I recently bought this flash for my Canon 70D, a Yongnuo YN-14EX macro ring light.

Since it is equipped with a connector for external power supply...

... I want to build a power supply on my own.

My question: Which voltage needs to be provided to the different pins (in total 3 pins).

  • innovatronix.com/index.php/about-us/item/35-tronix-speedfire talks about 330Vdc, 800mA and 260W but I can't find any pin specs yet
    – dav1dsm1th
    Aug 13, 2015 at 9:23
  • photo.stackexchange.com/questions/49970/… is interesting
    – dav1dsm1th
    Aug 13, 2015 at 9:27
  • photography-on-the.net/forum/showthread.php?p=9438244 has (very questionable) pin diagram - but may provide clues for further googling
    – dav1dsm1th
    Aug 13, 2015 at 9:33
  • 1
    330V is common for speedlight flashes, a power converter steps up the battery voltage in the flash. To be certain, you could disassemble the flash and measure the operating voltage on the flash capacitor. Don't electrocute yourself. :) The flash will still require using its own AA batteries, to power its electronics and LCD. It won't operate without them. This is a tiny flash for macro, so my own notion is that any effort for power supply boost is pointless.
    – WayneF
    Aug 13, 2015 at 17:33
  • @WayneF: Thanks for the great and detailed comment! I actually want to run the flash on a stationary setup. Since LCD needs still the AA batteries, I realized, that an external power supply might not solve my problem... I'm therefore considering to replace the batteries with a 6V DC power supply.
    – user43016
    Aug 15, 2015 at 22:53

3 Answers 3


The voltage is stepped up to 300 volts and there is a control module that monitors the voltage. It would be pretty hard to build your own circuit.

There are some low cost versions of the CP-E4 battery pack on ebay for as little $25. I doubt you could build one cheaper.

$25 Ebay CP-E4 clones

pin arrangement

circuit board

enter image description here


I'd think an extra set or two of rechargeable NiMH AA batteries (Eneloops) should do it. For the small flash, it should easily do 200 or more flashes per set, then it only takes a second to swap out the batteries. One set could be recharging while the other set is in use.

  • I'll give it a try... :)
    – user43016
    Aug 16, 2015 at 12:37

Innovatronix (Tronix) has a new external power source called the SPEEDFIRE II that has both the high voltage output and dummy batteries. It will allow a full power Flash recycling time of about 0.2 seconds. at half power its virtually intantaneous.

Of course you must not fire your flash successively for more than 20 burst at the time because of the risk of overheating your flash tubes. :)

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