How do you convert 12V to 5V? - AVS Forum
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post #1 of 29 Old 12-16-2011, 09:17 PM - Thread Starter
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I need to power a Bluetooth wireless music receiver that is to be attached to a 12V car stereo on my boat. The purpose is to wireless stream audio from my iPad 2 to the boat stereo hardwired speakers.

The Bluetooth receiver comes equipped with an AC charger. The charger specs are
Input: 100 - 240V ~ 50 - 60Hz 65mA 6.5VA
Output: 5V = 350mA

As I don't have a handy AC power source, I'm obliged to use the boat's 12V power. I require a converter to go from 12V input to 5V output to power the Bluetooth receiver.

I'm a dummy with electricity so all help/advice is greatly appreciated.

Any ideas where I can buy one?
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post #2 of 29 Old 12-16-2011, 09:44 PM
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The best thing to do would be to pop into Canadian Tire and grab an inverter.
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post #3 of 29 Old 12-16-2011, 10:07 PM
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A common item really as these days plenty of people want to hook up their portables to the car.

Go to amazon.com and search for "5v car adapter" and find the type of plug u need, and that will give you at least 350mA output.


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post #4 of 29 Old 12-16-2011, 10:21 PM
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I had suggested inverter since he mentioned that it was on a boat. I don't know if he has a cig lighter plug, but the inverter would allow for anything that requires 120v to be plugged in.

Here's a good one which comes with a cig lighter plug cord or can be wired directly: http://www.canadiantire.ca/AST/brows....jsp?locale=en
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post #5 of 29 Old 12-17-2011, 07:31 PM - Thread Starter
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Quote:
Originally Posted by sebberry View Post

... grab an inverter.

Most of the small wattage output inverters require a 12V cigarette lighter connection to power the inverter. The layout would look like this:
12V wire -> cigarette lighter -> inverter -> AC charger -> Bluetooth receiver (that's 3 pieces of hardware between the 12V wiring & the Bluetooth receiver).
Because this stuff will not be accessible, it will have to be constantly turned on. Do you think there's an issue with this setup drawing a lot of current from the boat's batteries?
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post #6 of 29 Old 12-17-2011, 07:46 PM - Thread Starter
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Quote:
Originally Posted by MrBobb View Post

A common item really as these days plenty of people want to hook up their portables to the car.

That's where I got the idea of streaming my iPad.
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Go to amazon.com and search for "5v car adapter" and find the type of plug u need, and that will give you at least 350mA output.

Amazon returned 20,000+ hits. Too overwhelming! I don't know what to look for.
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post #7 of 29 Old 12-17-2011, 08:41 PM - Thread Starter
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Would this be a more elegant solution? Here's a recommendation I got from digikey.com for a 12V to 5V converter as per above: CUI's VYB10W-Q24-S5-T10 W, 5 V, 2 A, Single Output, Chassis Mount Dc-dc Converter.
http://products.cui.com/adtemplate_c...bcatky2=603795
LL
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post #8 of 29 Old 12-17-2011, 09:30 PM
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oh so u don't want a temporary cig-type connection, u want a permanent, mounted solution! Fine that box looks like it's spec'ed correctly.

As far as idle consumption, I went into the trouble of reading the spec sheet and it says nothing about idle power consumption so u will have to ask the vendor. If you are concerned, I know when hooking thing like this in a car, you can either hook it up to the ALWAYS ON POWER (no matter where the key is), and ACC ON (only powered when the key is in the ACC position).


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post #9 of 29 Old 12-18-2011, 01:55 PM
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The MotoMaster inverter I linked to can be wired directly to the electrical system.

You can either wire it direct to the battery (preferably with a fuse) or into the ACC or IGN circuits of the boat.

Although the one I linked to will work, you may want to consider something marine-rated if it is a permanent installation. I don't know how insurance works for boats but if there was ever a problem with it and there was a fire, etc... using non-marine rated components might be a problem.

You could talk to the guys down at West Marine and see what they suggest, but it will be considerably more expensive.
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post #10 of 29 Old 12-18-2011, 01:59 PM
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Quote:
Originally Posted by Kaal View Post

Would this be a more elegant solution? Here's a recommendation I got from digikey.com for a 12V to 5V converter as per above: CUI's VYB10W-Q24-S5-T10 W, 5 V, 2 A, Single Output, Chassis Mount Dc-dc Converter.
http://products.cui.com/adtemplate_c...bcatky2=603795

That would work too if all you need is a 5v connection.

With an inverter you could plug in various devices that run off a standard 120v household plug, but with the DC-DC converter you'd only be powering 5v devices. Fine if you're tucking it away somewhere and hard-wiring everything in.
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post #11 of 29 Old 12-19-2011, 05:47 AM
 
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An LM7805 is a common 5V linear regulator. $0.77 in single quantities.

http://search.digikey.com/scripts/Dk...lm7805&x=0&y=0
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post #12 of 29 Old 12-19-2011, 05:53 AM
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Sounds complicated for a wet environment. Any chance your car stereo can play CD's with MP3s on them? You could just burn a bunch of songs onto a disc and stick it in. I've been on some scubadiving liveaboards where that's all we did for the whole week.
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post #13 of 29 Old 12-19-2011, 08:26 PM - Thread Starter
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Quote:
Originally Posted by sebberry View Post

I don't know how insurance works for boats but if there was ever a problem with it and there was a fire, etc... using non-marine rated components might be a problem.

It's a non-issue. There are only a few things on a boat that are marinized. Everything else is also usually found in a home or RV. Even things that are not rated by recognized authorities like UL or CSA shouldn't be a problem. What is important is that an insured must declare to the insurer things that increase the risk.
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You could talk to the guys down at West Marine and see what they suggest, but it will be considerably more expensive.

The car stereo guys don't give it away either.
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post #14 of 29 Old 12-19-2011, 08:59 PM - Thread Starter
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Quote:
Originally Posted by chrpai View Post

Sounds complicated for a wet environment. Any chance your car stereo can play CD's with MP3s on them? You could just burn a bunch of songs onto a disc and stick it in. I've been on some scubadiving liveaboards where that's all we did for the whole week.

It's dry, just a little humid at times. An advantage of using the iPad is that I can go-on-line to access the web. Pardon the pun, but there's a boat-load of music on the web that I can play. Or listen to the radio when I'm miles from shore & no station reception. I'll use my 3G connection & pull it off the web.
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post #15 of 29 Old 12-19-2011, 09:32 PM - Thread Starter
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Quote:
Originally Posted by SAM64 View Post

An LM7805 is a common 5V linear regulator. $0.77 in single quantities.

That's why I love avsforum! A "common 5V linear regulator" to you folks is simple, but complete greek to me.
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post #16 of 29 Old 12-19-2011, 11:57 PM - Thread Starter
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Quote:
Originally Posted by sebberry View Post

That would work too if all you need is a 5v connection.

That's all I need.
Quote:


With an inverter you could plug in various devices that run off a standard 120v household plug, but with the DC-DC converter you'd only be powering 5v devices. Fine if you're tucking it away somewhere and hard-wiring everything in.

I'd be splicing into the stereo's power line and everything will be very difficult to access. I understand the various advantages of an inverter (I've got a 2800). I'd like to continue looking at the alternatives. It seems that the inverter requirement spec calls for the more expensive pure sine wave type.
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post #17 of 29 Old 12-20-2011, 12:40 PM
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Quote:
Originally Posted by Kaal View Post

That's why I love avsforum! A "common 5V linear regulator" to you folks is complete greek to me.

And it's not that simple either. You need to use a heat sink and add capacitors around the device as well.

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post #18 of 29 Old 12-20-2011, 08:31 PM - Thread Starter
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Quote:
Originally Posted by Glimmie View Post

And it's not that simple either. You need to use a heat sink and add capacitors around the device as well.

Not simple & very confusing too. Simple would be an over-capacity pure sine wave inverter, min cost about $100.
Confusing - Digikey 1st suggests a $37+ part; SAM64 finds a Digikey 77ยข part (Digikey agrees with SAM64 "As for the LM7805 that will also do the job.) and no suggestion from them for a heat sink or capacitor. I guess they aren't the best source for advice.

Please, can someone help spec this for me?
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post #19 of 29 Old 12-21-2011, 12:54 AM
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This is a simple thing. Am thinking of all the kids walking around with the iPod, phone chargers, they output 5V, about an amp or less, and either 120v input (220 available) or their cig lighter plug in the car.

Why are u having so much trouble?

I see a boat-minder, a dock handy man in your future.


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post #20 of 29 Old 12-21-2011, 04:36 AM
 
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I guess they aren't the best source for advice.

They're a parts supplier, not a school.

Quote:


Not simple & very confusing too.

It's a three terminal device and there are tons of application examples on the web.
At 350mA you probably won't need a heatsink, use a 10uF capacitor on the output to prevent oscillation.
...or use on e of the other solutions, my apologies for the advice.
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post #21 of 29 Old 12-22-2011, 11:53 AM
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An LM7805 is the simplest method and only requires 2 additional components; a 10 mfd electrolytic cap on the input and a 100 mfd cap on the output. All grounds are connected together and the entire setup can be housed in a small metal box where the box acts as the heat sink. Any beginning geek can assemble it with only a drill for the mounting hole of the LM7805 and a small soldering iron.

All parts are available at Radio Shack.

They also carry a line of 12v to various voltage adapters where only the output plug is selected to match and cell phone or other DC device.
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post #22 of 29 Old 12-23-2011, 07:35 PM - Thread Starter
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Quote:
Originally Posted by MrBobb View Post

I see a boat-minder, a dock handy man in your future.

You've got it partially correct - it's past, present & future! Victoria is the centre of some of the finest boat cruising areas in the world. My 38' power boat is my floating cottage that involves a good amount of my time. The details of electricity has always been voodoo to me. Thanks for your input.
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post #23 of 29 Old 12-23-2011, 08:29 PM - Thread Starter
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Quote:
Originally Posted by SAM64 View Post

They're a parts supplier, not a school.

True. But look at the amount of help from some of the manufacturers & suppliers. It's absolutely fantastic. This is from Monoprice (1 of the advertiser on the AVS Forum masthead: "...In regards to your inquiry, I'm sending this follow up email to see if you have any additional questions that I can help you with. Please let me know if there is anything else I may assist you with. Thank you for making Monoprice your preferred place to shop online.
If you have any other questions feel free to email us or you can also chat with our online Tech Support Team via our online Chat." And another from Vicor Corp: "Technical advice furnished by Vicor is provided as a free service, whose intent is to facilitate successful implementation of Vicor Products."
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post #24 of 29 Old 12-23-2011, 08:54 PM - Thread Starter
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Originally Posted by Gizmologist View Post

An LM7805 is the simplest method...

Great! Thanks so much.
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post #25 of 29 Old 12-24-2011, 06:49 AM
 
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Quote:


But look at the amount of help from some of the manufacturers & suppliers.

If you go to the website of the manufacturer(there are many of them)of a 78XX series of regulators you will find dozens of application examples on how to use their products.
Digikey is a parts supplier, they don't manufacture anything.
The easiest and most inexpensive solution to creating a 5V supply from 12VDC is to use a 7805 regulator. I posted that in an attempt to help you.
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post #26 of 29 Old 12-30-2011, 11:10 AM
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Radio Shack carries a system called I-Go that has 12 volt power connectors and then a coiled cable that can use any number of interchangeable adapters to connect to most any 5volt device. Just match the adapter connector and away you go. Fast and easy and quite reliable.
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post #27 of 29 Old 01-04-2012, 11:47 AM
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Quote:
Originally Posted by Kaal View Post

I need to power a Bluetooth wireless music receiver that is to be attached to a 12V car stereo on my boat. The purpose is to wireless stream audio from my iPad 2 to the boat stereo hardwired speakers.

The Bluetooth receiver comes equipped with an AC charger. The charger specs are
Input: 100 - 240V ~ 50 - 60Hz 65mA 6.5VA
Output: 5V = 350mA

As I don't have a handy AC power source, I'm obliged to use the boat's 12V power. I require a converter to go from 12V input to 5V output to power the Bluetooth receiver.

I'm a dummy with electricity so all help/advice is greatly appreciated.

Any ideas where I can buy one?

Many cell phones need 5V power. Any chance the plug in your set matches the power plug of a cell phone car charger?
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post #28 of 29 Old 03-01-2013, 06:19 AM
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Here is what I did.

I took a cheap usb car charger you buy on ebay. like the one you see bellow. Open it up and soilder the points I have marked. Then you can put the charger back together and heat shrink the bottom. Looks good and works great. Makes life, easy, cheap and quick. We own a party bus biz and constantly need 5v hook ups for cameras, iphones, etc etc. Was not willing to pay $30 bucks for some unit.








Let me know if this helps.
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post #29 of 29 Old 03-07-2013, 02:00 PM
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I had exactly the same challenge on my boat - to find a 5v dc power supply for various things. Many household chargers convert 120vac to 5vdc so it's handy to have 5vdc available for things like walki-talkies, usb hub, network hub, iThings, etc. I didn't want to use an inverter because they are famous for having a constant parasitic load on your battery even if there is no downstream load. They are really inefficient.

I found this device: Meanwell SD-15A-05. I bought it on eBay but don't see this model there now - but many similar ones. Here's one source I just found: http://www.powergatellc.com/mean-well-sd-15a-05-dc-dc-converter.html I don't know this vendor at all.

I put it on a switch so only have it on when I need it.

Good luck,

JR
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