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Old 19-08-2013, 19:55   #16
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Re: Hard wiring a wireless router

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Originally Posted by smac999 View Post
I bet if you measure that 12v power supply it's up around 13-14v already.

I've hard wired lots of stuff like that. just make sure you get the wires correct as normally they are just both black.

That's what I was thinking too.

Usually the tip is positive, but not always.

If you are in the US, then Radio Shack will probably carry the plug that you need. They also have fuses & fuse holders.

If you want to play it super safe, they also carry voltage regulator IC chips in a TO-220 case for less than $5. #LM7512 or 7812 is the one that you want. It's just 3 pins, input, gnd & output. http://www.radioshack.com/product/in...lickid=prod_cs or NTE1970 -Integrated Circuit-Voltage Regulator 12V TO220 ISO : Voltage Regulators | RadioShack.com A full-geek data sheet can be found here - LM7512C datasheet - 12 Volt Regulator
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Old 19-08-2013, 20:04   #17
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Re: Hard wiring a wireless router

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Originally Posted by pbiJim View Post
If you want to play it super safe, they also carry voltage regulator IC chips in a TO-220 package for less than $5. #LM7512 or 7812 is the one that you want. It's just 3 pins, input, gnd & output. RadioShack 12V Fixed-Voltage Regulator 7812 : Voltage Regulators | RadioShack.com or NTE1970 -Integrated Circuit-Voltage Regulator 12V TO220 ISO : Voltage Regulators | RadioShack.com A full-geek data sheet can be found here - LM7512C datasheet - 12 Volt Regulator
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Old 19-08-2013, 20:40   #18
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Re: Hard wiring a wireless router

The OP asked for a 12v supply. The LM78xx won't deliver that on normal boat 12v, it requires 14.6v to deliver a constant 12v (if I read the data sheet correctly).

Besides, IC regulators are terribly in-efficient, they reduce voltage by burning off the excess to heat in proportion to load.
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Old 19-08-2013, 21:04   #19
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Re: Hard wiring a wireless router

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The OP asked for a 12v supply. The LM78xx won't deliver that on normal boat 12v, it requires 14.6v to deliver a constant 12v (if I read the data sheet correctly).

Besides, IC regulators are terribly in-efficient, they reduce voltage by burning off the excess to heat in proportion to load.
Ah yes, you are right, I missed that.

I've always used the 5V version so it's never been a problem. Naughty me for doing a boy-look at that datasheet! Should have thought about it, you always get SOME voltage drop over any kind of diode.

However, I have never noticed significant heat production from these ICs and I use them to drive some pretty heavy loads with the solar tracking systems, shunting relays for the tracking motors etc. I will load one up tonight and see how it behaves, just out of curiosity.
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Old 19-08-2013, 21:47   #20
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Re: Hard wiring a wireless router

I have had a cheap Netgear WGR614NAR hardwired to my dc system for a few years. No issues yet. I would echo the poster above who said if it is a cheap router, just hook it up and see.
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Old 19-08-2013, 22:08   #21
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Re: Hard wiring a wireless router

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The OP asked for a 12v supply. The LM78xx won't deliver that on normal boat 12v, it requires 14.6v to deliver a constant 12v (if I read the data sheet correctly).

Besides, IC regulators are terribly in-efficient, they reduce voltage by burning off the excess to heat in proportion to load.
I said that it could be used if the person wanted to be super safe. It's not a perfect option, but it will prevent over voltage & therefore prevent risk of damage to the downstream device.

Probably nothing is actually needed for over-voltage protection. Hooking up to the house bank through a small fuse is all that is probably necessary.

Another option would be to add a zener diode after the fuse. That would cause the fuse to trip in the event of an over voltage condition.
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Old 19-08-2013, 23:08   #22
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Re: Hard wiring a wireless router



This is a switching DC-DC, so pretty efficient,
and is adjustable for 12v or 9v or 6v or 3v..


$4.00

LM2596 Step Down Adjustable 1.5-37V DC/DC Converter | MPJA.COM
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Old 19-08-2013, 23:44   #23
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Re: Hard wiring a wireless router

Have a 12V TPLink 3G WiFi Router hard wired direct to a spare switch/breaker on my main panel for over 18 months. No probs.

Dave
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Old 20-08-2013, 06:23   #24
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Re: Hard wiring a wireless router

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This is a switching DC-DC, so pretty efficient,
and is adjustable for 12v or 9v or 6v or 3v..

$4.00

LM2596 Step Down Adjustable 1.5-37V DC/DC Converter | MPJA.COM
That certainly is a good value for what it is, but I think that it's going to have the same limitation that the LM7512 will have. I think that it will necessarily put out less voltage than it takes in. It is listed as a step down device. I don't see a kick up device anywhere in the schematic.
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Old 20-08-2013, 06:46   #25
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Re: Hard wiring a wireless router

You have been given some advice.
In most cases it will be fine on the boat supply and its probably cheap enough to risk. As someone suggested measuring the voltage of the AC brick that came with it will give you some idea. If it poorly regulated (say measuring 14v without any load) than its more likely it will OK with a direct connection to the boat system.

As others have said simple 12v stabilising circuits are not great because they produce a few volts voltage drop. There are more sophisticated circuits that boost the voltage first, but these circuits are more complex and less efficient.

The simplest solution is to 1 or 2 diodes (in series) with the power supply. These will reduce the voltage by about 0.5v each, moving the boat voltage into a range that is unlikely to cause problems.
Low voltage is unlikely to cause damage (but may cause drop outs) so try 2 diodes first. If it stops working with low house voltage change to one diode. Very simple, not foolproof, but low risk.
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Old 20-08-2013, 07:18   #26
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Re: Hard wiring a wireless router

Similar to this: Amazon.com : BESTEK 90w adapter universal laptop charger dc adapter socket car cigarette lighter charger hp laptop adapter acer notebook charger compaq laptop adapter gateway notebook charger hp ac adapter Compaq charger dell laptop adapter toshiba n

Cut off the cigarette plug end and wire into the house DC.

The link was just a quick search and shows a 15V-24V version. You can find them in 5V-12V also. You can also find vendors selling them for $6-8.

Mark
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