Low Voltage AC Supply from Wall wart?

In summary, the conversation is about using a power brick to create a low voltage ac power supply. The suggested method is to remove the diodes and capacitor and solder the cord to the leads on the transformer. It is suggested to add a fuse, rated slightly below the DC output current of the transformer. The input and output ratings of the power brick are discussed, and it is determined that a fuse should be added to the AC output. The final result is that the suggested method works successfully.
  • #1
5
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Hi - I'm just starting to build a few basic circuits and am looking to get easy access to a low voltage ac power supply. I pulled apart a power brick, and it only has 4 diodes, a cap, and a transformer. If I pull out the cap and the diodes and solder the cord to the leads on the transformer, I should get a pretty safe low voltage ac power source, right? What kind of fuse should I add, if any?
 
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  • #2
Bzap said:
Hi - I'm just starting to build a few basic circuits and am looking to get easy access to a low voltage ac power supply. I pulled apart a power brick, and it only has 4 diodes, a cap, and a transformer. If I pull out the cap and the diodes and solder the cord to the leads on the transformer, I should get a pretty safe low voltage ac power source, right? What kind of fuse should I add, if any?

Yes, that should work fine. You can add a fuse that is rated a bit above what you will be pulling from the transformer. What are the input and output ratings on the unit you have?

BTW, you can get AC wall warts too, not just DC wall warts.
 
  • #3
120 vac, 3.3vac
 
  • #4
Bzap said:
120 vac, 3.3vac

I meant input and output power ratings, not just the voltage ratings. You asked about fusing -- you need to know what kind of power the transformer is designed for, before picking a good fuse value.
 
  • #5
Says it's rated for 350 ma dc.
 
  • #6
Bzap said:
Says it's rated for 350 ma dc.

350mA at 3.3Vdc? That's a pretty small wall wart...?

I'd fuse the AC output a bit below the rated DC output current. That should have reasonable margin.
 
  • #7
It is a pretty small wall wart. It was to a very old USB hub, I think. I'll set this stuff up and let you all know if it works tomorrow.

berkeman said:
350mA at 3.3Vdc? That's a pretty small wall wart...?

I'd fuse the AC output a bit below the rated DC output current. That should have reasonable margin.
 
  • #8
Yep, works! Thanks!
 

What is a "Wall wart" and how does it provide low voltage AC supply?

A "Wall wart" is a nickname for a type of AC adapter that plugs into a wall outlet and converts the high voltage AC electricity from the outlet into a lower voltage that can be used to power electronic devices. It typically consists of a transformer, rectifier, and voltage regulator.

What is considered "low voltage" for AC supply from a wall wart?

The exact range of what is considered "low voltage" can vary, but typically it refers to voltages below 50 volts AC. Some wall warts may provide even lower voltages, such as 5 volts for charging smartphones or 12 volts for powering small electronic devices.

What are the advantages of using a wall wart for low voltage AC supply?

One of the main advantages is convenience - wall warts are compact and easy to use, simply plugging into a wall outlet. They also provide a safe and regulated source of low voltage power, which is important for sensitive electronic devices.

Are there any potential hazards or safety concerns when using a wall wart for low voltage AC supply?

While wall warts are generally safe to use, there are some potential hazards to be aware of. These can include electrical shocks if the wall wart is damaged, overheating if it is overloaded, and potential fire hazards if the wall wart is not used properly or if it is of poor quality.

Can a wall wart be used for other types of power supply, such as DC or high voltage AC?

Some wall warts may have the capability to provide different types of power supply, such as DC or higher voltage AC. However, it is important to check the specifications of the specific wall wart to ensure it can provide the type and voltage of power needed for the intended use.

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