FlexMod P3 Analog/TTL Laser Diode Driver

[Heavyen]

Package received, thanks

[drlava]

Law, a switching power supply is perfectly fine, even suggested due to the smaller size. I use these on my system as well.

[lulighttec]

Andrew,

It was great to meet you this last weekend, and even get to chat a little bit. I think eventually I'm gonna need a few of these (probably 3). I did pull apart that laser and find the +/- leads (the one DJMatt traded me at SELEM), so I think it shouldn't be too hard to wire to a flexmod, after which it will need a power supply. I'm also thinking about getting one of the modules you were showing in another thread, so it will probably need one too. Anywho, try to set aside 3 for me when you get a chance, and feel free to make any helpful comments you might think of.

Thanks,

Newlin

[mspencer1]

I currently have a homebuilt RGB laser projector and am using an e-bay scanner from China and a few drivers that run on line voltage (AC). I purchased a Flexmod P3 to begin replacing these lower powered drivers. I have an old P2 that has been damaged and I really liked it. However I noticed that with my current drivers, if I unplug the modulation input from the laser control board the laser stays on continuously. With the Flexmod driver I have to give it 5v of modulation for it to turn on. This makes me think that when I plug it into my control board it will be OFF when it's supposed to be ON and vice-versa. Do some drivers sense that there is no TTL input connected and turn on?

[mspencer1]

Does 0v always =OFF and 5v always =ON with all laser drivers?

[catalanjo]

Shit NO!

Some are just shorted for full on, open circuit full off (or exactly the opposite).
Some are 0vdc = on 5vdc = off
but MOST (NOT all) are +5vdc full ON, and zero vdc full OFF.

I opto-couple mine so that I can adapt to all types just by rewiring.

Hope this helps!

Cheers

[mspencer1]

Do you mean to use something like a NAND Gate to invert the signal?

[catalanjo]

Do you mean to use something like a NAND Gate to invert the signal?

No just pull up or pull down resistors as required !

The led side of the opto-coupler (high impedance) can relax to an ON state or to an OFF state.

You choose, depending on the pull up/down resistor. (using zero or 5vdc from controller)

The photo-transistor side can: not conduct (no led lit), short across (led lit), pull up or pull down, (using zero or 5vdc from projector) which kind of covers every combination.

They are also relatively linear for analogue modulation (depending on which opto-coupler you use).

The main thing to bear in mind is that module should turn OFF if connection is unplugged for safety reasons!

Cheers

[mspencer1]

I did some testing tonight as well as some research. I found out that my laser drivers TTL inputs float high therefore they are always on when modulation is unplugged. I tested the modulation outputs of my laser control board and found that it's an analog signal where 1.0 volts is OFF and 5 volts is full ON. I wasn't aware that the TTL on my drivers floats high when not plugged in. I just wanted to make sure if I had 3 of the Flexmod drivers that it would work correctly and now it sounds like it will.

[catalanjo]

I did some testing tonight as well as some research. I found out that my laser drivers TTL inputs float high therefore they are always on when modulation is unplugged.

That is what is somewhat dangerous to say the least !

Needs pulling down, then back up when input signal is applied thats why I use opto-couplers that can supply the current required, which the controller output might not be able to do without buffering (which is a hassle).

Cheers