AC Adapter Question

From:	Ken (SHIELDSIT)	9 Oct 2014 09:04
To:	ALL	1 of 40

41232.1
If I have two devices that need 12v DC, can I power them with a single adapter or does each device need it's own? I'm not real great with electricity and I'd rather not kill myself or my equipment! Thank you my foreign friends! ------------------------------------------------------------------------ If you don't like donut, then leave it alone. Nobody force you to eat it.

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From:	JonCooper	9 Oct 2014 10:02
To:	Ken (SHIELDSIT)	2 of 40

41232.2 In reply to 41232.1
I'd say each gets their own, it would be more about the possibility of overloading the adaptor due to doubling the expected current drawn Jon

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From:	ANT_THOMAS	9 Oct 2014 10:11
To:	Ken (SHIELDSIT)	3 of 40

41232.3 In reply to 41232.1
As Jon said, should work as long as the adapter can cope with the current requirements. ┌─────┐ │ │ │ ┌─┐ │ │ │ │ │ │ └─┘ │ │ │ │ ┌─┐ │ │ │ │ │ │ │ │ │ └─┘ └─┘

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From:	koswix	9 Oct 2014 11:04
To:	Ken (SHIELDSIT)	4 of 40

41232.4 In reply to 41232.1

Depends on the current load. If the adapter an supply enough current (add up the current needed for both devices and see if it's less than the adapter can putnout).

Also connect them in parallel to avoid any voltage drop issues.


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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	Serg (NUKKLEAR)	13 Oct 2014 19:54
To:	koswix	5 of 40

41232.5 In reply to 41232.4
Kos! What?? If the adapter is 12V output AND can supply the sum of the current requirements, then he MUST wire them in parallel, otherwise they most definitely won't get 12V each. If the adapter can output 24V and sufficient current he still can't wire them in series unless he knows that the impedance of both is equal. Plus other nasty stuff. Also, hope that neither device has any peculiar load characteristics or dodgy circuit which could contaminate the single supply. [...Insert Brain Here...]

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From:	koswix	13 Oct 2014 20:54
To:	Serg (NUKKLEAR)	6 of 40

41232.6 In reply to 41232.5

Yes I know. That's why I said to wire them in parallel.


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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	fixrman	16 Oct 2014 19:21
To:	Ken (SHIELDSIT)	7 of 40

41232.7 In reply to 41232.1

I wish you'd have asked this before I threw some away.

All AC-DC adapters are not alike. You need to match the output voltage/amperage of the transformer to the desired input requirements of the device you want to power.

For instance, you may see that the adapter you want to use is a 12V unit, but it provides 9.8V continuous and 450mA output; the device you want to power may need 11.8V continuous but only need 380mA current. Also another nasty trick they can pull is that the power plug (gazinta the device) might be oriented incorrectly for what you want to use. I have found center positive or negative; that could be a problem. I have swapped the wires before if everthing else matched.

Let me know what you need because the ones I have are still here. Trash goes out tonight though. ;-)

Did you ever see such a messed up situation in your whole life, son?

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From:	koswix	16 Oct 2014 20:32
To:	fixrman	8 of 40

41232.8 In reply to 41232.7

Given his current condition perhaps he should be more worried about the back emf.


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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	Dan (HERMAND)	16 Oct 2014 20:41
To:	fixrman	9 of 40

41232.9 In reply to 41232.7
The voltage needs to be identical (or very close if you're feeling brave) but the max current output on the adapter only needs to meet or exceed the requirement for the device. I.e. if you have a 12v device needing 500mA a 12v 1A adapter will be fine. A 14v 500ma will not. I wouldn't be brave at all with modern electronics, but you used to be able to get away with it on some simpler devices. I'd almost forgotten polarity. Apart from laptops which are their own special beast, I'm not sure I own anything with a good old fashioned transformer. Everything is either USB standardised or IEC to the appliance. Dan Herman

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From:	koswix	16 Oct 2014 21:50
To:	Dan (HERMAND)	10 of 40

41232.10 In reply to 41232.9
I'd guess (and it is a guess) that voltage is less of an issue now. Or maybe the same level of issue. (within reason) With microcontrollers in everything these days the design is going to incorporate voltage regulators to provide either the 5v or 3.3v required for the logic side of things, so they shouldn't be affected. The rest of the circuit is probably no more or less voltage sensitive than older stuff. If you supply 14v instead of 12v I'd guess that everything would run fine (albeit a bit hotter). I'm not about to test it on anything I value, though :D ▪ ┌────┐ ┌────┐ │ │ │ │ ▪ │ └────┘ │ │ ──┐ ┌── │ ▪ ┌──────┤ ▪ ▪ │ ┌┘ │ │ ▪ ┌─┤ └──┐ │ │ ┌──┘ │ │ │ ││ ││ │ ┌─┐ │ │ └─┼┤ └┴─┴───┘ │ │ │ ─┘│ │ │ │ ┌──────┐ └┬──────────┘ │ │ │ │ │ │ │ │ └───┘ └───┘ If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	fixrman	16 Oct 2014 22:15
To:	koswix	11 of 40

41232.11 In reply to 41232.8

Yeah, maybe he should wrap the damn cord around his waist and stick the busines end in his mouth...

...said the bishop.

He could do well also to put about 7 strands of Christmas lights on as well. :-D

Current condition... love it! (dance)

Did you ever see such a messed up situation in your whole life, son?

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From:	fixrman	16 Oct 2014 22:17
To:	Dan (HERMAND)	12 of 40

41232.12 In reply to 41232.9

I'd not want to put anything but a dman close match myself; 500mA more current could damage some things, not knowing how well that wall wart is made.

Quote:

*I wouldn't be brave at all with modern electronics, but you used to be able to get away with it on some simpler devices.

If you said that, you said a lot there.

Quote:

I'd almost forgotten polarity.

You'd think it would be standard, but it isn't.

Did you ever see such a messed up situation in your whole life, son?

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From:	fixrman	16 Oct 2014 22:21
To:	koswix	13 of 40

41232.13 In reply to 41232.10

Quote:

that voltage is less of an issue now

The Chinese crap we get now? 8-O

Quote:

if you supply 14v instead of 12v I'd guess that everything would run fine (albeit a bit hotter).

You also might pop some cheap capacitors and electrolytics.

Quote:

I'm not about to test it on anything I value, though

Exceedingly prudent, my good man.

Did you ever see such a messed up situation in your whole life, son?

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From:	Dan (HERMAND)	16 Oct 2014 22:59
To:	fixrman	14 of 40

41232.14 In reply to 41232.12
But a current rating is simply a maximum output - current is drawn, not pushed, else your 60w lightbulb wouldn't last many minutes on a 1200w (average) circuit! Dan Herman

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From:	koswix	17 Oct 2014 00:05
To:	fixrman	15 of 40

41232.15 In reply to 41232.13

What Dan said - your power supplies are constant voltage, not constant current. The current drawn will be whatever is needed by the device.

Generally if you try and draw too much for an extended period the supply will die.


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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	koswix	17 Oct 2014 00:09
To:	fixrman	16 of 40

41232.16 In reply to 41232.13
>>You also might pop some cheap capacitors and electrolytics. Possibly, but 2 volts extra shouldnt dshouldn't do much. I'd wager that most components (even I'm cheap dodgy stuff) will be over specified because it's cheaper to go for the mass made stuff that's readily available than it is to get something that exactly matches your requirements. If 14v would kill it, I'd wager it's got a fairly limited life on 12v anyway. I should probably stress again that I'm just guessing here. I'm no electromagician. ▪ ┌────┐ ┌────┐ │ │ │ │ ▪ │ └────┘ │ │ ──┐ ┌── │ ▪ ┌──────┤ ▪ ▪ │ ┌┘ │ │ ▪ ┌─┤ └──┐ │ │ ┌──┘ │ │ │ ││ ││ │ ┌─┐ │ │ └─┼┤ └┴─┴───┘ │ │ │ ─┘│ │ │ │ ┌──────┐ └┬──────────┘ │ │ │ │ │ │ │ │ └───┘ └───┘ If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	fixrman	17 Oct 2014 02:55
To:	Dan (HERMAND)	17 of 40

41232.17 In reply to 41232.14

If I have an electronic unit that I like, why would I take a chance that the adapter is crap and smokes it? You can with yours, I'll just use the right one thanks.

Did you ever see such a messed up situation in your whole life, son?

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From:	fixrman	17 Oct 2014 02:58
To:	koswix	18 of 40

41232.18 In reply to 41232.16

Quote:

Possibly, but 2 volts extra shouldnt dshouldn't do much. I'd wager that most components (even I'm cheap dodgy stuff) will be over specified because it's cheaper to go for the mass made stuff that's readily available than it is to get something that exactly matches your requirements.

Tell that to the speaker amp I just repaired. Quote:

If 14v would kill it, I'd wager it's got a fairly limited life on 12v anyway.

Or maybe it is old and just can't handle it any more. Surely you've replaced a motherboard at least once for failed caps?

Did you ever see such a messed up situation in your whole life, son?

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From:	koswix	17 Oct 2014 07:00
To:	fixrman	19 of 40

41232.19 In reply to 41232.18

>>Surely you've replaced a motherboard at least once for failed caps

Nope, I missed that bandwagon. That debacle was due to badly made electrolytic capacitors, I think.


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┌─┤       └──┐  │  │  ┌──┘                      
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  │   │      │   │                              
  │   │      │   │                              
  └───┘      └───┘

If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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From:	fixrman	17 Oct 2014 12:15
To:	koswix	20 of 40

41232.20 In reply to 41232.19

Yes, that is true. Bad or poorly made power supplies could accelarate the popcorn effect.

Did you ever see such a messed up situation in your whole life, son?

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