What I search is about a tester (look like pen) which is use to test the circuit is having complete + or - connection or not. This tool is use on car wiring. I know I can just bought the tools. But, I want to try to DIY and having a simple solution for this.
What I thinking is, car have 12V and 24V power. If I want to test the wiring, the tool need to match according to the voltage right. So, is it possible to build the tester that can support 12V and 24V without changing the tool.
It's a very simple device. Nothing but two LEDs with diodes to check for polarity, and a very simple continuity tester based around a battery. Voltage really isn't that important for brief periods of operation.
Thanks for the reply. But, I'm using the tester on 24V and 12V as well. Now, I keep switching the bulb to match the voltage. So, if possible I maintain to use on 12V bulb and some voltage cutoff for the 24V power supply wont hurt my 12V bulb. :) Lazy to keep changing the bulb.. Is it possible?