multi color laser project

Discussion in 'The Projects Forum' started by flare09, May 17, 2012.

  1. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    hey everyone, i need some direction.

    i have contacted many people to build this for me and everyone has dropped out of contact. so, i have given up, so if anyone has schematics to point me to to do this myself, please show me the way.

    or...if a little paypal electrons help for completed boards, it is available.

    i need a laser driver, three actually, that i can dim, i want to do this by lowering the current then pulsing the laser slower to appear even more dim. i wanted to stay away from the lm317 because i know there are more efficient ways, any schematics help.

    i need a charge circuit for two LiFe batteries from a standard wall ac to dc jack, i would like an led to show charging, and another to show fully charged but still plugged in.

    i need an led array to measure the amount of charge in the batteries in the form of 3 red, a yellow, 3 green and a blue leds.

    a driver for a pump and fan, i was thinking a resistor? but there has to be something better

    and a circuit to turn on an led when a certain temperature is reached near the laser diodes. so a temp sensor?

    the tricky part, i have to make all this smd so it'll fit inside the housing, which is 1.8 inch diameter circle, with 1 inch up and down

    i have almost all the power requirements, if anyone needs them.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,118
    3,042
    Well that's the challenge. Even the batteries must fit in that space? Really tough for a DIY. Do you need to actually make this, or just design it (big difference!)?

    I know there are folks out there working on laser-based projectors to replace those bulky tabletop projectors that business presenters lug around (been there, lugged that). You might be able to borrow some ideas from those, if you can find anything.
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    I'll do it for $10K USD.. :cool:
     
  4. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    Haha mcgyvr...take two zeros off that.

    And no that's just the space available for the board. I need to make it. I have the host and lasers and optics. I just need this board. Im going to print the board myself and reflow the components. I have looked but linear drivers are all I can find.
     
  5. rohitd

    New Member

    Jan 29, 2011
    14
    0
    to do such type of a work you need a custom fabricated IC see anyone who fabricates a few number f IC's in your locality. give him your circuit design. may be this could help or else i agree with mcgyyr about the difficulties involved!!
     
  6. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    I have already contacted several people, they drop out of contact. So im grabbing this project by the ferrite beads and making my own custom printed circuit board. I just need schematics and parts for the individual drivers.

    Like the fan, it runs at 5V, batteries are at 6.2V. Do I just put a resistor and drop it to 5V? Or a potentiometer? Can I use a LM317?
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,118
    3,042
    This may be the least issue of the project, but anyway you could just put 2 diodes in series. That would drop a consistent 1.3V or so. Of course they need to be rated for your fan current.

    Depending on the draw on the batteries, their state of charge, and the fan details, you might not need anything to protect the fan. It might take 6V safely.

    Oh, and a pot is great for controlling voltages with small currents. They're too expensive for controlling power directly.
     
  8. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    yes indeed it is the least of my problems. but if i wanted to turn the fan speed down i could use a pot to keep it at a lower speed right?

    so i found a thread on using a 555 to make a dc current from an lm317 based driver, modulate. is there a way to change the speed the diode is modulated, along with the current with two pots?
     
  9. wayneh

    Expert

    Sep 9, 2010
    12,118
    3,042
    You can use a 555 timer IC to build a nice PWM fan controller.

    You mentioned temperature control. Take a look at the LM35 thermometer IC; it outputs 10mV per °C. So you can just use a comparator with a voltage reference (set by you with a pot) to act as a thermostat. Link the output to a MOSFET, and you can drive a large DC load. I posted a "calorimeter" project in the finished projects forum that uses this approach. I had to use an op-amp to get tighter control, but you don't need that for normal applications.
     
  10. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    thank you so much :) i found stuff about the lm3914 too. yay lets start with eagle...i cant get my parts library to load. maybe im not sure how to search correctly? i just click drop part, then search right? it wont load the preset library...
     
  11. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You are not saying anything about the lasers' maximum current rating nor their Vf when operating, nor your supply voltage.

    Your space is so limited that unless your laser current is very small, power dissipation on the board will be a huge problem.

    Unless the laser current is very small, there won't be enough room for a switching supply solution.
     
  12. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    the diodes are rated at max: 445nm-1W, 635-300mW, 532nm-200mW. i found an ic that will work for me, the STCS2. im just having trouble finding a trim pot rated at 1 ohm. i have three of them on one board, i have a corner left for the temperature ic and room for all the connects, on a second board i will have the charging ic, and voltage reading/led array ic. obviously i am going to make the traces as wide as possible that supply to the diodes. but so far on pad2pad the three ic's fit
     
  13. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    Also I have 6.2V to pull from batteries. And the led array, and trim pots are going to be on a separate piece so I just need holes to solder ribbon wire. I can't find any rheostats sensitive down between 1 ohm and 66 milliohm. So I might have to make a rotary switch with different resistor paths on another board.. unless anyone knows where I can get a good pot under 1 ohm and and precision?
     
  14. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    What voltage are you planning on using as the supply?
    What is the typical Vf of the laser diodes at their rated current?
    You've given the wattage rating, but not the current nor Vf.
    The STCS2 is a linear regulator. Its' minimum supply voltage is 4.5v.
    The problem with a linear regulator is the power dissipation; Vdrop x current. You want to put three regulators plus a bunch of other stuff in a small space. It's going to get mighty toasty in there. You will have to have a way to get rid of all that heat.

    You wouldn't use a trim pot; you would use a fixed resistor to set the maximum current, and then use the PWM input to change the perceived intensity.

    I'll bet that you have made no provisions for the cooling.
     
  15. flare09

    Thread Starter New Member

    May 17, 2012
    19
    0
    the supply voltage is from 2 LiFe batteries, 6.2V. the blue is rated at 3.7V at 80 mA and up to 5.5V at 1.7A, the red 1.9V at 230mA up to 2.6V at 400mA, the green i tested to respond at 1.8V at 200mA and 2.2V at 380mA i didn't ant to push it harder because i didn't have it heatsinked.

    i have heat sinks to thermally glue on it and i have a custom radiator i built to water cool the diodes. the air flow is moving past all the circuit boards at a max 4CFM. so there will be enough cooling. the board is going to be copper heavy with a sink on the other side.

    i understand the resistor thing but i wanted to be able to dim the lasers then slow their modulation. it will allow for a more detailed color blend...

    i am taking into account heat. trust me
     
Loading...