Why does this DC transformer have three output wires?
Why does this DC transformer have three output wires?
(OP)
Hi!
I'm making electronics for the film industry, and I'm working on making cables to power camera equipment.
I've made a lot of cables, all of which I'm terminating with 4 pin XLR jacks. If you aren't familiar with those, no need to look them up, because they aren't the problem.
The problem is, I'm on my last cable that I need to modify, and it's an AC/DC adapter from the 70s. It converts 120v to 20v to run the camera. I want to be able to run the camera off of the 12v battery pack, so I got a 12v to 20v transformer for the job.
I need to connect this transformer to the camera, and this can only be done by splicing into the proprietary cable coming out of the camera. It's got a red, black, and white wire in this cable, and it's supposed to be DC.
I don't want to ruin the camera, so I don't want to experiment to see what works.
Anyone know??
thanks!
Josh
I'm making electronics for the film industry, and I'm working on making cables to power camera equipment.
I've made a lot of cables, all of which I'm terminating with 4 pin XLR jacks. If you aren't familiar with those, no need to look them up, because they aren't the problem.
The problem is, I'm on my last cable that I need to modify, and it's an AC/DC adapter from the 70s. It converts 120v to 20v to run the camera. I want to be able to run the camera off of the 12v battery pack, so I got a 12v to 20v transformer for the job.
I need to connect this transformer to the camera, and this can only be done by splicing into the proprietary cable coming out of the camera. It's got a red, black, and white wire in this cable, and it's supposed to be DC.
I don't want to ruin the camera, so I don't want to experiment to see what works.
Anyone know??
thanks!
Josh






RE: Why does this DC transformer have three output wires?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Why does this DC transformer have three output wires?
I did find this post: http://www.eng-tips.com/viewthread.cfm?qid=89491&page=7
It says:
Positive of 3-wire d.c. RED
Middle wire of 3-wire d.c. BLACK
Negative of 3-wire d.c. BLUE
This doesn't help so much because I have red, black, and white. Also, middle wire isn't much a of a description.
Let me know what you think.
thanks!
Josh
RE: Why does this DC transformer have three output wires?
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Sometimes I only open my mouth to swap feet...
RE: Why does this DC transformer have three output wires?
I'm converting the same cord to have the ability to run off of a battery pack.
thanks,
josh
RE: Why does this DC transformer have three output wires?
One wire might be a ground wire, but it should be green.
If a dummy battery must be inserted in order to run from AC, there might be some kind of detection scheme to assure that there isn't a real battery installed.
If the internal battery consists of a number of cells or a battery with three terminals, more than one DC voltage level might be involved.
RE: Why does this DC transformer have three output wires?
I'm sure the camera treats the dummy battery the same as it would a real battery, it just ensures it's the proper voltage.
The internal batteries total up to 20v, which is what the DV transformers supply....
i dono....
josh
RE: Why does this DC transformer have three output wires?
RE: Why does this DC transformer have three output wires?
So the question is...
If this common cord is involved, and I am converting it to splice in with a modern two wire DC transformer...what do I do with the common cable?
Will it work without it?
I also need to find out which is which (red, white, and black)
thanks!
Josh
RE: Why does this DC transformer have three output wires?
RE: Why does this DC transformer have three output wires?
You may be able to tell by carefully looking at the battery holders where the three wires are connected.
I wouldn't connect anything new without measuring to see what you have. If you need +10V and -10V, you will need two external 12V batteries and two 12V to 10V converters.
RE: Why does this DC transformer have three output wires?
I opened up the dummy battery and I was able to see the backside of the connections. Turns out I should have been posting in a camera forum instead of an electronics forum because the extra cable (the white one) seems to be a sync cable (it goes to another small jack on the dummy battery so the sound recorder can tap in and keep the audio in sync with the video).
thanks for all your input!
-Josh
RE: Why does this DC transformer have three output wires?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com