led test light for 6v and 12v

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URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=136680
Printed Date: May 14, 2025 at 10:35 PM

Topic: led test light for 6v and 12v

Posted By: nissan tech
Subject: led test light for 6v and 12v
Date Posted: May 23, 2014 at 6:28 AM

Hi guys i want to build a led test light that can test not only 12v but 6v also. 12v tester no problem with the 1k ohm resistor but what do I need in the circuit to test 6v also.I would really like 1 tester for both functions but don't know how to switch between the 2 circuits for the 6v circuit cant work on 12v.please help

Replies:

Posted By: oldspark
Date Posted: May 23, 2014 at 11:28 AM

Since you mention a 1k resistor, is it a LED test light?
If so, it might work on 6V.
Otherwise replace the resistor with a constant current source (2 transistors & 1 or 2 resistors) to suit the LED, and handle the ~10V power dissipation.

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