I have made this driver circuit for my lasers but i want to add ttl modulation to them can anyone provide me with a schematic for making that driver have ttl inputs?

 

Which circuit?
This one? http://laserpointerforums.com/attac...de-laser-diode-driver-ld_driver_schematic.jpg

It has a 47uF cap across the laser diode. That would pretty much prevent using the circuit for modulation.

 

What if i remove the capacitor... its just to prevent voltage spikes... its not absolutely needed... i really want to be able to put ttl inputs on this

 

OK.

How much current and at what voltage does your laser diode require?

At what rate do you wish to modulate the laser light?

What voltages do you have available?

 

ok maybe there is another way to do this... how can i integate a 555 timer into this? all i am wanting to do is be able to turn it on and off at different rates... the driver is adjustable so i can tune it to output the right mA after the diode test load is attached.

 

OK, this is one way you could do that:

For the sake of simplicity, the 555 timer is represented by a box.