Airgap Flash Manual
Contents
1. Flash Manual Version 0 7 October 20 2013 Lead Maurice Ribble Major Technical Contributors Alan Sailer and Paul Picot Table of Contents Safety Description Operation Specifications Maintenance Photos Top View Front View Back View Side View Bottom View Included Capacitor Discharge Stick Included Cables Left Internal View Right Internal View Top Internal View Top Internal Circuit Board View Flash Tube View Schematics system Level Schematic Flyback PCB Pulse PCB Safety DANGER HIGH VOLTAGE High voltage stored in an internal capacitor is LETHAL and may be retained for long periods To reduce risk of electrical shock disconnect power before opening the case and then the internal capacitor MUST BE DISCHARGED Never insert anything inside the case The three terminal power plug on this device makes use of the earth ground connection and that connection must be maintained to avoid electrical shock Sure the power outlet you are using has a proper earth ground If you are not Knowledgeable about safety procedures for working with high voltage you should never open the case Instead have it serviced by an expert in high voltage test equipment If you are familiar with high voltage device safety a capacitor discharge stick is included and you should always discharge the capacitor immediately after opening the case If the device is ever dropped it should not be turned on until it s been inspected Th2. 0 seconds Ground leakage 68 UA which is well within safe limits In the case of an open ground the case potential is 58 Vac which could be felt but is not dangerous Trigger lag In 26 test shots the high voltage trigger pulse averaged 3 7 0 3 microseconds after the input trigger extremes 3 08 and 4 55 us The actual arc followed another 7 3 2 8 microseconds extremes 4 76 and 11 95 us Measurement precision was 0 04 us Trigger current The trigger reliably fired at 0 5 mA current Short circuit trigger current is 20 mA Maintenance The Airgap flash requires periodic maintenance of the flash tube In our testing we found a oxidation build up that started to prevent reliable flashing after around 2000 or more flashes This number is highly dependent on the environment Humidity heat and air quality play a factor The image below is an image after 10 000 flashes and it was still working well Cleaning is necessary when the flash stops working reliably This can be extra flashes when it shouldn t be though this can also be caused by high humidity even with a clean flash tube or not triggering when it should The fix is to take apart the flash head and clean it To do this safely you must understand how to safely work with high voltage If you don t know these procedures leave this cleaning to an expert The Airgap flash maintains a high voltage even when it s off and unplugged from the wall You must use the included shortin
3. as mixture we breathe instead of xenon gas The main advantage of the using air is that it greatly shortens the duration of a flash Why fill the tube with air There must be some better gas right Actually Harold Edgerton who is widely acknowledge as a founder of flash photography did extensive experiments with various gases and found that for high speed flashes using standard air is actually one of the best gases because it gives a good compromise of short durations and moderate amount of light An added benefit is that using air reduces the cost of the manufacturing process so air is a very good gas choice Here a two examples of photos taken with flash that would not have been nearly as compelling if taken with tradition flash because they would have had motion blur Operation The typical use of this flash is for photographing high speed events To do this a camera is typically set to have a long shutter duration say 5 seconds in a dark room Airgap flash will provide all the light in a very short duration so shutter speed don t really matter Most often the Airgap flash will be used with a high speed photography trigger such as the Camera Axe The Camera Axe has various sensors to determine when a photograph should be taken and then it can trigger the Airgap flash at that instance From this point on any references to a high speed trigger will just be referred to as a Camera Axe since that is the trigger
4. ash Tube Flyback PCB GND is NESSOMN R1 1 H TR 2144401 RS Lak 5 GND GNO 1 DIODE ZENERPTH U 3 ZENERFTH DPHE GND mshilaastva Flyback Transtormer P 1 Heatsink 15 OL 11420 Jh 47uF of s 1N4 Pulse PCB DA 1144994 EC103M BT169 16 ACL IN_AC VO aA DUT N_AC_Gh OUT_GND IN_AC_GND OUT_GND OUT GND OO Trigger Transformer MB1PTH_LONGPAD MB1PTH_LONGPAD Primary TRANS_G O B 47uUF MB1PTH_LONGPAD I Secondary 5 61
5. g stick to discharge the large internal capacitor One issue that has happened in the past is humid weather caused the the airgap to either randomly trigger or continuously trigger Increasing the gap between the electrodes in the flashtube can help reduce this problem but in very humid environments this issue can t be solved You should target humidity levels of 50 or lower for optimal operation Photos Top View Front View Back View High Speed Air Gap Flash V1 Produced by Dreaming Robots LLC Line 47 63 Hz 90 132 VAC or 180 264 VAC Ships configured for 90 132 VAC operation Internal jumper must be changed to support 180 264 VAC Fuse 2 x20mm Fuse Maintain ground to avold electrical shock Read the manual before opening For indoor use only High voltage charge stored in an intornal capacitor ls LETHAL and may ba retained for long perlods reduce risk of elocirical shock disconnect power before opening case case and thon the internal capacitor MUST BE DISCHARGED NEVER INSERT ANYTHING INSIDE THE CASE Side View Bottom View 10 Included Cables Left Internal View 11 Right Internal View Top Internal View Top Internal Circuit Board View TE EA RE 13 Schematics System Level Schematic 120VAC Wall Plug Flyback PCB Pulse PCB rs 0 Red Button Case Ground Big Capacitor Fl
6. ing system tested with the Airgap flash The Airgap flash triggers like a standard low voltage flash and should be compatible with other triggering systems out there The controls for the Airgap flash are 1 An on off switch 2 Ared button to trigger a test flash 3 A BNC connector which has an included cable to connect to the Camera Axe There is also a standard Y threaded tripod mount on the bottom of the flash Make sure any tripod used can safely handle the weight of the Airgap flash Fire the flash no more than once every 30 seconds to give it time to fully recharge reduce ozone creation and keep cool Specifications Weight 9 Ibs 15 oz Dimensions 6 x 6 6 x 11 inches Input Voltage 90 132Vac at 47 63 Hz Input Current Under 2 Amps Light Duration e Time zero to peak 0 29 microseconds e Full width half maximum 0 55 microseconds e Full width 1 3 maximum 0 86 microseconds e Full width tenth maximum 2 7 microseconds Light Output With the diffuser in place this flash output is 4 stops below a small shoe mount flash at 1 16 power At ISO200 my test exposures required f 6 3 at 50 cm Its approximate guide number is 10 feet ISO200 Recycle time Recharges fully in under 10 seconds However it will can fire every second or less at a less intense flash which would lead to uneven exposures Robustness testing was done with 10 second recharge rate so it is recommended to fire the flash at no more than once every 1
7. is device is designed to operate with a power line voltage of 90 to 132 volts ac 50 or 60 Hz suitable transformer type voltage converter must be used for operation in regions with other line voltages Never place anything on top of the flash There are pressure sensitive components inside and the device requires good ventilation This device has been designed constructed and inspected with due regard to product safety However it does not carry Nationally Recognized Testing Laboratory certification It is the purchaser s responsibility to determine whether approval is required to use this device in their jurisdiction and to secure such approval if necessary The high voltage nature of this device generates ozone You should use it in a well ventilated area to prevent the buildup of this gas Description and Background Information This flash is called an Airgap flash because it uses air between two electrodes slightly over an inch apart and a high voltage to generate a spark This spark is what generates the flash of light A photographer can think of it as their own well controlled lightning bolt in a protective case The Airgap flash is designed to be an extremely high speed flash That is the problem the flash solved and it makes compromises in other areas to achieve that goal For those who want to photograph relatively slow events they should use a normal photography flash The Airgap flash is for those really high speed eve
8. nts where a normal flash leaves a blurry image To contrast the Airgap flash with a traditional flash nearly all photography flash units on the market today use flash tubes filled with xenon gas The advantage of using xenon gas in flashes is it generates a high quality light with a relatively low voltage hundreds of volts and low power The disadvantage of xenon based flashes is that the reason it generates a lot of light is because the xenon gas glows so these flashes have a relatively long flash duration for super high speed photography Some of the fastest commonly available xenon flashes have a duration of 1 30 000th of a second This Airgap flash has a duration of about 1 1 000 000th of a second This means the duration of the Airgap flash is about 30 times faster which is critical for photographing high speed events such as bullets in flight Below is an image comparing a photograph taken with this Airgap flash versus a traditional xenon flash Note that on many xenon flashes the lower the power setting the shorter the duration so included a medium power setting and the lowest power setting fastest mode You can clearly see that for that even for this air rifle pellet the xenon based flashes can not capture the image but the Airgap flash captures a very sharp image of the bullet in flight Canon 580EX 1 32 Power Canon 580EX 1 128 Power 1 42 Air Spark Flash The Airgap flash uses a flash tube filled with air gas ie the g
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