys..

...and you do not need a variance(license)

This is a class IIIb to class IV laser laser projector, and it will be used in nightclubs, it will need a shutter and a variance.

I have an OEM laser for this projector, a 100mw class IIIb that I'm using to test this setup, and I will be purchasing a 1 watt DPSS in the near future.

So far I have a Beam Table with 10 arperatures, and a 30kpps scanhead. The beam table is analog controlled, by a Chaser controller, and the XY are hooked up to a computer.

This is a pretty wicked setup, and it looks great, but I need the shutter to work.

Here is a free program that I do believe you'll find useful called Scan Guard Lite.
http://www.laservisuals.com/

Thanks for the program link, this looks really useful!. Also, I talk to the company that sells the software I'm using, and it seems that my problem may be related to a bad DAC card. They are sending me a replacement. I checked my relays against the blanking output of the dac, and it worked fine. I guess my shutter DAC is dead.. Oh well, another week set back.. /ubbthreads/images/graemlins/frown.gif

I'll have pictures of the projector once I have it completed.

My custom Beam table and controller work awesome, I just need to buy some 10r / 90t beam splitters, to replace the FS mirrors on the arperatures, so I can get the most out of the controller. Time to order from edmunds again /ubbthreads/images/graemlins/smile.gif