Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

Started May 21, 2012 | Discussions thread
OP fabianbono Regular Member • Posts: 190
Re: wait, attach/power RF603 transmitter directly to flash

Dear Russell, how far we are going!!! it's amazing how a brainstorm like this can provide these results.

First of all I like to mention something, that is the base of my project.
My C3 is my family camera, so it is used by me or my wife also.

But she only uses on iAuto mode (that I must set before turn it off!!) and if need some case, use the flash.

Also sometimes I don't want to travel with a full bag of stuff, just the camera on his small bag hung from my shoulder.

Then, I need to have available the original flash too, just in case I use the C3 as Point and Shot.

And last, also I like to use the C3 mounted on a bracket, with the Yongnuo 560II flash at side, just connected by PC cable, without using Wireless triggers.

Basically, I don't want to loose any feature on the camera or in the flash.

Then, some comments based on your very interesting post.

RussellInCincinnati wrote:

Fabianbono, a further idea. How about using attaching a $20 dollar......

It is perfect idea for many people, but as I mention before, not for me. I want it all!!!

  1. The NPShsa NexProShop hot shoe adapter costs $80 dollars, ....


  1. There are many folks who would be very happy with modifying a $40 dollar Sony Nex....

More true.

  1. Yongnuo RF-603 transceivers only cost around $20 dollars.

Yes, I pay US$34 for a couple.

  1. The RF-603 has an on-off switch that could serve the same function as the Sony flash hinge-on-off switch.

  2. RF-603 can probably run fine off of a tiny bit of 5 volt POWER.

I think just use 3V inside from two AAA, is enough for current CMOS technology.
But agree that can be powered on that way.

  1. Pin 7 on the 14-pin proprietary Nex flash connector is 5 volt POWER.

I think yes, I didn't measure it when open mine.

  1. RF-603 itself comes with a hot shoe on top, and a pc sync cord output on its side. Plus it of course serves as a cordless radio trigger anyway.

Here's how we'd do it:


  1. Discard flash tube, the light output device. This "flash" is going to be just a radio transmitter now, it will never emit any light again.

Here I suggest to add some resistor to simulate the bulb, and discharge the capacitor to complete the circuit functioning.
We don't know the chip inside flash what kind of controls make on the circuit.

  1. Replace main, big Nex flash capacitor with a tiny one of same voltage rating . "Big" (percentage wise) weight savings here. Now the modified "flash" will never drain any power to speak of, nor will it take any time to "recycle".



  1. A final power lead goes from the output side of the RF603 on-off switch, to just beyond the now-disconnected hinge switch in the flash, to become the main "flash" power as well.

We need to investigate, but need to care on how much current use the RF603, in order to save the camera battery, that will serve all the stuff!!

May be because we remove the flash (bulb+capacitor), that battery saving is the same to power the RF603.
But better to confirm.

  1. inside the now-empty battery compartment of the RF603, put all resistors, transistors etc ......

  2. Glue 40-odd-gram RF603 directly to top of casing of modified Sony flash. Too bad we can't easily remove the bottom hot shoe from the RF-603 (or maybe we can, haven't analyzed this, it's not important in any case. Pun intended.).

Warning!!, be careful where you glue the RF603, since you need to continue accessing the RF-603 battery compartment to modify the small DIP Switch to change the Channels!!!
If not will be a mess to do it.

Result is a Sony Nex flash, lightened without flash tube or big internal capactor, permanently set into the compact "down position", with a Yongnuo RF603 permanently glued atop it. The RF603 providing a standard PC sync hot shoe atop it, a standard PC sync cord output on its side, and the thing is putting out a radio remote flash trigger as well that will be "automagically" picked up by other $20 dollar unmodified RF603 transceivers. Whole thing neatly powered by the Nex main battery.

Again, here I don't totally agree on the idea to set permanent the Flash On mode to brighten the LCD screen, since you also ALWAYS will block some ranges on Aperture and Shutter speed on your camera. (Hell yes, the Sony firmware do that...)
This give you less control on the exposure in my point of view.

Since the RF603's are only $20 dollars, and heck you were going to pay $10 dollars for a little dead hot shoe adapter, this isn't a bad mod even if you don't use the RF603 as a radio remote flash trigger.

Totally agree with your idea.
Cheap solution, and with more functions that other ones.
Just need a little of DIY practice, a magnifying glass and a soldering iron.

I will continue working on this when I receive my purchased items, this is around 3 weeks.
In the meantime, just continue researching!!

See you!

 fabianbono's gear list:fabianbono's gear list
Sony Alpha NEX-C3 Nikon D5200 Nikon AF-S DX Nikkor 18-105mm F3.5-5.6G ED VR Nikon AF-S DX Nikkor 35mm F1.8G Sony E 18-55mm F3.5-5.6 OSS +8 more
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