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Frequently Asked Questions about the High-Speed Photography Kit

Read the entire Flashkit Article for free, with pictures from Make Magazine!

Order the High-Speed Photography Kit Online.

See also the High-Speed Photography Kit Manual and Assembly Instructions.

  • Can I order the Flashkit directly from Quaketronics?
  • How do I turn off the flash controller?
  • Which way do I turn the delay knob to get maximum gain?
  • Which way do I turn the delay knob to get maximum delay?
  • How do I get the strobe to trigger on a splashing drop of water?
  • Why does the flash fire all by itself?
  • How do you use light triggering?
  • What have you photographed other than breaking balloons?
  • How fast is the flash in the disposable camera?
  • How fast is the flash in the SnapShotII?
  • How do I connect my electronic flash to the flash controller?
  • How can I make my own cable to connect my electronic flash to the flash controller?
  • I am having trouble getting the flash controller to trigger on the light from a laser pointer. What am I doing wrong?
  • Does the beam need to come straight into the detector, or can it come in at an angle?
  • Can I get a picture of a bullet in flight with the flash kit?
  • Can I have a copy of the CAD files for the flash kit?
  • Do you sell a bare board for the flash kit?
  • Where can order the high-speed flash kit?
  • Where can I see pictures that have been taken with the kit?
  • What if I have questions that are not covered here?
  • Can I order the Flashkit directly from Quaketronics?
    No, please order them from here.
    How do I turn off the flash controller?
    Remove the cables from the flash controller. The microphone may remain connected, but remove the other cables.

    Which way do I turn the delay knob to get maximum gain?
    Clockwise.
    Which way do I turn the delay knob to get maximum delay?
    Clockwise.
    How do I get the strobe to trigger on a splashing drop of water?
    Start with a block of wood such as a 2"X4"X6". Drill a hole in it that is a little bit larger than the diameter of the microphone. Put the microphone into the block of wood. The shaft of the microphone can stick out from the block of wood. Slip a nail in alongside the microphone. This jams the microphone against the block of wood, to get a good acoustic contact. Stuff some cotton in the hole behind the microphone to isolate it from outside room noises. If necessary, put a piece of tape over the hole, also. Put this block of wood with the mike in it underneath a plate with water in it. Turn up the gain on the flash controller all the way. Now when the drop hits the water in the plate, the sound will trigger the flash.

    We dropped the liquid from a height of about four feet. We used a fixture to hold an eye-dropper to make the water drop. The fixture is another block of wood that has a hold drilled in it. The hole is slightly larger than the eye-dropper tube but smaller than the eye-dropper bulb. The fixture allowed us to precisely position the drop of water, which was important for getting good focus. The fixture also allowed us to use a high enough height to get a loud enough splash.

    Getting good focus was tricky. We put an object right at the expected splash-point and focussed on that, and then removed the object for the picture. The object was a lego.

    Actually, we weren't satisfied with the way that water looked for our splashes. We wanted a bowl shape with a crown of droplets. I wanted to use glycerin, but I couldn't find any, so we used anti-freeze instead. The anti-freeze (ethylene glycol, mostly) has higher viscosity than water, and alcohol has lower viscosity than water. Adjusting the ratio of these two liquids allowed us to adjust the shape of the splash. We also added food coloring.

    I was tempted to use syrup so that we would have all-edible chemistry, but I didn't want to clean up the mess. Milk is also reported to be interesting.

    In the picture below, we used two SnapshotII strobe lights. If you look closely at the highlights, you can see the shape of the strobes in the water drop.

    Why does the flash fire all by itself?
    Continuous firing in optical mode can be caused by flourescent lights or other flickering light sources. Continuous firing in audio mode can be caused by background noises such as fans, clothes dryers, etc.

    A low battery can also cause continuous firing in both optical mode and audio mode.

    How do you use light triggering?
    The flash trigger has a photosensor. The photosensor is active whenever the microphone is disconnected.

    The photosensor responds to fast changes in light. This change can be a light turning on or off very quickly.

    Your camera flash is an ideal for triggering because it is fast and bright. To use the flash trigger this way, disconnect the microphone and point the 'Eye' of the flash trigger in the general direction of the camera flash. Connect either a Snapshot or the disposable camera flash to the flash controller.

    The controls for the 'Eye' work the same way as the microphone. The gain controls the sensitivity of the eye and the delay provides up to about 0.01 seconds of delay. For triggering the camera flash, use minimum delay and a low gain setting.

    The eye will also be triggered by flourescent lighting, since this type of lighting is actually flickering on and off faster than most people can see. Use a low gain setting to prevent the eye from being triggered by ordinary flourescent room lighting.

    A laser pointer can also be used to trigger the photosensor. Mount a small, inexpensive laser pointer on a block of wood to keep it steady. Shine the laser pointer on the flash trigger eye. When the beam is broken (say, by a falling object) the rapid change in light sensed by the eye fires the flash. Turning the beam on will also trigger the flash.

    The flash controller is not very sensitive to the light generated by a laser pointer, so use a high gain setting in this application. If you have flourescent lighting, reduce the room lighting to prevent false triggering.

    The flash controller is sensitive to light from an ordinary flashlight. Use a flashlight to experiment with the sensitivity of the controller.

    What have you photographed other than breaking balloons?
    • Sparks (discharging a capacitor)
    • Lighting a match
    • Breaking a board
    • High-speed launch of a wet paper towel
    • A splash from a drop of liquid
    • Breaking glass
    • Falling objects in midair
    How fast is the flash in the disposable camera?
    The flash in the disposable camera lasts about 600 microseconds, or about 1/1700th of a second.
    How fast is the flash in the SnapShotII?
    The flash in the SnapShotII lasts about 120 microseconds, or about 1/8300th of a second.
    How do I adapt my electronic flash to the flash controller?
    Use the 3/32" (2.5mm) output marked "Flash", not the 1/4" (6.35mm) output. You can use an adapter to adapt the 2.5mm connector to a 3.5mm connector. Then use a 3.5mm to PC cable. 2.5mm to 3.5mm adapters can be found by doing a Google search on Philmore 542A or AA221 2.5mm 3.5mm.

    You can also make your own cable.

    How can I make my own cable to connect my electronic flash to the flash controller?
    You can modify an existing cable, or create a new cable with wires and a 2.5mm phone plug. You can buy a 2.5mm plug connector from Mouser. Here are the part numbers:
    171-3304 This is just the plug, no wires
    172-2103 This is the 2.5mm plug with two wires attached. This is easier to use.

    The polarity is important! Our flash trigger output is a 2.5mm phone jack. The center conductor (tip) gets the positive trigger voltage, and the outer (shield) is ground. If you can rig this up to your electronic flash, it should work fine.

    If you are going to modify a cable, cut off the end that you are going to connect to the 2.5mm connector. Spread the wires. This step is tricky if your cable is coaxial. Turn on the flash and measure the voltage across the two wires with a voltmeter. You should see a positive voltage reading. If you see a negative reading, reverse the wires to the voltmeter. The wire attached to the positive end of the voltmeter should be connected to the center conductor of the 2.5mm phone plug, and the other wire goes to the outer shield.

    If you don't have a voltmeter, or the measurement doesn't make sense, you can just try making the connection one way, and if it doesn't work, reverse the two wires.

    I recommend that you buy a new 2.5mm mono connector, or find a 2.5mm mono cable that you can modify, rather than cut up the cable that we have provided. That way you can test the flash controller and make sure that it still works with our cable and the disposable camera. But if you want, you can use the cable that we sent, and void your warranty!

    I am having trouble getting the flash controller to trigger on the light from a laser pointer. What am I doing wrong?
    The most sensitive setting will be high gain in a dark room. In this setting, the flash controller is also sensitive to the flickering of flourescent lights.

    A red laser pointer should work best. The phototransistor is most sensitive at the infra-red end of the spectrum, and least sensitive at the blue end. Many laser pointers are not very bright, actually. Try waving a flashlight past the controller. If that works, you know that the sensor is functioning.

    The flash controller is only sensitive to relatively high-speed changes in light. Many lights do not turn on or off quickly enough to trigger the controller. Of course you can interrupt a laser beam very quickly, so this should be fast enough.

    I got a very cheap (<$10) laser pointer to work. I took apart the laser pointer, hooked it up to a DC power supply, and mounted the laser diode in a block of wood. The block of wood gave me a way to hold the pointer. I had problems getting the flash controller to fire unit I had solid mounting for both the sensor and the laser pointer.

    The DC power supply modification allowed me to increase the voltage a little bit to get a little more power, since my laser pointer was only barely bright enough to work. A fresh battery in the laser pointer may have a similar effect. If you have access to a brighter red laser pointer, you can try that as well.

    Behind the hole in the flash controller there is the light sensor, which is a phototransistor. Look in the hole to see the lens.

    Picture of phototransistor with lens detail

    The lens focuses the beam on the phototransistor. Line up the brighest part of the laser spot on the lens.

    Does the beam need to come straight into the detector, or can it come in at an angle?
    The beam should be perpendicular to the plane of the front panel where the hole is located. The angular response of the sensor is such that you get 90% of the best response within 10 degrees of perpendicular.

    polar graph of sensor angular response

    Here is a graph of the angular response. This graph is from the datasheet for the photosensor, which is a QSE114 made by Fairchild.

    Can I get a picture of a bullet in flight with the flash kit?
    For a high-velocity bullet, you will need a higher-speed flash than the one included in the flash kit.

    Pellet through bulb
    Photo by cell15design, used with permission.
    Picture hosted by flickr.com.

    Here is a pellet from a pellet gun. This picture was taken with the Quaketronics flash controller and the flash built from the provided disposable camera. Click on the picture to go to the flickr site, where you can see a higher-resolution version of this picture.
    Can I have a copy of the CAD files for the flash kit?
    No, we don't offer CAD files for the flash kit. To build your own, I recommend building and testing one circuit stage at a time. The schematics and material lists are on the Make site. The theory of operation is in the flashkit article.
    Do you sell a bare board for the flash kit?
    No, we don't sell the bare board. The schematics and material lists are on the Make site
    Where can order the high-speed flash kit?
    Order a high-speed flash kit here!
    Where can I see pictures that have been taken with the kit?
    There is a pool of pictures on flickr set up for pictures taken with the flash kit. Most, but not all, of the pictures in this group were taken with the equipment in the kit.
    What if I have questions that are not covered here?
    Please send your questions to
    support@quaketronics.com.

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