Topic: AC power in the field

[balou2]

Hey folks,
A couple basic questions I'm hoping can be answered.  I'm looking for a good portable AC solution in the field.  A couple years back I tried something call the Vector Pocket Generator.  Awesome idea, terrible reliability.  I need something more reliable.  Question is, what is the best way to go?

- Is there a way to use an Ecocharge and an inverter to provide AC?

Any help would be great!...and I'm not handy enough to build my own at this point.

Mike

[peeeper]

I've posted this before so anyone that's herd this, bare with me....

I suggest not to go the DC/AC inverter route.  The process of changing DC to AC creates high amounts of RF noise which could cause other electronic devices, such as your recording equipment, not to perform as desired.  Whether or not this is noticeable in the recording, the potential is there.

There I said it.

In addition, ultimately all electronic devices use DC voltage.  So to take a DC voltage from a battery and invert it into AC just to have it nverted back to DC (in the device i.e. AC adpater for a laptop) is a waste of energy and you'll need more battery power.  When you should just supply the device with the DC voltage it requires for it to operate from the get go.

[Patrick]

Bump on this thread...can anyone else give some input to balou's question?

[peeeper]

- Is there a way to use an Ecocharge and an inverter to provide AC?

Ok fine..... 

Yes you can.  First you'll need to find the pin out to EcoCharge battery connector, meaning which pin is positve and which pin is negitave.   A cheap multi-meter can act as your tool.  Even though this is a DC circuit it really doesn't matter what the polarity is but it is good practice.  Grounding is not much of a concern; but if there is one, you might want to also note it.  Typically, the negative is also ground in a DC circuit but EcoCharge could be isolating it for some unknown reason.  I'm assuming that the EcoCharge battery you are attempting to use provides 12VDC, since most of the inverters I've seen require 12VDC to power the inverter.  Ok, so you've mapped out the pins and you are now ready to create the connection from the EcoCharge to the inverter.  I would cut off the car cigarette-lighter connector of the inverter (near the connector) and replace it with the opposite sex connector of the Ecochage battery.  Note that the center of a car cigarette-lighter connector is positive and the outside is negative so you might also want to mark the leads going into the cigarette-lighter connector.  If there was a ground on the EcoCharge battery connector, and you really want to use it and if the chassis of the inverter is metal, attach it to the chassis of the inverter.  The metal of the chassis should be ground.  This would probably require a bit of wire on your part.  24 AWG to 20 AWG would be sufficient.  Normally, the inverter should have mounting holes for you to mount the inverter in a car.  Here you can use hardware to fix a ground using Faston Crimps to the inverter.  Or if you don’t want to use a ground just terminate the ground pin to the negative pin of inverter inside of your new connector you’ll be adding.  Once you have the connections made, power the inverter up and you should have AC power at the outlet that you’ll be using to plug in an AC device.

Not knowing the power requirements of (1) the inverter (2) the devices you are planning on powering and (3) the battery rating of the EcoCharge.  I can not tell how long of a battery life you’ll have.  Although I do know this is a very inefficient way to power any device.

-Good Luck and I hope this helped…   

[balou2]

- Is there a way to use an Ecocharge and an inverter to provide AC?

Ok fine..... 

Yes you can.  First you'll need to find the pin out to EcoCharge battery connector, meaning which pin is positve and which pin is negitave.   A cheap multi-meter can act as your tool.  Even though this is a DC circuit it really doesn't matter what the polarity is but it is good practice.  Grounding is not much of a concern; but if there is one, you might want to also note it.  Typically, the negative is also ground in a DC circuit but EcoCharge could be isolating it for some unknown reason.  I'm assuming that the EcoCharge battery you are attempting to use provides 12VDC, since most of the inverters I've seen require 12VDC to power the inverter.  Ok, so you've mapped out the pins and you are now ready to create the connection from the EcoCharge to the inverter.  I would cut off the car cigarette-lighter connector of the inverter (near the connector) and replace it with the opposite sex connector of the Ecochage battery.  Note that the center of a car cigarette-lighter connector is positive and the outside is negative so you might also want to mark the leads going into the cigarette-lighter connector.  If there was a ground on the EcoCharge battery connector, and you really want to use it and if the chassis of the inverter is metal, attach it to the chassis of the inverter.  The metal of the chassis should be ground.  This would probably require a bit of wire on your part.  24 AWG to 20 AWG would be sufficient.  Normally, the inverter should have mounting holes for you to mount the inverter in a car.  Here you can use hardware to fix a ground using Faston Crimps to the inverter.  Or if you don’t want to use a ground just terminate the ground pin to the negative pin of inverter inside of your new connector you’ll be adding.  Once you have the connections made, power the inverter up and you should have AC power at the outlet that you’ll be using to plug in an AC device.

Not knowing the power requirements of (1) the inverter (2) the devices you are planning on powering and (3) the battery rating of the EcoCharge.  I can not tell how long of a battery life you’ll have.  Although I do know this is a very inefficient way to power any device.

-Good Luck and I hope this helped…   

+T peeper.  This is DEFINITELY too much issue for me.  I just keep hoping that somebody will answer back with a magical mystery AC cure so I can run my Rosetta too!

Thanks man.
MIke

[leegeddy]

Even though this is a DC circuit it really doesn't matter what the polarity is but it is good practice.  Grounding is not much of a concern; but if there is one, you might want to also note it.  Typically, the negative is also ground in a DC circuit but EcoCharge could be isolating it for some unknown reason.

peeper;
man 'o man, you should really re-read what you've wrote about dc's polarity. it DOES matter. 

marc

[jk labs]

Get a battery
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=23-275

and an DC-AC inverter
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=22-146

and your are go in no time.

The battery is also gone in no time. It packs 84 Wh and the Rosetta wants 45 Watts. But 7Ah should last an hour or so all things considered. This is enough to test the concept and benchmark how many batteries you need. Worst case you'll need four and a strong back. Otoh you get all the excercise you need free of charge. 
   
Cabling, polarity, fuses, shorts, cooling, carrying cases, acid, recharging etc you can address as you go. Ie   
a little EE knowledge is required within the assembly team.

There are a few issues here but the important thing is to test the concept and then refine per need.

[peeeper]

7Ah should last an hour or so all things considered

I'me sure this is even less concidering you not taking in to account the energy that is needed to power the inverter.

[Patrick]

+t's for the advice, despite most of it being a thumbs down on AC power!

So, is there a safe way to mod an AC powered unit to DC?

I guess one can dream, right? 

[leegeddy]

+t's for the advice, despite most of it being a thumbs down on AC power!

So, is there a safe way to mod an AC powered unit to DC?

I guess one can dream, right? 

in many cases, it's not too difficult. you just have to figure out what the source needs.

look for the AC in > transformer > rectifier circuit > DC out.

for example, the Sony RMR-D100 took a 110vac > step down transformer > 11vac > bridge rectifer > 9vdc. i simply removed/bypassed the transformer/rectification stage and supplied a 9vdc to the correct terminals. worked like a charm.

marc

[peeeper]

So, is there a safe way to mod an AC powered unit to DC?

Depends on what the device is.  In the past I’ve taken a few different types of equipment that had a built in power supply and only had an AC plug going into it and I bypassed the power supply.  For example, I was able to open the device up and while it was powered on take measurements of the DC voltage and the current coming out of the power supply circuit of the device.  Most AC devices have a power supply that changes the AC to DC, which then powers the actual device.  If you can figure out what the power requirements are for the device, past the power supply circuit, then you can bypass the built in power supply with another source for the DC voltage and current required.  In my applications that I've done, I was able to bypass the built in power supply in the way I described above.  Once I did this I was able to remove a heavy transformer which is a typical part of an AC to DC power supply.  It really reduced the over all weight of the device, since I knew I was going to power it using batteries instead of AC.  This was one of the reasons for me doing this.  On some devices the power supply circuit is a separate printed circuit board (PCB) with only two wires (one positive and one negative) jumping to the main PCB of the device.  If you can supply your own DC voltage then you can totally remove the power supply PCB with transformer from the device.

Now I really don’t recommend anyone opening up a device that uses AC while it is turned on.  If you don’t know what you are doing it can be deadly.  Also quite a few devices need several different DC voltages to power different aspects of the device, which complicates things but the principle is the same as I described above.  If you haven’t had any electrical or electronic training I would suggest not even trying unless you have someone that does or if you have detailed instructions and precautions for the actual device in question.

Current is a killer!      

[peeeper]

Even though this is a DC circuit it really doesn't matter what the polarity is but it is good practice.  Grounding is not much of a concern; but if there is one, you might want to also note it.  Typically, the negative is also ground in a DC circuit but EcoCharge could be isolating it for some unknown reason.

peeper;
man 'o man, you should really re-read what you've wrote about dc's polarity. it DOES matter.

Marc you are absolutely correct and thank you for checking me on it, I meant to speak about how an AC circuit the polarity rarely matters, not DC.

thank you   

[jk labs]

+t's for the advice, despite most of it being a thumbs down on AC power!

So, is there a safe way to mod an AC powered unit to DC?

I guess one can dream, right? 

Thumbs down? I don't agree. I did look at the RS parts and to me it looks like you can take the battery, clip on the color-coded power "alligators" and the inverter is alive and kicking. You'd have AC in less than it takes to decide which pair of socks to wear!

You do have to work a little to make it suitable for lugging around. And with 45 Watts draw at say 80% efficiency (I didn't look for specs for the inverter but 80% is doable today) you are drawing (45W/12V)*(1/0,8) Amps. I don't think you'll be far away from drawing 5 Amps. With safety margin you suck down a 7Ah battery per hour. A 12V 25 Ah SLA is needed for 4+ hours of recording. That's your real drawback.

Or is it?  Lets see where DC powering puts us.
You look at maybe (I'm just guessing) a 6V 10Ah for the 5 V sections and TWO 12 V 5Ah SLAs to run the analog stages if there are  + and - rails.  If the internal voltages are regulated to 12 or 15 Volts you need TWO banks each made up of 12 & 6 V 5 Ah SLA. 5 SLAs in total. This is no great saving in weight! An the logistics of making a carry case for 5 SLAs plus wiring them all up (as well as make arrangements for recharging) can get messy.

[Massive Dynamic]

+t's for the advice, despite most of it being a thumbs down on AC power!

So, is there a safe way to mod an AC powered unit to DC?

I guess one can dream, right? 

in many cases, it's not too difficult. you just have to figure out what the source needs.

look for the AC in > transformer > rectifier circuit > DC out.

for example, the Sony RMR-D100 took a 110vac > step down transformer > 11vac > bridge rectifer > 9vdc. i simply removed/bypassed the transformer/rectification stage and supplied a 9vdc to the correct terminals. worked like a charm.

marc

Has anyone ever peeked inside a Sony R-300 for possible DC operation?  Power consumption is listed at only 30 watts. If I could run my home deck at the handful of local shows I see each year, I'd sell my portable.

I know the Tascam DV-RA1000 DVD recorder owners are planning to use Exceltech inverters. Wonder how they'll fare?

[JackoRoses]

That is one nice inverter, did you find a good deal on it by chance?
Thanks for the test results very informational!