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Thread: Bought a Laserworld 250mW greeny

  1. #11
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    Hi Greenalien, skies are clear as yet tonight so not the beam I had last night but helluva range now. 20 Miles at least. Will probably change as the firework smoke builds up later.

    The 555. I just connected output pin 3 to the TTL wire and used the 555 in bog standard astable mode at around 10 Hertz to give a nice flashing effect. Resistors 1k, 22k and a 10uF cap'. I'm a little bit cautious as 10Hertz is pretty near Alpha rythms and it seems to have an hypnotizing effect if stared at too long.

    As well as the flashing effect I'm hoping it gives the diode a longer life as it's 'only' rate at 5000 hours.
    A lovely childhood. Just me my mother and the voices.

  2. #12
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    Hi 450nm,

    Thanks for the 555 info - I'll have to try it. Did you power the 555 from a separate source? Do you know if there is any danger to the laser PSU in shorting the 2 ttl wires together, or should there be a resistor - e.g. 1k - between them?

  3. #13
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    I'm not sure what you are doing GA. The TTL is active high so shorting the wires together should put the laser into threshold mode (low power). Applying 5 Volts should then make the beam bright.

    Yes I feed the 555 and the die4drive from a common 7805 regulator.
    A lovely childhood. Just me my mother and the voices.

  4. #14
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    Main thing I want to achieve is to drive the TTL blanking from a standard ILDA socket. First question was how to use the TTL connections from the laser PSU, looks like that is 5v on, 0v off, so I can test that with a 555 as previously discussed.
    Seems like there are 3 possible connection options to the ILDA socket -
    a) Pin 13 (shutter) and pin 25 (ground) or
    b) Pin 6 (Green +) and Pin 19 (Green -)
    c) Pin 6 (Green +) and Pin 25 (ground)
    The first 2 options would give a 5 volt range but the second option will have the wrong ground reference; however, if the TTL black is not internally grounded, perhaps it would be OK to connect to the G- pin?
    The 3rd option is only 2.5 volt range but has the correct ground reference - will this be enough to switch the laser on/off - I've always thought of TTL as being 5v on, 0v off but I know this is a simplistic view!

    (I'd rather use the green control signal if possible as I'd like to keep the shutter option as a safety feature. I know this is an analogue signal but if I am just using 2 states, it should be OK)

    Any comments appreciated! TIA

  5. #15
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    Sorry GA way above me. I'm only a nooby. No idea what a ILDA is yet. I may be wrong but think TTL threshold is around 3.5V
    A lovely childhood. Just me my mother and the voices.

  6. #16
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    Thanks anyway, I'll move this query to the appropriate forum.

  7. #17
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    If you have a single-colour laser, you can connect the modulation to pin 3 (intensity / blanking) and pin 25 (ground) and then whatever colour the frame is made with in your software your laser will display it. If you connect to the Green signal and display a frame your projector will only display the green parts!

    Hope this helps.

    Matt.

  8. #18
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    Cool

    To expand on that, there is Intensity + (pin 3) and Intensity - (pin 16) on the ILDA connector. It's actually a differential signal. You can wire it either way, so if you have an oddball laser that uses +5 volts to turn OFF, you can still make it work. (Reverse the leads)


    The Red, Green, and Blue color signals work the same way. They have positive and negative components, and they're differential signals too. So when you have an RGB projector, you can wire the individual blanking leads for each laser to the corresponding pins. But as Matt said, with a single color laser you use the intensity signal, not the color signal. (Leave the shutter pin alone - that signal is for the shutter only, and the shutter is open whenever you are scanning. It will not blank the laser properly.)

    Adam

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