Power inverters?

Ray

Couple of things to keep in mind with an inverter.

1) They can be electrically noisy. That is the way they create the AC power by chopping can be unsuitable for some electronics. My engineering experience shows them to be best suited for resistive/inductive loads. Things like lights, heaters, motors, etc. They also can emit a grotesque amount of EMI.

1a) Things with switching power supplies (small power supplies that sort of un-invert AC power) don't thrive well on this kind of power. These tend to be small electronics like laptops.

1b) Of course that is with low end inverters, if you want to use an inverter, look for one that references "sine wave" in the descriptive literature.(e.g. 2) Car battery is OK, motor on or off is up to you, Of course the battery will last longer if you keep charging it.

3) Inverter/Generator: The inverter will be smaller, the Generator will normally provide cleaner power. I don't know what your demands are so balancing performance is not possible. The generator also requires some sort of fuel.

Size will be the determining factor, If you choose cost, you will live to regret it, even though your video equipment may not....

If all of your equipment is portable, and you don't mind a little tinkering consider a battery/solar arrangement. (ref:

Hope this helps

Ray,

Power inverters will work, but bear in mind there is a fair amount of loss in doing the inversion. What I'd recommend is using a 12VDC TV/VCR (there are PLENTY of them out there), and try and get a receiver that will work off the 12V, as well. If you can't, then just use the inverter to power the receiver, to the 12V TV/VCR combo.

I'd recommend that you use a separate battery, as having it drain your car battery is a real concern. Those power-block units for jump starting batteries are pretty cheap, use one of those.

But (here's a good one to try), you may want to just by one of those UPS systems in a power strip that are sold for 30-40 dollars. That's a built-in battery with power inverter all rolled into one.

David Erbas-White

RayDunak>I'm trying to get set up for recording live video from an onboard video system,

If your going to go with an invertor, go for the best you can afford shy away from the cheap 150w versions as they tend to brown out as soon as you turn your tv on the sudden draw from the invertor causes the invertor to cut out.

I have to admit over here in the UK the people who tend to fly them most video have moved towards minidv camcorders or standard camcorders with an analogue input you run your 2.4 or 1.3ghz reciver from a small 12v dry cell and then run your camcorder from it's internal battery and use that to record the in flight footage. Works really well.

hope this helps

Damian

1. For powering electronics, I would suggest an inverter that provides an actual "sine wave" output. They are less efficient than a "chopped" and filtered inverter, but generate less electrical noise.
2. Bottom line: Is your video more important than getting home? (Not that its "unsafe" for the battery, rather, its starting your car after a long day of taping after accidentally leaving something turned on.)
3. Battery "amp-hour" ratings are usually based upon a 10 or 20 hour discharge time, ie, a 100 amp-hour rated battery is designed to provide

10 amps of current for 10 hours, or 5 amps of current for 20 hours. The power provided to a load is the product of current times voltage. Using the 10 hour discharge rate, a 12 volt battery providing 10 amps of current will support (10 A x 12 V =) 120 watts of load for 10 hours. Amp-hour ratings are like total impulse; you can take more current over a shorter time (20 amps x 5 hours = 100 amp-hours), or less current over a longer time (2 amps over 50 hours). Add up all the power requirements of your load (video stuff AND inverter) in watts and divide that by your battery voltage. It will give you the current drain on your battery and an idea how long the battery will last. Note: inverters are less than 100% efficient. That means it can require over 240 watts of input power from the battery to support 120 watts of video equipment if the inverter is 50% efficient. Check the power conversion efficiency rating of the inverter. Car batteries are designed to provide high current for short times. I use "deep cycle" marine/RV batteries for long term, lower current needs. If you can run your equipment on DC, you might want to skip an inverter altogether and just provide DC from the battery to all the equipment. No conversion losses to deal with.

1. Small generators have notoriously bad frequency control under load. Check the AC frequency input specs on your video equipment power supplies and make sure the generator AC freq output specs can meet them at load. However, a generator can be used to charge your batteries for those long, solo trips into the desert. :)

Also, for video, some home equipment may derive it's timing signals and set synchronous motor speeds, etc, from the AC line frequency; 60 Hz home power is very precise and stable. A field setup may not be as precise. Portable video equipment will not have this concern.

Hope this helps.

I've a gerry rigged car entertainment system which has saved the lives of 2 children. Using a standard $88 Wal-Mart Christmas special TV, a $50 VCR, $100 DVD player, and $30 Target clearance 300W power inverter (not to mention video games), I managed to get to PlasterCity without any undue violence. The startup draw of the TV would blow the fuse with the car running (worked fine when testing at home), so I had to be creative with fuses at a truckstop. The second trip I upgraded to a $120 5" LCD game cube monitor which draws a heck of a lot less current and occupies much less space. If you're going to be near the vehicle, the cheapest way to go. You don't have to worry about the battery, because you can have the car running (and sit in the AC). It also gives you shade to actually see the screen. Under an RV shade, on the north side no less, we were barely able to see a

27" TV they had setup at PB. I've watched motor certs at RainbowValley and with the laptop on the table under an easy up, they still had to throw a sheet over the screen and viewer. I believe it was that same day they were using a powerbrick which was a tiny generator. That would be the other way to go if your concern is more of using out of the house components without concern for power draw. But then you have to deal with gas and such.

I've one of those battery boosters, but haven't sat down to figure out how long it would actually last. If you're going that route, you would want to be very careful in your selection of components so you would get the max run time. Another idea would be a camcorder with input jacks. I haven't looked to see if any are made that way, but with the LCD screens it would be exactly the thing to use. Then you just need a small battery for the receiver (keeping in mind the sunshine issue).

Joel. phx

Taping would only be for a few minutes at a time, a few times a day at most.

Anyone know where I can get a decent TV/VCR combo that runs on 12v?

Maybe an RV store? Definently Bestbuy. Electronics->TVs->combo units->toshiba second page says ac/dc

Interesting thread on combo units.

The screen I bought is here (3rd down): on 12V and has simple inputs. I'm not fond of combo units because when the vcr goes you're left with only the tv anyway.

Joel. phx

Run it until your car won't start, then don't run it that long next time.

You got some interesting replies Ray.

I have run a VCR at a Launch off a 400W el-cheapo inverter, turning on the TV set only to check signal then shutting it off.

I suspect you are trying to do this on the cheap otherwise you would drop $400 on a camcorder with inputs.

If you have a laptop with USB2.0 jacks you can also get a video capture device.

I found that buying a 12V VCR that actually records is a bit pricy. Most are play only units.

True sinewave inverters will cost you more than buying a Camcorder so thats not an option.

If your only gonna run it for 15min at a whack you should be fine running off the cigarette lighter, but you might find that a bit restrictive. Maybe a seperate Gell cell is in order.

Get a $40 400W inverter and that will run your VCR just fine. It's the TV you have to worry about, maybe a $40 B/W cheapie from the drug store will do.

Good luck RDH8

Not an answer, but:

Which Video system did you get? 2.4Ghz? Does it have sound? Video quality? Range?

I've been looking for a decent one for almost a year now, and can't find one that I really like.

'Bout the best I could come up with was settling for an onboard camera and a later download. :(

How about something like this to bridge to your camera?

Stephen

Virtually ANY truck stop.

Ray: I would look into a usb video capture ..

has one... I'm sure there are usb2 ones...

You just plug the booster vision ground device into this usb video capture and use the enclosed software....

cheap and efficient...

and it all can run off a laptop with batteries..

shockie B)

Except LapTops suck in the sun.

Televisions aren't any better. Maybe a small tent could be utilized for sunlight and dust protection.

If you are considering a frame grabber, keep a couple of things in mind

1 - You need a lighting fast input - USB2 or consider 1294 (Firewire)

2 - If you save money on the frame grabber, be ready to pay for it in RAM on the PC., as buffering is critical and maximum memory is going to be required for best performance.

3 - While there are some good low end editing tools, consider something like Adobe Premiere - You will be happy in the long run.

Televisions are even worse... power sucking. Agreed... Tent for sunlight and dust protection.