Ac-dc adapters in series (or parallel)

In summary: In either series or parallel powering, fuses would be another layer of protection.In summary, it is possible to connect multiple 220V to 5v, 2A ac to dc adapters to the same 2-phase input terminals, but it is not recommended as it can be unsafe and may cause damage to the adapters or the device being powered. It is better to use a single power supply with the correct voltage and amperage for the application. If multiple adapters must be used, they should be tested for compatibility and care should be taken to prevent back-driving in case of overload. It is also important to make sure that the output voltage is smooth and regulated, as some adapters may have unfiltered output.
  • #1
hackhard
183
15
multiple 220V to 5v, 2A ac to dc adapters connected to the same 2-phase input terminals
input voltage is 220v domestic supply.
is it safe to i join output in series to obtain 10v /15v/25v etc. ?
 
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  • #2
hackhard said:
multiple 220V to 5v, 2A ac to dc adapters connected to the same 2-phase input terminals
input voltage is 220v domestic supply.
is it safe to i join output in series to obtain 10v /15v/25v etc. ?
Do you mean just stack the output DC voltages? Sure.

What is the application? Can you Upload a sketch of what you want to do?
 
  • #3
berkeman said:
What is the application?
get 10 v power supply
 
  • #4
hackhard said:
get 10 v power supply
Why can't you find the right power adapter to get you the right output voltage and power?
 
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  • #5
hackhard said:
multiple 220V to 5v, 2A ac to dc adapters connected to the same 2-phase input terminals
input voltage is 220v domestic supply.
is it safe to i join output in series to obtain 10v /15v/25v etc. ?
hackhard said:
get 10 v power supply
I really can't understand why people want to do things the hard way ??
get a 12V 2A plugpack and use either boost or buck converters to get the required voltages
The converters are dirt cheap on eBay a few $$ each

here's one ideal for your needs, for US$1.52, cheaper than a bunch of plugpacks in series

http://www.ebay.com/itm/DC-DC-Boost...864741?hash=item258c7e1b65:g:K-IAAOSwkl5XdjBMDave
 
  • #6
hackhard said:
multiple 220V to 5v, 2A ac to dc adapters connected to the same 2-phase input terminals
input voltage is 220v domestic supply.
is it safe to i join output in series to obtain 10v /15v/25v etc. ?
Most DC adapters incorporate filtering and deliver relatively smooth DC, but some do not have filtering—their output being rectified AC. It seems that you recognize there may be cases where you need to ensure the supply to all primaries is of identical phase, e.g., in the case of unfiltered output I mention.

It can be safe, but only up to a point. If you keep to under 25V total then it should be okay. There's real danger of exceeding the pack's insulation rating if you try to stack these to get e.g., hundreds of volts out.
 
  • #7
cause I've a bunch of 5v , 2amp adapters lying around
could they be stacked in parallel to get 5v, 4amps out of identical (same product) (5v , 2amp max ) adapters?
and will it be safe if different product , same ratings (5v , 2amp max )plupacks are used in parallel?
 
  • #8
hackhard said:
cause I've a bunch of 5v , 2amp adapters lying around
could they be stacked in parallel to get 5v, 4amps out of identical (same product) (5v , 2amp max ) adapters?
and will it be safe if different product , same ratings (5v , 2amp max )plupacks are used in parallel?
It is certainly not recommended. And I would not power any device of value, not until the arrangement has been well-tested.

I think you should first plot Vo vs. Io over the full load range for the individual adapters. Then only parallel those having almost identical characteristics. You have plenty of the same model, so you should be able to find a couple that are very similar.

Power the parallel pair briefly to start with, then for increasingly longer periods, monitoring the case temperature. If there is any more heat than expected, discontinue the experiment. Test over the full range of loads, before trusting it to power any device that you value.

I'm assuming these are adapters incorporating transformer isolation and that include smoothing so that they output essentially smooth DC.

https://www.physicsforums.com/attachments/110502.gif
 
  • #9
are there any 5v adapters of higher amp rating(higher than 2amp)?
 
  • #10
hackhard said:
are there any 5v adapters of higher amp rating(higher than 2amp)?

How about a google search for "5v 3a adapter"? You could find the answer yourself in mere seconds.

Your question seems to be wandering all over the place. Are you falling into an xy problem? (Google it.) What is it you want to do?
 
  • #11
Integrand said:
How about a google search for "5v 3a adapter"? You could find the answer yourself in mere seconds.

Your question seems to be wandering all over the place. Are you falling into an xy problem? (Google it.) What is it you want to do?
got this http://www.ebay.in/itm/5V-4A-AC-DC-Adapter-Power-Supply-Replacement-Center-/190565150966
 
  • #12
What the others are saying is: instead of proposing solutions, tell us what you need. For example, you could say 'I need to power an XX at 5v 3amps, I have 3 converters'

That is a so-called XY issue - confusing proposed solutions with the real problem.
 
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  • #13
hackhard said:
stacked in parallel
Paralleling voltage sources is generally problematical. If they are simple transformer+rectifier+linear regulator type of power supplies, you may have a better chance of combining them in parallel.

But if they are the smaller, lighter switching power supply type of regulators, then putting their outputs in parallel can cause regulator stability issues. The individual control loops for each switching regulator can cause interference problems with the other regulator, and you can get oscillations and even output over-voltages. That can let the smoke out of the device you are trying to power.

As others are suggesting, just get a power supply of the correct size for your project -- that will work much better, and hopefully let you keep the smoke inside of your device. :smile:
 
  • #14
in series should I have a reverse diode across each supply output to prevent back-driving on overload ?
if the load fails (short circuit or over-current), one of the supplies gives up before the other, then
one supply back-drives the other as with cells in a battery, or cells in a PV-panel.
 
  • #15
hackhard said:
in series should I have a reverse diode across each supply output to prevent back-driving on overload ?
if the load fails (short circuit or over-current), one of the supplies gives up before the other, then
one supply back-drives the other as with cells in a battery, or cells in a PV-panel.
If you are likely to be connecting the arrangement into an even higher voltage source load, then one diode in series with the output should suffice.

In a parallelling configuration a series diode at the output of each would protect against possible damage were a source to not be powered on when the others are, but a diode here is going to lose you some of the +5V and this may be an issue.
 

FAQ: Ac-dc adapters in series (or parallel)

1. What is the purpose of connecting Ac-dc adapters in series or parallel?

The purpose of connecting Ac-dc adapters in series or parallel is to increase the voltage or current output. This is useful when the required output is higher than what a single adapter can provide.

2. What is the difference between connecting Ac-dc adapters in series vs. parallel?

When connecting Ac-dc adapters in series, the positive output of one adapter is connected to the negative input of the next adapter. This results in an increase in voltage but the current remains the same. In contrast, when connecting adapters in parallel, the positive outputs are connected together and the negative inputs are connected together. This results in an increase in current but the voltage remains the same.

3. Can I mix different brands or types of Ac-dc adapters in a series or parallel connection?

No, it is not recommended to mix different brands or types of Ac-dc adapters in a series or parallel connection. This can lead to uneven distribution of voltage or current, which can potentially damage the adapters or the devices they are powering.

4. Is there a limit to the number of Ac-dc adapters that can be connected in series or parallel?

Yes, there is a limit to the number of Ac-dc adapters that can be connected in series or parallel. This limit depends on the specifications of the adapters and should be carefully considered to avoid overloading the adapters.

5. Are there any safety precautions I should take when connecting Ac-dc adapters in series or parallel?

Yes, it is important to follow safety precautions when connecting Ac-dc adapters in series or parallel. This includes using adapters with the same voltage and current ratings, ensuring proper insulation and protection from short circuits, and avoiding overloading the adapters. It is also recommended to consult a professional or refer to the manufacturer's guidelines before attempting to connect adapters in series or parallel.

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