# converting 120v dc to 24v dc

#### tjs4002

Joined Mar 8, 2024
2
Anyone who can give any ideas how to do it?

#### Papabravo

Joined Feb 24, 2006
21,261
Sure, there are a couple of ways, the main ones to consider first are:
1. Buck converter
2. Flyback converter
3. Forward converter
If those don't work, there are some exotic designs you can try.

#### MrChips

Joined Oct 2, 2009
30,946
Anyone who can give any ideas how to do it?
Welcome to AAC!

Specifying 120VDC to 24VDC is only one part of the specifications.
You need to specify the amperage or the power to drawn by the load.

#### tjs4002

Joined Mar 8, 2024
2
Welcome to AAC!

Specifying 120VDC to 24VDC is only one part of the specifications.
You need to specify the amperage or the power to drawn by the load.
upto 5 amps is fine im using this circuit rn to get 120 dc

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#### ronsimpson

Joined Oct 7, 2019
3,144
That circuit will not get you 5A. Probably 5mA.
You need to ask the question: how do I get 120vac to 12V dc at 5A.

Also that circuit does not have isolation. It will get you killed.

#### Lo_volt

Joined Apr 3, 2014
321
Are you trying to experiment or to build something just to learn? Or do you have a project that needs 24 volt DC?

As ronsimpson says, that circuit won't get you 5A. There are plenty of wall-wart style power supplies available. Google 24vdc power supply to find a few.

#### panic mode

Joined Oct 10, 2011
2,808
upto 5 amps is fine im using this circuit rn to get 120 dc
no way...

you are not getting 5A through that 100 ohm resistor.
1Meg resistor is not significant, the Xc is about 1.2k so you get at best 120v/1.2k = 10mA
those 10mA are if output is shorted. if output is open, voltage will rise till 50V filter cap blows up. if it does not blow up it means capacitor has significant leakage current, in which case you still do not get 120VDC.

#### Papabravo

Joined Feb 24, 2006
21,261
upto 5 amps is fine im using this circuit rn to get 120 dc
I'm quite amazed at your ability to be misled by a flashy picture, a complete misunderstanding of the underlying principles, and reckless disregard for your personal safety.

#### MisterBill2

Joined Jan 23, 2018
18,986
If the actual power source is AC, 120 volts, that makes the conversion much simpler. You will need a suitable transformer with the required current rating for the secondary, which in this case should be at least 5 amps. The secondary voltage should be at least 20 volts, 24 is better, and a four-diode bridge rectifier assembly.. OR you can get a transformer with a center tapped 48 volt secondary and you only need two of the expensive diodes.
Either scheme will get you 24 volts DC that will need some filtering. How much filtering will depend on the application of the 24 volt power.
That circuit shown in post #4 will result in a blown up capacitor and a burned out LED almost immediately after it is powered.

#### ronsimpson

Joined Oct 7, 2019
3,144
Go to amazon.com and type in "power supply 12v 5a". You will see many options.

#### MisterBill2

Joined Jan 23, 2018
18,986
Indeed I did get one of those aluminum cased power supplies to replace an external computer supply that was destroyed by lightning.It was about \$21 (USD). I don't recall the vendor. But it was a switcher supply, not sure how it would workto power a music system.