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Old October 23rd, 2006, 06:12 PM   #1
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Wireless Projection

Has anyone tried a wireless projection setup?

I was thinking about using this portable power supply to power a laptop and projector:
http://www.amazon.com/Xantrex-852-20...712947?ie=UTF8

And using a second one of those power units to power this sound system:
http://www.bhphotovideo.com/bnh/cont...=246346&is=REG

And then use this wireless audio system to send the audio from the laptop to the sound system:
http://www.bhphotovideo.com/bnh/cont...goryNavigation

In theory, there wouldn't be any wires for anyone to trip on or tape down and you wouldn't have to use the DJ for the audio. However, I'm not sure how reliable it is, so if anyone has any experience with wireless projection, I'd be very grateful for your advice.

Here's a link to other things you might need in that setup.
http://www.kaboodle.com/monstercrayons/projection.html
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Old October 23rd, 2006, 09:31 PM   #2
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In theory it would work great. I don't think you would need to use the first power supply for the laptop because those can run on their own for at least 40 minutes if they have a charge the night before. And you shouldn't need a second unit because the sound system can normally be located close to a power source, outdoor venues being a question mark.

I think that for the wireless you should step it up to the 500 if your looking at the azdens. Something like this: http://www.bhphotovideo.com/bnh/cont...goryNavigation

That would serve as a solid on camera unit for ceremony duty when it's needed.

As long as the video isn't wireless I think it would work great with the portable power units. The venue coordinators would probably appreciate the setup more than the clients.

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Old October 24th, 2006, 02:07 AM   #3
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Thanks for the link...
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Old October 24th, 2006, 04:17 AM   #4
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The gist of what follows is an explanation of why that power unit may not be strong enough to reliably run a projector due to the size of the battery and the high draw of a projector:

That power unit is a 28 amp/hour sealed lead acid battery. I'm assuming it is a gel-cell model like similar devices. A projector draws a large amount of power. The bulb alone is probably 200Watts or more and there is a fan and some circuitry to run. Assuming a projector is about 250Watts, this is approaching half of the total battery energy. What many people don't know is that lead-acid batteries provide less total power if they are drained quickly. Usually, they are rated at their 20-hour load. That means that you get 28 amp/hours (336Watts for one hour equivalent) only if you draw about 15Watts at a time! At the rate a projector would suck power, you may only get 20 minutes of run time. It could be more, but you will risk permanently damaging the battery if you run it down all the way. Also, if you run it down all the way at a high draw, you can cause bubbles in the gel. There is a type of lead-acid that can take more punishment, but I doubt this has an Absorbant Glass Mat cell as they are not yet common in small devices.

I use 55 amp/hour sealed AGM lead-acid batteries to power location fluorescent lights and can run about 200Watts for a few hours. Of course, 200Watts from a 55 amp/hour battery is less stressful than 250Watts from a 28amp/hour model. The AGM technology is also less prone to failure from rapid discharge and recharge.
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Old October 24th, 2006, 02:59 PM   #5
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Thanks for your post Marcus. Do you have a link to where one can purchase the 55 amp/hour battery you use?
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Old October 25th, 2006, 08:01 PM   #6
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I have never attempted any kind of wireless video communication, but I know it has been a reliable way to send information for close to 20 years. Just what it takes in terms of equipment is the issue I can not answer.

However, I can after 23 years of dealing with wireless audio systems, offer the following opinions:

1. The safest way to transmit any kind of signal is via a balanced hard wire connection.

2. Wireless means "without wires". That statement may appear as having a firm grasp upon the obivous, but the truth is that any kind of wireless transmission is vulnerable to infection from other kinds of wireless transmissions. This"infection" is almost never intentional, but it could (and often does) impact the quality of your data

3. The resolution requires a bit of homework, but is rather straight forward.

I'm not sure what happened, but this post was somehow submitted before I was ready to do so. I believe that is called "dex-lexia". Please procede to the next post with my name attached.
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Old October 25th, 2006, 08:16 PM   #7
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I have never attempted any kind of wireless video communication, but I know it has been a reliable way to send information for close to 20 years. Just what it takes in terms of equipment is the issue I can not answer.

However, I can after 23 years of dealing with wireless audio systems, offer the following opinions:

1. The safest way to transmit any kind of signal is via a balanced hard wire connection.

2. Wireless means "without wires". That statement may appear as having a firm grasp upon the obivous, but the truth is that any kind of wireless transmission is vulnerable to infection from other kinds of wireless transmissions. This"infection" is almost never intentional, but it could (and often does) impact the quality of your data

3. The resolution requires a bit of homework, but is rather straight forward.
First, know the broadcast frequencies your system can use.
Second, discover what more powerful broad frequencies are in use in the local area you plan to be in that could overlap the frequencies you had selected to use. Any reputable manufacturer of wireless broadcast equipment will provide this information in their technical support pages online.
Lastly, look towards the "unexpected culprits", like mobile phones (if within a meter or two of your receiving station), the start-up phase of heating and air-conditioning electric motors in small buildings, and even the positioning of antennas relative to our constant passive compaion, the electric light bulb.

Postscript: Most of the signal contamination we receive came from something we thought we could take for granted. It is such a part of us we forget what it really represents.

Most of the time my admonitions should make no sense, because they very likely will not make themselves known. However...
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