Combined charger and trigger cable for Sony mirrorless cameras like A6400

I often capture time lapse image sequences and do astrophotography. In both applications, a trigger cable and a proper means of powering the camera are essential. Keep in mind, that a fully charged battery usually lasts for no more than 3 hours.
At the moment, the only way to power a Sony mirrorless camera for a whole night or several hours is a dummy battery attached to a power supply (be it a mains power supply or a 7.2V battery driven sollution). With the release of the new models recently, like the A7III or A6400, the camera may also be powered through USB charger during image acquisition. (It may still be possible, that the battery drains, but far far less.)

This is really good news, as a USB power bank will provide the juice to run a whole night or even longer! But there arises one new problem: The external trigger remotes use the same USB port as it is used for charging.
This is possible, as Sony has created the so called Multiport some time back for use with their video cameras. The Multiport is an extended Micro-USB port with a second row of contacts. These contacts provide access to some control as well as audio and video output.

I did some research and came across Multiport connectors with solder pads for all 15 pins. See the pinout in the images at the end of the post.

Sony Multiport Adapter

With such connectors I was able to tailor a dual cable adapter, to charge and trigger the camera at the same time! I took a USB cable with male type A connector and a headphone extender cable with male 3.5mm plug. I chose both cables around 1m in length. This should be long enough in most use cases, but not too long to reduce charging performance.

Combined charger and trigger cable for Sony mirrorless cameras


The 3.5mm plug fits some of my trigger devices. All the others have 2.5mm plugs, for which I have adapter calbes in use. Most computer timer remotes with interchangeable camera plug sold, have a 2.5mm female audio jack. See attached image for the typical pinout.

Soldering the two cables to the tiny solder pads requires a steady hand and experience in soldering. The USB as well as the audio cables have quite thin wires (AWG26 to AWG28, which equals to 0.12 mm² to 0.08 mm²), except the USB power wires (AWG22 or AWG24 in quick charge cables, which equals to 0.32 mm² and 0.20 mm²). The wires are rather stiff. Therefore, aligning the wires to the solder pads may be tricky. It gets especially tricky, if the wires are exposed from the outer isolation for less than a centimeter.
Advice: Always check the finished cable for shorts and proper contact with a multimeter!

Soldered Multiport adapter with USB (bottom) and headphone (top) cables

To reduce wear, which may lead to wires breaking off the solder pads, I designed a connector housing / case. The housing holds the adapter as well as the cables in place. Furthermore, this is the only proper way to handle the connector upon pluggin to / unpluggin from the camera.
The connector case is 3D printed. I share the STL file on Thingiverse here:
https://www.thingiverse.com/thing:4279366

Multiport adapter case – 3D model in 2 parts

Disclaimer:
This is a guide put together as reference for me. If you follow this description, you will do so on your own risk. I may not be held responsible for any damage or injury caused!

3 Replies to “Combined charger and trigger cable for Sony mirrorless cameras like A6400”

  1. Hi MatP

    I found your website while trying to make a shutter release cable for my a6600 that can also charge it. Thanks for the very useful guide and diagrams.

    I have a question: have you attempted to use the 3.3V output from that port? Do you know anything about it?

    Thanks

    Frank

    You might be interested in something I’m working on: https://github.com/frank26080115/OpenMV-Astrophotography-Gear

    I would love to hear your feedback as you are also an engineer who does astrophotography.

    1. Hi Frank!

      I moved your comment from the About page to the “Combined charger and trigger cable…” page, as it refers to this page.

      You are very welcome!
      I did not yet have the need to harvest the 3.3V from the Multi-Port. So I have to dig in to the port specs. But as far as I remember, the 3.3V output is designed for low power applications.
      So without further reading, my guess would be: an active microphone oder microcontroller – yes. A GPS unit – probably. An external HDMI display – definitely no.

      MatP

      PS: love your 7E tag line 😉

    2. Hi Frank!

      I went through several documents. I could not find a hint on maximum allowed power consumption on 3.3V LANC_DC line (the 3.3V output on Sony Multiport Interface).
      The circuit diagrams and connectors of some LANC interfaces indicate, that the 3.3V line will not supply a lot of current. This is derived from:
      1) a standard USB connector is designed for maximum currents of 500mA. The LANC_DC pin uses similar wire widths.
      2) a 2.5mm stereo phone jack (TRS connector) is rated for maximum current of 500mA. The 2.5mm jack is one connector type used for LANC interfaces.
      3) the LANC voltage in video cameras is provided by a microchip without voltage regulator / voltage driver chips. All (or almost all) other voltages within the cameras (as I have found in service manual schematics) are controlled by the same chip, though they are backed by regulators.
      4) the majority of LANC interface hardware without their own power supply are simplistic switch devices for shutter, focus, zoom, … So they do not need a lot of hardware (apart from LANC communication)
      5) one of the LANC to RS232 interface chips (ELM Electronics ELM624 https://www.elmelectronics.com/ic/elm624/) has a maximum current draw of 2.4mA. So it is a low power interface. Combined with a micro controller, these switch devices may run at a few mA – most likely far less than 20mA.

      So, as long as I do not find the specifications of the LANC interface, I would rather use a separate power supply (battery, USB power bank, …) to drive any hardware drawing more than – probably – 50mA.

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