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Old 08-02-2014, 12:03   #16
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Re: How exact do electronics need 12 volts?

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Hi,

I bought a non-marine computer modem with a 120/220 volt power plug that converts it to 12 volts 1.67 amps. The actual modem input says 12 volts 1.66 amps.

I want to cut the power plug off and connect it into my 12 volt system which goes up to 14.4 volts day time.

Should the extra 2 volts be OK? Or will it blow the bloody thing to Kingdom Come?
There are usually two kinds of AC adapters, a simple transformer or a true regulated power supply. If you have the simple transformer one, the modem probably has its own regulation, and you'll be ok to connect directly to your 12v house power. If its a regulated 12v adapter, the modem might depend on that and have cheaper electronics itself, and then you need a dc-dc converter to clean up the power, or it might blow-up, or worse, work fine for weeks or months, and then fail.
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Old 08-02-2014, 12:22   #17
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Re: How exact do electronics need 12 volts?

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If its a regulated 12v adapter, the modem might depend on that and have cheaper electronics itself, and then you need a dc-dc converter to clean up the power, or it might blow-up, or worse, work fine for weeks or months, and then fail.
The adapter data sheet at PSAA20R-120
http://www.phihong.com/assets/pdf/PSAA20R.pdf

Says Line Regulation ±5% and Load Regulation ±5% so that means its Regulated?

Thank for your help
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Old 08-02-2014, 12:31   #18
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Re: How exact do electronics need 12 volts?

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The adapter data sheet at PSAA20R-120
http://www.phihong.com/assets/pdf/PSAA20R.pdf

Says Line Regulation ±5% and Load Regulation ±5% so that means its Regulated?

Thank for your help
Yep, that is switching regulated power supply, and not just a transformer, so chances are you could blow up the modem with the 12v house power.
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Old 08-02-2014, 12:41   #19
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Re: How exact do electronics need 12 volts?

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Yep, that is switching regulated power supply, and not just a transformer, so chances are you could blow up the modem with the 12v house power.
Thanks.

OK off to the shop Monday.
No Ebay, or Amazon in the Caribbean!


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Old 08-02-2014, 12:57   #20
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Re: How exact do electronics need 12 volts?

G'Day Mark, It will work BUT ensure you get the + right way as it is not always + to tip.

Regards
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Old 08-02-2014, 14:21   #21
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Good idea
These are the ones I've used..
http://www.amazon.com/Converter-3-5-...ref=pd_sim_e_6
Reliable so far, buy few, very handy.
Thanks for the link. It's worth it to have them always at the set voltage, even if my batteries are low my anchor light will be bright
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Old 08-02-2014, 15:01   #22
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Thanks.

OK off to the shop Monday.
No Ebay, or Amazon in the Caribbean!

Mark
I thought Amazon shipped worldwide
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Old 08-02-2014, 15:51   #23
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Re: How exact do electronics need 12 volts?

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Should the extra 2 volts be OK? Or will it blow the bloody thing to Kingdom Come?
In most cases it will be fine, but you don't know till you try it.

It is worth measuring the voltage of the supplied brick often it is over 12v which gives me more confidence. A simple solution is add one, or even a couple of diodes in series.this is very easy to do when you wire up the plug. Each one of these takes of about 0.6 v so one takes the battery voltage from say 12.3-14.4v to 11.7-13.8v which is usually better.
Make sure it is disconected for an equalisation cycle.

Anything for automotive use is usually designed to run off 13.8v (even if it says 12v) so has a little more leeway.
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Old 08-02-2014, 20:21   #24
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Re: How exact do electronics need 12 volts?

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I thought Amazon shipped worldwide
Like Gandhi said about democracy, overnight deliveries would be a good idea
Unfortunately what a next day delivery in much of the world actually ends up like is trying to guess which particular shack operating as an office your parcel might end up sitting on a shelf in and going to all of these every day for several weeks, also hoping you don't get stung for import tax because it's cloudy that day.
Next day deliveries are more an exercise in optimism than a system to transport goods.
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