USB 5V to 1.5V Step Down Converter Circuit

This is a USB 5V to 1.5V Step Down Converter Circuit. It is used instead of a normal AA battery.

In the circuit, we use LM317 DC voltage Regulator. To reduce the 5V input voltage from USB Port to the 1.5V at 1.5A maximum output.

So, this circuit is simple, easy to builds and cheap.

The Working of Circuit

USB 5V to 1.5V Step Down Converter
Figure 1: USB 5V to 1.5V Step Down Converter Circuit


When we use a Cheap MP3 Player (or all Small Appliances). Which use only one 1.5V AA battery as its power supply.

Using the battery is very wasteful.

If we take it to listen to music in the house. Or when the AA battery is suddenly low power. We cannot find another one.

But we have a USB port. It is a popular port anywhere have this.


We can use this circuit to convert 5VDC to 1.5VDC. The power adapter is USB Battery Replacement. To convert USB ports 5V voltage down to 1.5V.

Look at a circuit.

I used a popular IC  – LM317.  They use only 3 parts, include R1 = 470 ohms, R2 = 100 ohms, and LM317-IC1 so very easy.

From the LM317 Regulators CALCULATOR ,

We can calculate output voltage:

Vout = Vref x {1+ (R2/R1)

  •  Vref = 1.25 Volts
  • Typically R1 is 220 ohms or 240 ohms as a datasheet,
    But now this is 470Ω.
  • The R2-resistors is 100Ω

Then we test it in the formula above:
Vout = 1.25 x {1+(100/470)}
= 1.51V (about 1.5 volts)

Or you can change two resistors
R1 = 100Ω
R2 = 20Ω

Related Circuits

DC Regulated to select : 1.5V,3V,4.5V,5V,6V,9V 1.5A
1.2V to 30V Variable DC Power Supply
1.5v to 5v boost converter circuit
1.5V LED flasher circuit

We hope that friends will enjoy listening to music on this circuit. If you made it completely please share it with us.

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I always try to make Electronics Learning Easy.

This Post Has 2 Comments

  1. I got this website from my pal who shared with me on the topic of this
    website and now this time I am browsing this web page and reading very informative
    content here.

  2. Hi there, I tried this step down set up, and I arrived at 1.0 volts. Where was the .5 volt lost?

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