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Arctic_Eddie
Post Laureate
Reged: 12/30/07
Loc: St. Petersburg, FL
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Camera Power Supply
#4937563 - 11/27/11 03:37 PM Attachment (32 downloads)
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Camera Power Supply
There was a discussion recently in this forum about powering a camera from the mount's 12V battery. Several regulator ideas were put forward but one in particular was quite promising. The regulator is a switcher with 95% efficiency and only about 1"x2". Even more surprising is the price of $2.20US with free shipping from Hong Kong. Midnight Dan and myself both ordered several of these units.
This project is intended specifically for a Panasonic FZ50 camera which uses a 7.4V lithium cell. The regulator is set for 8.4V which is the peak value for a fully charged battery. The project can be applied to any camera provided you have the appropriate plug on the camera side and the voltage is set to the correct value.
The first photo shows all of the components for an AC and a 12V supply. The AC part comes from an eBay seller and was purchased for two reasons. First, there are occasions where the scope battery may not be convenient but a wall socket is accessible. Second, you need the appropriate connection to the camera which may not be available as a separate item. The commercial supply solves both problems. In the photo, the AC adapter is at the bottom with it's line cord input on the left and the 8.4V output on the right. Note that the camera plug has been cut off and replaced with a Molex 062 2-pin female socket. The 8.4V supply is at the top with it's 12V input on the left and includes a 3A inline fuse holder. The 8.4V output cable is on the right and terminates in a Molex 062 2-pin female socket. The short pigtail in the middle is the remains of the AC output cable and is fitted with a Molex 062 2-pin male plug on one end and a type "C" coaxial plug on the other.
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Arctic_Eddie
Post Laureate
Reged: 12/30/07
Loc: St. Petersburg, FL
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Re: Camera Power Supply
[Re: Arctic_Eddie]
#4937577 - 11/27/11 03:43 PM Attachment (23 downloads)
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The second photo shows the internals of the 8.4V supply. The box is a die-cast aluminum container which is common for electronic projects where strength and shielding are desired. The 12V input cable is on the left and passes through a rubber grommet installed in the wall of the box. The PC board is mounted on two Stakon eye connectors split open and bent at 90°. They are bolted to the side wall of the box with #6 hardware. The blue object near the upper-right corner of the PC board is a ten turn trim pot and used to set the output voltage.
This apparatus works quite well and was tested by running the camera for an hour with no heating of any of the components. As mentioned earlier, you can use this idea on any camera needing less than the scope battery voltage and with the appropriate connection device.
Link to switching regulator. Price dropped another $0.05.
http://www.ebay.com/itm/260858526297
Edited by Arctic_Eddie (11/27/11 03:51 PM)
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Gene7
scholastic sledgehammer
Reged: 06/10/10
Loc: Mid Ohio, USA
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Re: Camera Power Supply
[Re: Arctic_Eddie]
#4937873 - 11/27/11 06:16 PM
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Or for control of DC voltage and/or current just use the old faithful LM317 3 terminal IC with a resistor or two. Obtain any voltage you want. Google it out, there are a dozen or so examples on the web. Gene
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Arctic_Eddie
Post Laureate
Reged: 12/30/07
Loc: St. Petersburg, FL
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Re: Camera Power Supply
[Re: Gene7]
#4937898 - 11/27/11 06:31 PM
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Very true for the LM317 but it's a linear regulator and wastes energy as heat. The switcher is much more efficient at any load current and is adjustable, like the LM317, for any voltage less than the supply voltage up to about 40V. The load current can go up to about 2A where the LM317 might be less.
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Arctic_Eddie
Post Laureate
Reged: 12/30/07
Loc: St. Petersburg, FL
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Re: Camera Power Supply
[Re: Arctic_Eddie]
#4937958 - 11/27/11 06:58 PM
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I have just been in communication with Midnight Dan and discover that he has developed another useful application for the switcher power supply board. He will soon publish his project on this forum. Since these switchers are now down to $2.15US we may see more applications useful to astronomers.
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