are AC adapters interchangeable - Tilted Forum Project Discussion Community

Not Normal · 12-06-2004, 07:52 AM

Hi all, Question about a typical consumer electronic device in USA.

I've got a box full of AC adapters and no idea what devices they go with. If a given electronic device says "120v, 60Hz" by the AC jack, does that mean all I need is a AC adapter that says the same thing on it?

as god is my witness from now on I'm tagging all my power cables with the thing they supposed to go with...

thanks in advance

ScottKuma · 12-06-2004, 08:07 AM

Tagging the wall warts is a good idea.

If this is a transformer-style cord (the ones that you power small electronics with), the other thing you need to make sure of is "barrel polarity." You need to find out whether the barrel (the shiny outer part of the plug) is positive or negative.

There is usually a diagram on the device (and on the plug) that looks something like this:

+ -------C.-------- -

imagine that the period is a dot that's somewhat enclosed by the "C". This means that the barrel is positive and the "tip" is negative. Some universal adapters have tips that you can flip around on the cord to reverse this polarity.

Hope this helps!

ScottKuma · 12-06-2004, 08:14 AM

Here's a better example of the picture I was talking about:

Again, this represents a positive barrel polarity, negative tip polarity.

Not Normal · 12-06-2004, 08:34 AM

thanks for the quick response!

ScottKuma · 12-06-2004, 11:12 AM

You might also look at the amps that the device uses vs. the amps that the actual transformer provides.

If the transformer doesn't provide enough amperage (usually listed as mA - miliamps), the device may not work. For example, a wireless access point may need a lot of amperage while transmitting. Not providing enough amperage may make it LOOK like it's working, but may have serious effects during transmission. This will manifest itself as reduced range, spontaneous reboots during heavy traffic, etc.

Other devices may have problems if too MUCH current is provided. This can be a fire hazard. I had a problem with this once with old walkie talkies that I used another device's adapter for. The WTs got WAY too hot & eventually released the sacred blue smoke. (All electronic devices run on sacred blue smoke. If you release the smoke, the device will no longer work.)

Usually, the # of mAs on the device indicates the maximum draw the device will use. The # of mAs on the transformer indicates the maximum amount of power draw the transformer will provide.

a-j · 12-06-2004, 11:15 AM

You shouldn't really need to be concerned with the input specs (120v, 60Hz -- US specs, and I suppose elsewhere in the world) as almost every electronic device you own will have those specs, unless you have bought something from overseas, or have imported products. The output specs are what you need to be concerned about, and there are two other things you need to pay attention to besides the plug's polarity, which are just as important.

1. The output voltage needs to be the same. I suppose there are circumstances where you may be able to substitute a 13.6 v transformer for a 12v transformer, but this would vary on application, and since you are asking this questions, I think it is just safer to use the same voltage.

2. You need a tranforrmer with at least the same current rating, most likely you'll see something like 300mA (300 milliamps) on the transformer. This number must be greater than or equal to the current consumption by the device it is plugged into.

Electronics may list this information somewhere on the product or in the product manual. For example my work laptop has a sticker on the bottom that lists: 16v, 3.36A. The corresponding adapter has 16v, 4.5A on it.

a-j · 12-06-2004, 11:20 AM

Quote:

Originally Posted by ScottKuma

Other devices may have problems if too MUCH current is provided. This can be a fire hazard.

A transformer can't provide too much current. That doesn't even make sense. A device can draw too much current (depending on the supplied voltage and the resistance of the device), which is where the fire hazard comes in. That is why you have circuit breakers. If a device is drawing too much current, the transformer will heat up and probably fry one of the windings within it before it starts a fire. I did this with an old one I didn't need anymore using it as an electrolysis machine.

ScottKuma · 12-06-2004, 11:22 AM

Quote:

Originally Posted by a-j

A transformer can't provide too much current. That doesn't even make sense. A device can draw too much current (depending on the supplied voltage and the resistance of the device), which is where the fire hazard comes in.

I was editing my post as you posted yours, providing anecdotal evidence... Maybe my Walkie Talkies were bad, not given too much power. *shrug*

Redlemon · 12-06-2004, 11:51 AM

Thanks to everyone in this thread, including Not Normal for asking the question; I just uncovered an old electic piano keyboard without a cable in my attic, and I was wondering how to find a replacement.

goddfather40 · 12-08-2004, 07:06 PM

If the given electronic device says 120VAC, 60Hz, near the power input, then you don't need an AC adapter because the power doesn't need to be stepped-down, rectified, or regulated (or 'adapted' in laymen's terms) before it enters the device. Those devices probably only have a cord that plugs directly into the wall, and all the 'AC adapter' circuitry are internal to the device.

As others have said, an AC adapter provides one of the following:

1. stepped down AC voltage (i.e. 24 VAC)
2. DC voltage (usually something like 5, 9, 12 volts)

supafly · 12-11-2004, 01:49 AM

I have a comment on the "barrel polarity" post. When using AC the polarity switches 60 times a second (if frequency is 60Hz). It doesn'matter how you connect it, since there is no fixed polarity.
The current and voltage however need to match the device you are powering.

ScottKuma · 12-12-2004, 07:32 AM

NOT TRUE! Although you're correct that there's no fixed polarity, the device may be polarized, expecting the "hot" wire in the cord to be connected in a certain fashion. It may be this way so that the device can ensure that the fuse is the first thing that voltage reaches in the device, for example.

Remember that a 120V AC electrical outlet (In the United States, I don't know about other countries) usually has three wires. If your house has properly-wired polarized outlets, one of the two main prongs is larger than the other. The smaller of these two prongs is the "hot" wire...or the wire that brings electricity to the device. The larger of these is the "common", and the third wire is the "ground."

But regardless of that, most 120V AC powered devices use one of maybe three style cords (again, in the United States).

1) a PC-style, trapezoidal cord
2) a "playstation"-style, mini-plug that's rounded on both sides of the cord, and will fit into your device either way. Many coffee-makers use this kind of plug.
3) a "Dreamcast"-style, polarized mini-plug cord that's rounded on one side of the cord and square on the other side of the cord. This kind of plug will only fit a certain way into your device. This will ensure that the device is receiving voltage on the proper wire.

flat5 · 12-19-2004, 11:09 AM

A little knowledge is a dangerous thing.

"NOT TRUE! Although you're correct that there's no fixed polarity, the device may be polarized, expecting the "hot" wire in the cord to be connected in a certain fashion. It may be this way so that the device can ensure that the fuse is the first thing that voltage reaches in the device, for example."

This has nothing to do with the output of the adapter - which is the part that connects to the load/thing you want to power.

Except for the ground, plug polarity has not been too important since AC/DC radios :-)
If there is input isolation (like a transformer) you're ok.
As far as who gets to the fuse first - how do you guarantee that if the source is AC anf its going to a transformer (not a diode)?

ScottKuma · 12-20-2004, 07:45 PM

While I don't mind being corrected, your first comment was fairly uncalled-for.

Plug polarity is there for safety - especially in lamps, where there is a safety hazard if the barrel of the bulb holder is "hot". Granted, this is not a device where you have a transformer...but...

flat5 · 12-22-2004, 05:54 PM

Sorry if I made you feel bad. I see how you can take it personally.
A Little knowledge is dangerous in electricty.

"especially in lamps, where there is a safety hazard if the barrel of the bulb holder is "hot".

True. However you are supposed to unplug the lamp first :-)
If you mean ceiling fixtures, that could be a problem.

I have worked in an electronic lab that had ground faults.
It was possible to hook up test equipment from different benches
that would cause problems.

When I was a kid I used to work on electronic stuff, without shoes, in the garage
(cement floor) in the summer. I quickly learned to ground equipment with a wire to a steel pipe driven into the earth.

Again, I'm sorry. I was trying to be cute and ironical.

12-06-2004, 07:52 AM	#1 (permalink)
Not Normal Psycho Location: NY, USA	are AC adapters interchangeable Hi all, Question about a typical consumer electronic device in USA. I've got a box full of AC adapters and no idea what devices they go with. If a given electronic device says "120v, 60Hz" by the AC jack, does that mean all I need is a AC adapter that says the same thing on it? as god is my witness from now on I'm tagging all my power cables with the thing they supposed to go with... thanks in advance

12-06-2004, 11:12 AM	#5 (permalink)
ScottKuma Insane Location: Maineville, OH	You might also look at the amps that the device uses vs. the amps that the actual transformer provides. If the transformer doesn't provide enough amperage (usually listed as mA - miliamps), the device may not work. For example, a wireless access point may need a lot of amperage while transmitting. Not providing enough amperage may make it LOOK like it's working, but may have serious effects during transmission. This will manifest itself as reduced range, spontaneous reboots during heavy traffic, etc. Other devices may have problems if too MUCH current is provided. This can be a fire hazard. I had a problem with this once with old walkie talkies that I used another device's adapter for. The WTs got WAY too hot & eventually released the sacred blue smoke. (All electronic devices run on sacred blue smoke. If you release the smoke, the device will no longer work.) Usually, the # of mAs on the device indicates the maximum draw the device will use. The # of mAs on the transformer indicates the maximum amount of power draw the transformer will provide. Last edited by ScottKuma; 12-06-2004 at 11:20 AM..

12-06-2004, 11:51 AM	#9 (permalink)
Redlemon Devoted Donor Location: New England	Thanks to everyone in this thread, including Not Normal for asking the question; I just uncovered an old electic piano keyboard without a cable in my attic, and I was wondering how to find a replacement. __________________ I can't read your signature. Sorry.

12-08-2004, 07:06 PM	#10 (permalink)
goddfather40 Llama Location: Cali-for-nye-a	If the given electronic device says 120VAC, 60Hz, near the power input, then you don't need an AC adapter because the power doesn't need to be stepped-down, rectified, or regulated (or 'adapted' in laymen's terms) before it enters the device. Those devices probably only have a cord that plugs directly into the wall, and all the 'AC adapter' circuitry are internal to the device. As others have said, an AC adapter provides one of the following: 1. stepped down AC voltage (i.e. 24 VAC) 2. DC voltage (usually something like 5, 9, 12 volts) __________________ My name is goddfather40 and I approved this message. I got ho's and I got bitches, In C++ I branch with switches -MC Plus+

12-11-2004, 01:49 AM	#11 (permalink)
supafly Psycho Location: Rotterdam	I have a comment on the "barrel polarity" post. When using AC the polarity switches 60 times a second (if frequency is 60Hz). It doesn'matter how you connect it, since there is no fixed polarity. The current and voltage however need to match the device you are powering. __________________ Thumbs up

12-06-2004, 08:07 AM	#2 (permalink)
ScottKuma Insane Location: Maineville, OH	Tagging the wall warts is a good idea. If this is a transformer-style cord (the ones that you power small electronics with), the other thing you need to make sure of is "barrel polarity." You need to find out whether the barrel (the shiny outer part of the plug) is positive or negative. There is usually a diagram on the device (and on the plug) that looks something like this: + -------C.-------- - imagine that the period is a dot that's somewhat enclosed by the "C". This means that the barrel is positive and the "tip" is negative. Some universal adapters have tips that you can flip around on the cord to reverse this polarity. Hope this helps!

12-06-2004, 08:14 AM	#3 (permalink)
ScottKuma Insane Location: Maineville, OH	Here's a better example of the picture I was talking about: Again, this represents a positive barrel polarity, negative tip polarity.

12-06-2004, 08:34 AM	#4 (permalink)
Not Normal Psycho Location: NY, USA	thanks for the quick response!

12-06-2004, 11:15 AM	#6 (permalink)
a-j Tilted	You shouldn't really need to be concerned with the input specs (120v, 60Hz -- US specs, and I suppose elsewhere in the world) as almost every electronic device you own will have those specs, unless you have bought something from overseas, or have imported products. The output specs are what you need to be concerned about, and there are two other things you need to pay attention to besides the plug's polarity, which are just as important. 1. The output voltage needs to be the same. I suppose there are circumstances where you may be able to substitute a 13.6 v transformer for a 12v transformer, but this would vary on application, and since you are asking this questions, I think it is just safer to use the same voltage. 2. You need a tranforrmer with at least the same current rating, most likely you'll see something like 300mA (300 milliamps) on the transformer. This number must be greater than or equal to the current consumption by the device it is plugged into. Electronics may list this information somewhere on the product or in the product manual. For example my work laptop has a sticker on the bottom that lists: 16v, 3.36A. The corresponding adapter has 16v, 4.5A on it.

12-12-2004, 07:32 AM	#12 (permalink)
ScottKuma Insane Location: Maineville, OH	NOT TRUE! Although you're correct that there's no fixed polarity, the device may be polarized, expecting the "hot" wire in the cord to be connected in a certain fashion. It may be this way so that the device can ensure that the fuse is the first thing that voltage reaches in the device, for example. Remember that a 120V AC electrical outlet (In the United States, I don't know about other countries) usually has three wires. If your house has properly-wired polarized outlets, one of the two main prongs is larger than the other. The smaller of these two prongs is the "hot" wire...or the wire that brings electricity to the device. The larger of these is the "common", and the third wire is the "ground." But regardless of that, most 120V AC powered devices use one of maybe three style cords (again, in the United States). 1) a PC-style, trapezoidal cord 2) a "playstation"-style, mini-plug that's rounded on both sides of the cord, and will fit into your device either way. Many coffee-makers use this kind of plug. 3) a "Dreamcast"-style, polarized mini-plug cord that's rounded on one side of the cord and square on the other side of the cord. This kind of plug will only fit a certain way into your device. This will ensure that the device is receiving voltage on the proper wire.

12-19-2004, 11:09 AM	#13 (permalink)
flat5 Very Insignificant Pawn Location: Amsterdam, NL	A little knowledge is a dangerous thing. "NOT TRUE! Although you're correct that there's no fixed polarity, the device may be polarized, expecting the "hot" wire in the cord to be connected in a certain fashion. It may be this way so that the device can ensure that the fuse is the first thing that voltage reaches in the device, for example." This has nothing to do with the output of the adapter - which is the part that connects to the load/thing you want to power. Except for the ground, plug polarity has not been too important since AC/DC radios :-) If there is input isolation (like a transformer) you're ok. As far as who gets to the fuse first - how do you guarantee that if the source is AC anf its going to a transformer (not a diode)? Last edited by flat5; 12-19-2004 at 11:11 AM..

12-20-2004, 07:45 PM	#14 (permalink)
ScottKuma Insane Location: Maineville, OH	While I don't mind being corrected, your first comment was fairly uncalled-for. Plug polarity is there for safety - especially in lamps, where there is a safety hazard if the barrel of the bulb holder is "hot". Granted, this is not a device where you have a transformer...but...

12-22-2004, 05:54 PM	#15 (permalink)
flat5 Very Insignificant Pawn Location: Amsterdam, NL	Sorry if I made you feel bad. I see how you can take it personally. A Little knowledge is dangerous in electricty. "especially in lamps, where there is a safety hazard if the barrel of the bulb holder is "hot". True. However you are supposed to unplug the lamp first :-) If you mean ceiling fixtures, that could be a problem. I have worked in an electronic lab that had ground faults. It was possible to hook up test equipment from different benches that would cause problems. When I was a kid I used to work on electronic stuff, without shoes, in the garage (cement floor) in the summer. I quickly learned to ground equipment with a wire to a steel pipe driven into the earth. Again, I'm sorry. I was trying to be cute and ironical.