ttl is wrinkling my brain

[pow3r]

i've been working off and on again on my laser cutting cnc for a while now. initally i was going to use a 445nm m140 diode, but i'm now playing around with a s06j 12x, with a g2 lens.

i'm getting some good cuts, but i haven't been able to get the ttl working, it's always on (even with the TTL in disconnected).
With the m140, and ttl turned off there was always a dim beam from the laser, with the 12X it's a lot brighter (i guess because it needs less voltage/current to lase)

the driver i'm using is this driver, which someone else had had success with, with a 12X
405nm Laser Diode Driver FOR 50mW 500mW LD W H Current Adjustor TTL Input | eBay

i'm using a PC controlled relay, which triggers the 5v into the TTL, so i could just use that relay to switch the 12v into the driver, but i'd rather have the TTL working correctly, as switching the 12V off will turn off the fan i have over the diode.

can anyone suggest antyhing i can try. or suggest a TTL enabled driver i can use with a desktop power supply (so 12v/5v in) to power a 12x?

 

[Things]

Put a pulldown resistor on the + TTL wire to the ground wire, something 1-10K will do fine. Most cheap drivers are designed to be turned on with no TTL signal, and if you're using a relay, the TTL signal will just be floating.

 

[pow3r]

so between the + and ground of the 5v TTL in, before the connect to the board?
(in this shot is the white and blue wires on the right of the driver?)

i'll give that a shot, but yeah, it's annoying that the TTL circuit doesn't do much to stifle the laser, behaves more or less the same with anything plugged into the TTL or not.

 

[Things]

Yep, should fix it.

As for always giving a bit of light even with TTL off, that's sometimes an added feature of drivers to keep the current right under the lasing threshold so they can switch on a bit faster.

 

[pow3r]

cool, thanks heaps man, will try that out

 

[james211]

This was a while ago, did you ever resolve?