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    #41
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    Eugenio: I wouldn't recommend asking someone to make up a special unit for you using the components I mentioned. Building electronic devices is fine if you are a hobbyist, but it is very time consuming and you will rarely up with a device as compact, economical or as neat looking as a manufactured device. For me to design and build a regulated supply for the GH2 would take several hours and cost three times as much as an off-the-shelf device (if available). I'd have to buy the components, breadboard the design to test it first, then solder them on a circuit board which I'd have to make, add leads, mount everything in a case, and provide external connections. I suggest in your case to stick with off-the-shelf components bought locally.

    For instance, if weight is not a problem, why not use a sealed lead-acid battery? Robust, reliable, lasts for years, cheap and readily available. As an example, here is a battery that would power a GH2 for a dozen hours or more and costs about $30 here in Australia: http://www.jaycar.com.au/productView.asp?ID=SB2486. Battery shops, motorcycle shops, all sorts of shops sell them. Another benefit, to charge it you could use a cheap 12-volt charger designed to charge car batteries.

    You'll need a good regulated DC-DC converter, of course, and that's the tricky part. Automotive shops may sell them. Probably sell the battery too. And a digital multimeter if you haven't got one. Take a 10-ohm, 10 Watt resistor with you and do this:

    1. Hook the regulator to the battery, the resistor to the regulator, and the meter to the resistor. Check the voltage across the resistor. If it is greater than 8.6 volts, buy battery, buy regulator.


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    #42
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    Quote Originally Posted by g.l View Post
    It's a good idea, but do we know that the body would accept an 'official' battery that puts out more than the official voltage? I think it's likely it will detect that as a dangerous situation (assuming a battery malfunction) and shut down.

    ... or (reading your post again), did you mean with a DC converter built-in?
    Yes, you are probably right. A higher voltage from an official battery might cause the camera to shut down. Or it might wreck the camera electronics. The modified DCC8 that I am suggesting would of necessity (see below) have a regulator built in so that it outputs 7.2 volts.

    I've been trying to think of a reason why Panasonic requires external supplies to be greater than 8.4 volts. The only one I have come up with is: for protection purposes. When running of the internal battery, there is virtually no possibility that an error can be made. The polarity is correct, the voltage cannot be too high. So the internal electronics can be powered straight from the battery. However, Pansonic may have decided that for external supplies, they had better build in some protection against wrong polarity and high voltage. They don't want cameras being returned because someone has applied reverse polarity, for example, and destroyed the internals. Such protection circuitry may require an overhead of a few volts. A possibility is that when an applied voltage of > 8.4 volts is detected, protection circuitry inside the GH2 is switched on, and that protection circuitry unavoidably causes a voltage drop of, say, 2 volts. i.e. for an external supply, maybe the GH2 isn't purposely cutting off at 8.4 volts, but it cuts off because the external 8.4 volts - 2 volts (assumed voltage drop in protection circuitry) falls below that required by the GH2.

    If that is the case, it may be absolutely necessary to use a 7.2 volt regulator inside a modified DCC8, to prevent voltages higher than 8.4 volts (known to be safe) being sent directly to the camera internals, and to protect against user error (external supply being of wrong polarity, or voltage too high).


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    #43
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    This is the battery:

    http://cgi.ebay.co.uk/ws/eBayISAPI.d... ht_6747wt_698

    This is the regulator:

    http://br.mouser.com/search/ProductD...5u0nVBmg%3D%3D

    This two intens in the hands of a good professional electronics, along with the instructions here (regulator output at 8.6 v 1.5 mah), I am well served?

    Thanks, I'm looking forward to starting construction.


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    #44
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    Quote Originally Posted by guyburns View Post
    Because the GH2 internally has a cutoff voltage that is probably around 6.6 volts, maybe even as low as 6.0 volts.
    I guess what raised my question is the fact that putting less than 8.4v to the camera results in it not working.

    Mark


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    #45
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    Quote Originally Posted by g.l View Post
    Similar simpler versions do exist on Ebay (everything included, just adjust a trimmer to set your output voltage). I have no idea how reliable they are, but they may be fine. They're called DC DC 'step-up' / 'boost' converters (smaller V in, higher V out), or 'step-down' / 'buck' (higher V in, smaller out). Make sure they handle your input V range (max & min charged state), and that you will input enough voltage for the desired output voltage (the step-downs typically need a bit more voltage going in than coming out).
    Virtually identical module with free shipping:
    http://cgi.ebay.com/LM2596-DC-DC-Ste...-/320570868469

    UK link:
    http://cgi.ebay.co.uk/LM2596-DC-DC-S...-/320570868469
    Last edited by chon; 04-19-2011 at 12:17 AM. Reason: switched the ebay links to a seller with better feedback


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    #46
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    How about this, a Li-ion battery with a 9V 8.5Ah output, comes with charger:
    http://cgi.ebay.com/5V-9V-12V-DC-Rec...-/160438173336

    I'm guessing the 5V and 9V outputs are regulated since they're not multiples of 3.6V.


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    #47
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    Quote Originally Posted by Eugenio View Post
    This is the battery:

    http://cgi.ebay.co.uk/ws/eBayISAPI.d... ht_6747wt_698

    This is the regulator:

    http://br.mouser.com/search/ProductD...5u0nVBmg%3D%3D

    This two intens in the hands of a good professional electronics, along with the instructions here (regulator output at 8.6 v 1.5 mah), I am well served?

    Thanks, I'm looking forward to starting construction.
    Regarding the battery: I think you will be disappointed. You get what you pay for. I doubt very much that a 12 volt, 6.8Ah Li-ion battery costing $30 (with charger) will retain its capacity after more than a few discharges. But it's only $30 so you haven't lost much.

    As for the DC-DC regulator, the Texas Instruments requires extra components and someone to set it up for you: tell them 8.6 volts. No other specification is required. You may be better off with the cheap regulators mentioned by Chon (post above). It appears to have an on-board voltage adjustment that you could do yourself.


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    #48
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    Quote Originally Posted by guyburns View Post
    Regarding the battery: I think you will be disappointed. You get what you pay for. I doubt very much that a 12 volt, 6.8Ah Li-ion battery costing $30 (with charger) will retain its capacity after more than a few discharges. But it's only $30 so you haven't lost much.

    As for the DC-DC regulator, the Texas Instruments requires extra components and someone to set it up for you: tell them 8.6 volts. No other specification is required. You may be better off with the cheap regulators mentioned by Chon (post above). It appears to have an on-board voltage adjustment that you could do yourself.
    Regarding the battery, thanks for the tip, I'll keep searching and buy a good reference.

    Regarding the voltage regulator, I have a professional who can configure it for me. I cherish the very security of GH2, and I want a good voltage regulator. In his opinion the voltage regulator PTN78000WAH is safer than the alternatives Chon?


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    #49
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    Quote Originally Posted by Eugenio View Post
    Regarding the battery, thanks for the tip, I'll keep searching and buy a good reference.

    Regarding the voltage regulator, I have a professional who can configure it for me. I cherish the very security of GH2, and I want a good voltage regulator. In his opinion the voltage regulator PTN78000WAH is safer than the alternatives Chon?
    Don't worry, the chip has both overcurrent limitation and overheating cut off. A bit overkill, but you could get a 5A regulator if you feel the need:
    http://cgi.ebay.com/LM338K-DC-AC-6V-...-/290547727625
    http://cgi.ebay.com/5-Amps-Voltage-R...-/130428364896


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    #50
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    Quote Originally Posted by chon View Post
    Don't worry, the chip has both overcurrent limitation and overheating cut off. A bit overkill, but you could get a 5A regulator if you feel the need:
    http://cgi.ebay.com/LM338K-DC-AC-6V-...-/290547727625
    http://cgi.ebay.com/5-Amps-Voltage-R...-/130428364896

    The AC GH2 has an output of 1.2 mah. in my view the regulator has to have at most 1.5 mah for security reasons.

    This thinking is wrong?


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