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#1 Phil Rhodes

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Posted 15 November 2007 - 02:30 PM

Hi,

I'm in the process of putting together three identical sets of 2.4GHz video transmitters and receivers for video assist work, the sort of thing which would be used to get video tap material back from steadicam.

Each transmitter or receiver has a single six-pin series 7R Hirose connector for power, left and right audio and video and has been modified for wide range power input of 7 to 34 volts. I am planning to produce a variety of breakout and adapter cables to cover as many situations as possible but I thought I'd canvas the board's opinion on the small but critical topic of power connectors.

The most obvious thing to grab is a 4-pin XLR, which is the closest thing we have to a standard, but they're comparatively huge - as long as the transmitter is itself, and about a third as wide. I'll certainly make at least one set of cables with 4-pin XLR power, but I would prefer to find something smaller.

The next nearest thing that exists to a standard is the 4-pin Hirose, as used on both Steadicam (carrying power and video) and most video cameras (carrying power and sound). I believe the power pinout is identical in both cases. This seems to be a quasi-standard among sound recordists who frequently have power breakout boxes with 4-pin Hirose power, so I'll be producing cables to this standard as well.

24v power devices seem to commonly use 3-pin XLR connectors but I would consider it to be a fairly uncommon situation to want to power a tiny video transmitter from an enormous camera power brick. Beyond this, there's the domestic-style DC connectors which exist on the side of PAG plates, the Anton Bauer power takeoff connector which seems to be custom, plus whatever strange things various 35mm film cameras have by way of power outputs.

Any thoughts very much appreciated - I can't make up cables for every conceivable situation, it's a factorial problem, but I'd like to get the bases covered as completely as is reasonably possible.

Phil
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#2 Alessandro Machi

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Posted 15 November 2007 - 02:42 PM

I purchased a power supply off of eBay that had a faux 4 pin connector set up. it came out of the power supply with two rows of 3 across plastic encased receptacles with a plastic flange underneath that "locked" into the power supply. The other end of the cable was 4 pin XLR. Although at the end of the day, the actual connector coming out of the power supply was almost as large as an XLR connection port.

I don't know what to do with the 3 remaining ones that I have, they barely output 12 volts and the voltage drops lower depending how long the cable is and what the actual voltage is coming out of the wall. I had two 13.2 volt HMI ballasts go bad the same weekend I started using these power supplies so I stopped using them.

Be careful on your outputs, the 12 volt, 13 volt, and 14 volt set-ups might be considered interchangeable but if one goes below 12 volts it could be just a matter of time before their equipment suffers from "browning out" due to too low of a voltage.

You may want to consider having notched points on your variable power supply units to prevent accidentally underpowering your more expensive gear.
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#3 Phil Rhodes

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Posted 15 November 2007 - 03:47 PM

Hi,

I don't think there'll be too many problems with that - I've modified the transmitter-receiver pairs with switching power supplies which will regulate anything between 7 and 34 volts to the 5V they need, and if it drops below 7V, you've got a very knackered battery on your hands - and all that will happen is that the device will stop working.

It's more a question of what sort of power connectors are commonly being used.

Phil
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