how to drop voltage from 12v to 2.5v

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=106207
Printed Date: May 11, 2025 at 1:37 AM

Topic: how to drop voltage from 12v to 2.5v

Posted By: megatfauzi76
Subject: how to drop voltage from 12v to 2.5v
Date Posted: July 17, 2008 at 9:34 PM

Hai

I need help. Can anyone guide or give some idea, how to drop 12v from car battery to 2.5v? I need some inffo what kind of resistor and the ohm size of resistor that can drop 12v to 2.5v.

Really need help, coz im goin to do my own bypass kit for my remote start.

Thanks

Replies:

Posted By: dtk1
Date Posted: July 18, 2008 at 12:42 AM

what kind of car ? why not used 1101t DEI

Posted By: megatfauzi76
Date Posted: July 18, 2008 at 1:46 AM

Mine is nissan versa... Can you give some advise what type of resistor i need to use?

Posted By: KPierson
Date Posted: July 18, 2008 at 8:38 AM

Do not use a resistor. Use an adjustable voltage regulator - like a LM317.

You can't get a solid voltage using a resistor only. At bare minimum, you would need two resistors to make a voltage divider. Voltage dividers are great for reference voltages but NOT for powering anything as they lack the ability to provide any type of real current without changing the output voltage.

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Kevin Pierson

Posted By: KPierson
Date Posted: July 18, 2008 at 9:25 AM

https://www.electronics-lab.com/articles/LM317/

Check out that page. It looks like if you use two 240 ohm resistors you will get the 2.5vdc you are looking for.

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Kevin Pierson

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