Infrared "Shooting Gallery" for Wild West Birthday Party

Discussion in 'The Projects Forum' started by slickwillie, Apr 6, 2016.

  1. slickwillie

    Thread Starter New Member

    Apr 6, 2016
    3
    0
    My daughter's 6th birthday is coming up and the theme is the Wild West.

    I'd like to make a "shooting gallery" which uses an IR gun to shoot targets. The targets would have IR sensors, and when struck, would do something (fall down, light up, etc.).

    For simplicity purposes, I was thinking of using a repurposed TV remote control as the IR source for the "gun". For the targets, my limited research has led me to using TSOP1738 sensors as the "targets".

    Note, that I have zero experience with IR, and limited experience with circuit design.

    I purchased what I thought were TSOP1738 sensors online as well as an assortment of 3mm and 5mm LED's that came with resistors. It turns out, the sensors were SM0038's (which I think are essentially the same thing, they seem to function the same way at least?).

    Following schematics I found elsewhere online, I was able to cobble together an SM0038, an LED (with resistor), and a 5V power source. The LED lit up continuously as I expected, then when I aimed a TV remote at the SM0038, the LED flickered.

    It's my understanding that the SM0038/TSOP1738 (when powered) delivers from its output pin whatever voltage it's receiving. When it's hit by 38kHz IR, it drops that voltage to zero. The TV remote delivers 38kHz, but in "bursts" which is why the LED appears to "flicker".

    For the shooting gallery, I'd like to design a target that when shot by an IR light flips a relay. The relay would make something mechanical happen (perhaps releasing a spring-loaded latch so that the target folds down on itself).

    I've read that I might be able to use a BC547 or BC557 to trigger the relay. My problem is that I think the TSOP1738 would make the relay "chatter" so quickly that a mechanical device would not have time to release.

    My research has led me to believe that I can eliminate the "pulsing" of the TSOP1738's output by using an RC circuit, but I'm not sure on the specifications or design of one.

    I'd like to make the targets as simple as possible. I've never used breadboards or arduinos, but if that's the only way to accomplish this, then I'm open to suggestions. Ideally, I can just solder some components together.

    For the gun, I am planning to use a repurposed TV remote housed in a PVC enclosure. I discovered that if I force the IR light from the remote's IR LED to go down a longer (12" long; 3/4" diameter) tube, then the "aim" of the remote is much more precise.

    Thoughts on designing the targets and gun much appreciated. I have 2 weeks, so I'd like to mock up a prototype as soon as possible. I'll need time to order parts online, too.

    thanks!
     
  2. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,128
    266
    Could work!

    1) The IR receivers like pulses of 38 khz, not a continuous signal- stick with the TV remote as a transmitter as it does this for you naturally.
    (make sure your remote frequency matches the RX units- there are several different carrier frequencies used)

    2) You may need to attenuate the IR output, either by using a resistor to reduce the LED current or an optical filter.
    The reflected beam will trigger the sensors readily if its too powerful.

    3) If you take the pulse output from the sensor, you could drive a charge-pump circuit, then use a comparator to threshold the output. This eliminates the "chatter" problem you noted.
    This setup would give you some margin to reject spurious triggers - in favor of solid input signals.
    This would yield a simple analog solution to the problem.

    4) it's all gonna be about the optics- creating a beam collimator to make it very directional, maybe a tube with an array of internal baffles to suppress reflections off the tube walls?
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    I was happy to be able to operate 3 IR beams 20 ft. long, 1 ft. separation with out cross modulation.
    Just tried out 3 mW. red laser & 2 cm. dia. CdS sensor at 10 ft. Used a red filter over cell. Room was lit with 5, 40 W lights, 3 are LED. Hits were reliably detected on ohmmeter. Is this a big enough target for kids ?
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    While looking for laser modules & CdS cells, found both, & also found laser target kit , C6739, $ 7.5
    at Electronic Goldmine.
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    Bernard likes this.
  6. slickwillie

    Thread Starter New Member

    Apr 6, 2016
    3
    0
    Thanks for everyone's help!

    I ordered some of the laser boards to test out.

    Now for making a "laser gun"... I am thinking I can just use a standard laser pointer. However, I don't want players to be able to just hold down the button and sweep to hit the target. Thoughts on how to limit the time the laser is "fired"? Basically a switch that engages temporarily, but for a set duration regardless of how long you hold the trigger. The laser pointers I've always seen "fire" for as long as you hold down the trigger. I want to send a pulse each time the trigger is pulled to avoid sweeping. The duration doesn't seem like it would matter, as I'm guessing the sensors above will pick up the laser instantly.
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Maybe a 555 timer to give a 100msec + pulse and a lockout time of about 5 sec ? No time today but maybe Monday.
     
  8. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Use a NO snap action switch to add some feel for a shot fired. Once fired , 10 uF cap. takes a second or 2 to recharge enough to fire again. One k R discharges cap. to 0 V. Three alk. AA or AAA might work, was tried with 5 V supply. 3 almost dead AAs seem to still give a good flash. Laser rifle 00000.jpg
     
  9. slickwillie

    Thread Starter New Member

    Apr 6, 2016
    3
    0
    Could you go into more detail how this works? Is a snap action switch just a momentary switch?
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Yes. More later.
     
  11. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
  12. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Post # 11 switch will work but will not have much audible , feel snap. I found one that seems to fill the bill, All Electronics CAT # 147, other lessor ones, 176,175, 227, & 237. Also found a 1/4 in. CdS photo cell.
    Operation: The 10 uF C starts fully charged; when SW is pressed, the charge on the C is dumped thru the LASER & partially thru 1 k R to fully discharge C. When the SW is released, C fully recharges in about 3 sec., ready for next shot.
     
Loading...