I went over to the car stereo shop right next door to my work to look around, and one of the installers had this small handheld polarity probe. It was plugged into the cigarette lighter and when the tip would touch ground, an LED would shine red, if the same tip would touch 12V+, it would shine green and sound a buzzer. They said they paid $80 for it. 
Talk about high proffit margins. So now I want to build a few. My actual question is, where can I get a similar case? Something like this RS probe would be ideal.
http://www.radioshack.com/product.a...y_name=CTLG_008_002_001_000&product_id=22-807
Thanks.
Talk about high proffit margins. So now I want to build a few. My actual question is, where can I get a similar case? Something like this RS probe would be ideal.http://www.radioshack.com/product.a...y_name=CTLG_008_002_001_000&product_id=22-807
Thanks.