# Simplest way to convert 48 volt dc to 24 VDC

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#### joshua17ss2

##### New Member
I got a bunch of 48 volt power bricks, i was wondering what would be the simplest way to knock the 48 volts down to 24. I thought mabye a single resistor soldered inline but the calculation said it would have to be a 48 watt resistor. I know there must be a simple way to accomplish this.
any help would be greatly appreciated.

#### smanches

##### New Member
Research DC-DC converters. Many, many out there that will do what you want.

#### crutschow

##### Well-Known Member
Unless you can get to the innards of the bricks and find the voltage adjust resistors there's no way to reduce the voltage without dissipating the excess power.

#### Papabravo

##### Well-Known Member
I got a bunch of 48 volt power bricks, i was wondering what would be the simplest way to knock the 48 volts down to 24. I thought mabye a single resistor soldered inline but the calculation said it would have to be a 48 watt resistor. I know there must be a simple way to accomplish this.
any help would be greatly appreciated.
Why is it exactly that you know this? The resistor solution is simple, but wasteful and unreliable. It would not be hard to create conditions that would damage whatever you were trying to power. You need to reset your expectations.

Having done that, go research DC-DC converters as was suggested, and stop messing around. Either that or find loads that operate on 48 Volts so you can use your power bricks or offer to trade them for some 24 volt power bricks.

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##### Banned
You'd have to buy switch mode power supplies for the adapters Joshua. Your resistor calculation was correct if you're drawing about 2 amps from the circuit. If you're drawing 2 amps (what your 48 watt resistor rating suggests) there's no real easy way of dropping the power so switch modes are required, which are significantly more efficient than any form of strictly linear regulation.

#### solis365

##### New Member
however, if you need the 24V dc for low noise applications, a switch mode converter may be a bad idea, as they generate lots of high-frequency noise. so just be careful. however, as suggested, research DC-DC converters. buck, boost, and buck-boost topologies are a good starting point

##### Banned
Boost is useless in his situation (that's an up converter) You can buy SMPS IC's from linear tech rated for a few amps, depends on the exact current requirements joshua's project has. An adjustable SMPS would be quiet handy in his case, there's not that many external components needed and a variable SMPS would allow you to use those 48 volts supplies for almost any project you come up with.

#### Hero999

##### Banned
What are you trying to power?

If it's something resistive such as a light bulb or motor a resistor will do. Another option is to use a square wave oscillator with a duty cycle of 25% which will give the same RMS voltage as 24VDC.

If it's a more complicated load such as a computer, speed controller or PLC then you'll need a proper regulator to do it. If it's a fairly low powered device (i.e <5W) then a linear regulator will do (e.g. LM317), if it's higher powered a switching regulator is the only sensible option.

Lastly, does the output need to be isolated from the input? If so a DC-DC converter is the only option.

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