Future Improvements Roadmap

A project log for Edgerton, A High-Speed LED Flash

Affordable photography tool used to capture images of bullets with no apparent motion blur

Tyler GerritsenTyler Gerritsen 05/25/2019 at 03:470 Comments

Edgerton has been working well, but there is still room for improvement.  Some changes will require testing to implement properly, while others are going to be fairly straightforward to implement.  Here's a list of tests and improvements I intend to complete (ordered by priority).

  1. Lower Supply Voltage.  Using 8x AA batteries is very impractical, especially since the flash doesn't really need much power (LED's are more efficient than a xenon flashtube after all).  Additionally, the batteries are directly supplying the FET drivers, and as such the gate voltage is affected by the battery level.  Finally, the case size could be decreased by using fewer batteries.  I intend to accomplish this by adding a 12-volt boost converter and experimenting with a more efficient high-voltage boost converter.
  2. Better Voltage-Current-Luminous Power testing.  I've done some testing using a DSLR to measure light levels and the controller's on board ADC to calculate voltage current.  Better measurements can be taken with an oscilloscope and a light meter with an integrating sphere.  These measurements would be useful for selecting a drive voltage that maximizes lifespan and light output.
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  3. LED Series Resistors.  The flash works well without series resistors, but there is lots of ringing in the drive voltage.  I'm hoping to tame it with resistors, starting with some non-inductive resistors.  If there is any improvement, the expensive non-inductive resistors can be replaced with cheap 1/8W resistors to try decrease cost.
  4. MOSFET Gate Ferrite Beads & Clamping Diodes.  Ringing is also present in the gate lines.  I've ordered some ferrite beads to deal with the ringing.  If that fails, perhaps clamping diodes could work.  
  5. Flash Duration Testing.  Some commentors have expressed concern about the phosphor in the LED's.  The turn-off time may be affected by the phosphor, resulting in flash times longer than desired.  Hopefully tests with a photodiode and an oscilloscope can put those concerns to rest, but only testing will prove one way or the other.
  6. Firmware Improvements.  The firmware was proven to be robust, but new features could improve the value of the flash.  One commentor suggested making the flash able to trigger from a wire placed in from of a rifle's barrel (the flash would fire a set amount of time after the wire was broken).  Another asked if a modelling light mode was possible.  Finally, the flash could review the history on the EEPROM to self-diagnose health of the components.
  7. Removable Beam Focusing Device.  The diffused light from the flash is ideal in some cases (such as backlighting a diffuser panel) but in many situations a focused beam would be desirable.  A detachable array of lenses or reflectors - or perhaps a single fresnel lens - could allow the user to adjust the light for the situation.
  8. Alternative Batteries.  One commentor suggested using 18650 or 26650 batteries.  A modified version of the case could accept these batteries for users who happen to prefer LiPo batteries.
  9. Mini-Size Versions.  The current 12-LED model has plenty of power and I could see some users preferring a smaller, more affordable flash.  A 6-LED model would cost only a little more than 1/2 the price.