Need suggestions for creating blanking from 5V ttl with non-ttl laser module

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09-18-2010, 05:35
michelrietveld

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Need suggestions for creating blanking from 5V ttl with non-ttl laser module

Attachment 19641Hello all, new to this forum so first let me introduce myself
Michel Rietveld age 39, been playing with lases since i got my first tube from a optical disc player which needed a cascade power supply.
Now i am currently working on an x-y r,g & b scanner.
Bought myself a PT-Itrust ILDA controller board from Phoenix Technology.
Have 2 x 30K mirror with driver attached and just for the fun a 200mW green laser pen.
I use I-Show software, interfaces through usb to my ilda interface.
Shows run smooth but as my laserpen does not support blanking i would like to create some sort of deflecting mirror to fade/blank the beam from the ttl blanking output of the board. Anyone done this before? I have a spare mirror and driver type G120DT which i would like to hook up to the 5V ttl output.
I have a picture on how to control the beam in combination with a 90 degrees mirror setup. See attachment.
Any suggestions or should i just invest in a laser module that has ttl steering build in?

Michel
09-18-2010, 06:32
mixedgas

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Depending on the amplifier for your G120, TTL should be just fine for Galvo blanking. See there are a few kinds of TTL used in the laser world. The real TTL switches at 1.6 and 2.4 volts. Fake TTL is high speed CMOS logic and switches from about 100 mv to 4.90 volts.

If you have "fake" TTL you will need a potentiometer to reduce the signal to your blanking galvo amp, and then you will be ready to go.

If you have real TTL, you may need a simple "LEVEL SHIFTER" circuit to develop enough swing for your galvo, but again, there may be enough movement in 0.8 volts of change for your application. There most likely is enough change in .8V for galvo blanking.

Good Luck, Steve

IF, and it is not likely, but IF you need a level shifter, here is a simple one:
09-18-2010, 09:27
michelrietveld

reply to steve

Depending on the amplifier for your G120, TTL should be just fine for Galvo blanking.

*warn So i just connect the 2 pin output of my controller card to the 4 ping galvano board, have to figure out which pins to connect.

See there are a few kinds of TTL used in the laser world. The real TTL switches at 1.6 and 2.4 volts. Fake TTL is high speed CMOS logic and switches from about 100 mv to 4.90 volts.

If you have "fake" TTL you will need a potentiometer to reduce the signal to your blanking galvo amp, and then you will be ready to go.

*warn Just checked on my scope, seems to be fake ttl from 0 to aprox 5 v what kind of potentionmeter value do you suggest?

If you have real TTL, you may need a simple "LEVEL SHIFTER" circuit to develop enough swing for your galvo, but again, there may be enough movement in 0.8 volts of change for your application. There most likely is enough change in .8V for galvo blanking.

Good Luck, Steve

IF, and it is not likely, but IF you need a level shifter, here is a simple one:[/QUOTE]
09-18-2010, 12:03
chad

As for the pot, really anything will work. 5k , 10k.

chad
09-23-2010, 12:54
hobbybob

Quote:

Originally Posted by michelrietveld

Hello all, new to this forum so first let me introduce myself
Michel Rietveld age 39, been playing with lases since i got my first tube from a optical disc player which needed a cascade power supply.
Michel

Hi Michel,

Your name suggests that it's very likely you are Dutch (or maybe Belgium) ?
Welcome on the PL forum, change your profile so people can see where you're from, that helps a lot in getting help from "local" people.

In November or December there will be a LEM in Ilpendam, organised by our (i still presume your Dutch) fellow countryman McCarrot. Joining us there, will get you lots of knowledge, you can share ideas and see what other people built/are using/designed etc.

Well... hope to hear more from you ?

Kind regards,
Dimitri
09-23-2010, 19:57
mixedgas

Agreed, 5K -10K would be just fine.

Steve
09-23-2010, 20:25
drlava

mirror blanking is cool in a nostalgic kind of way, but if you don't mind modding the laser pen you could replace its driver with one that accepts ttl control. I can think of one low-current one (good for pens) that I didn't make that costs about $6.
09-24-2010, 05:27
michelrietveld

Good tip, have been thinking about that also, i also have another diode at hand, salvaged from a very cheap laser show projector with stepper motors created figures (duh..) so i would like to give it a try with this one.

the drivers i on found, on ebay, that support ttl seem to be limited to 10K speed, will this be sufficient? and how will i be sure i don't overload the laser, for example, feed it too much current.

Michel
09-24-2010, 05:44
michelrietveld

I ordered the FlexMod P3 Laser Driver, why is no green lasorb protector availlable?
I will use this for the red and green diode i salvaged from a stepper motor driven el cheapo lasershow device

Michel
09-24-2010, 06:35
hobbybob

Hi Michel,

Until recently green was made from IR (808nm), nowadays you have also direct injected diodes, but most green is still made from IR diodes and crystals.
This IR beam is shot through 2 crystals ND:YVO or ND:KTP where one crystal makes the wavelength 1064nm and one doubles the frequency (so the wavelength is half that, being 532nm ie Green). (very simply said, i am not a physics professor)

So to protect your green you need a RED Lasorb (since the RED lasorb also protects IR diodes).
09-24-2010, 07:02
michelrietveld

so will a red laser ttl driver than also work for a green pen?
09-25-2010, 00:03
michelrietveld

1 Attachment(s)

nostalgic mirror blanking Question

so for the blanking part 1 i will try to use the blank/fading mirror approach
this is to be done by connecting a galvo amplifier to the 0-5v ttl 0(blank) 5v(laser) output of the pt-itrust controller.
As suggested i will use a 10K potentionmeter for tuning.

But, when i look at the amplifier schematic i am not sure where to present the signal to.

I have attached the schematic as a tiff file for the people who would like to take a look and share some advice. the galvo is a g120dt.
09-25-2010, 06:33
mixedgas

connect ground to Jp1 ground and JP1 -in, connect signal to JP1 +in.

Steve
11-08-2013, 07:52
JasonB

Level Shifter

Quote:

Originally Posted by mixedgas

See there are a few kinds of TTL used in the laser world. The real TTL switches at 1.6 and 2.4 volts. Fake TTL is high speed CMOS logic and switches from about 100 mv to 4.90 volts.

If you have "fake" TTL you will need a potentiometer to reduce the signal to your blanking galvo amp, and then you will be ready to go.

If you have real TTL, you may need a simple "LEVEL SHIFTER" circuit to develop enough swing

IF, and it is not likely, but IF you need a level shifter, here is a simple one:

* AHA! * Steve, this post just made me realize something I've been thinking about and trying to get working for over a year *retardo
I've been struggling with getting my blue laser to blank correctly for over a YEAR; the red and green work perfect. All lasers are different and chinese as well.
The red runs on 5VDC and shares my common +/- 5VDC power supply for my opamps, comparators, etc. , green runs on 120VAC and accepts the common 5VDC blanking just fine..
But that Blue....I have not been able to sort it out.... It requires a 12VDC supply and I've breadboarded comparators, inverters (as current sinking buffers), tried sinking/sourcing it's TTL input and only can get 'flakey' blanking response at best.. It drifts over time.

Maybe just sharing the 0VDC reference for the multiple power supplies is not sufficient, perhaps I should try that level shifter circuit and reference the blue laser's 12VDC supply to the transistors collector, set the pot, and see what happens.
I wonder if its possible this laser requires 'its own' power source to complete it's TTL input circuit ? Its hard to say without being able to look at a schematic of the laser.

Does it make we weired that I want to leave work right now, drive home, and breadboard this circuit ? ;) ** This could be the final tweak to my homebuilt RGB to make it work correctly! **
Steve you are THE MAN!

Steve this post is right along the lines of a previous post you made:

Quote:

Originally Posted by mixedgas

thread 13712

Chinese low cost blanking wants to see a current sink instead of a current source. Since most laser systems output a source, you need to add a simple NPN transistor to ground to "invert" the blanking signal, or use a TTL buffer chip between the laser software and the laser.

For some lasers, a 2n2222 with a 470 ohm base resistor is all you need. Emitter to ground, collector to the laser, base to the laser software via the 470 ohm. In some cases you may need a pullup resistor, perhaps about 1K on the collector to +5. Most lasers have the pull up, and the opamp in the FB3 is not good at fighting them. The FB3 meets the TTL specs, but the Chinese lasers can need more then 20 mA of sink to turn on, which is outside the limits of most opamps.

The Chinese lasers really want to be driven by a TTL totem pole output stage, but only in sink, they do not need the source side, so you need to fake one. Open collector TTL inverters are good for this, as are AC, ACT, HC or HCT series CMOS.

Steve

-Jason