TTL and analog can live together?

[Steve Milani]

Hi all guys.

Surelly this is a poor question....
I have an unused TTL red unit CNI >400mw at 650nm. I would like to use inside one of my RGB analog projectors. Using the existing control signal (analog), may I add the TTL red unit and drive both them safety way or not?

Any advice welcome

Greetings and excuse me for so stupid question.... better to ask before to do!

[LaNeK779]

i'm in for a stupid answer as well, hope someone knows the correct way to do this

ttl needs either 0 or 5 volts. analog is happy with anything between 0 and 5. would it be possible to use the analog signal to drive a solid state relay and supply 5 volts directly to the ttl input? will the relay be fast enough to capture the modulation speed? or maybe some sort of semiconductor is better suited for the job

[badger1666]

why not just try and see, most ttl lasers come on at a lot less than 5v
the ones i had came on @<2v.
it should be fine, the only problem i see is it dropping out before the other lasers on a fade for example .
it wont hurt to try it

[Steve Milani]

OK..OK...

I know (enough) how analog signal works and TTL also...
I well know that, when analog signal voltage is (example) 1.5V the analog unit will be "slightly on", instead the TTL unit will be still "off" as it need a full 5V to light on....
This means that I will have a full power from both lasers only when voltage will be 5V.

Then I say better...

My (poor) question is the following:

Is it possible to combine a TTL unit with an analogue unit and to drive both them, together, with the analogue signal, without to make a trouble? (burn out a driver card or a laser diode or something worst...).

possible answers:
1) Yes!, it's possible whithout any problem for laser diodes, drivers, etc. etc.
2) No!!! You're crazy?!?!? It's impossible 'cause you surelly make a trouble with diodes, drivers, etc. etc.
3) Yes, It's possible BUT..... (please to explain shortly reasons and limitations)


Thanks alot once more for any suggestion and infos

Steve

[badger1666]

i would go with answer 1,

your ttl laser will not need 5v to come on you will find it will most likley come on at 2v or just above that, either way it wont hurt the laser diodes or drivers

[Steve Milani]

Thanks Badger!
Your thought agree with original mine. Should be any problem.

As I written into my first post, always better to ask before to do

I will try and then I will let you know a.s.a.p.
Thanks!

[badger1666]

Thanks Badger!
Your thought agree with original mine. Should be any problem.

As I written into my first post, always better to ask before to do

I will try and then I will let you know a.s.a.p.
Thanks!

hi steve the only thing to check or adjust is if the ttl laser is positive trigger or negative trigger ,there should be a switch on the driver to change from + or - drive,like on laserwave lasers,
when you power up your ttl laser is it on all the time ?
if you have any trouble with the laser being on all the time and there is no switch on the driver swap the +- blanking wires around, it wont hurt anything i have done it before with a cheap chinese laser i had
if you not sure what i mean let me know and will try to help

[Stoney3K]

Mixing TTL and analog won't hurt. Both accept 0-5V modulation signal, but TTL lasers will come on at a certain threshold voltage where analog lasers will vary in intensity in a more linear fashion between 0V (off) and 5V (full brightness).

Most TTL's have a certain range where they will operate 'somewhat' analog, due to the characteristics of the driver transistors, but for most applications, they're on-off only. Most (if not all) laser show software lets you select analog or TTL modulation for each channel independently.

Playing back an analog show on a TTL laser will not damage anything, it's only going to look different. Playing back a TTL show on analog lasers will look as it should.

[Steve Milani]

Thanks guys for tips and advices

Just for record...
TTL unit which I would move to the analog RGB proj, is already installed into a RGY TTL projector controlled by ILDA. When I turn on projector, red and green TTL diodes are always "off" both, as well same way of all analogue diodes into my other RGB projectors.

I'll keep you informed about progress.

Cheers

[mixedgas]

Proper TTL logic switching thresholds are 1.6V for a low, and 2.4 for a high. TTL's input impedance is low and is saturation dependent.

Now, if the Chinese laser designer followed the design rules is another question.

Steve